CMC 2003

INGERSOLL-RAND
CENTAC
CMC TECHNICAL REFERENCE MANUAL
(Part No. 22204796)
INGERSOLL-RAND
AIR COMPRESSORS
Copyright Notice
Copyright 1996-2003 Ingersoll-Rand Company
THIS MANUAL IS SOLD "AS IS" AND WITHOUT ANY EXPRESSED OR IMPLIED
WARRANTIES WHATSOEVER.
Printing Date: 24 March 2003
Ingersoll-Rand air compressors are not designed, intended, or approved for breathing air
applications. Ingersoll-Rand does not approve specialized equipment for breathing air
applications and assumes no responsibility or liability for compressors used for breathing air
service.
22204796 Rev. B, Version 3.10

 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Table of Contents
What’s New About the 3.10 Release ______________________________________1
References ___________________________________________________________2
General - CMC Panel ___________________________________________________3
Control Methodology___________________________________________________4
Performance Control _______________________________________________________ 4
PID Control _______________________________________________________________ 7
Surge Control ____________________________________________________________ 12
Prelube Pump ____________________________________________________________ 18
Oil Heater _______________________________________________________________ 18
Protection and Monitoring _____________________________________________19
Analog Functions _________________________________________________________ 19
Digital Functions _________________________________________________________ 19
Compressor Operating Methodology ____________________________________21
Stopped _________________________________________________________________ 21
Rotating_________________________________________________________________ 21
Compressor Operating States ______________________________________________ 23
OUI (Operator User Interface) _______________________________________________ 24
General Sequence of Operation _____________________________________________ 41
Indicator, Switch and Light Layout___________________________________________ 42
CMC Tuning Procedures _______________________________________________42
Setting MaxLoad__________________________________________________________ 42
Setting MinLoad __________________________________________________________ 43
Setting MinLoad Surge Index Increment ______________________________________ 44
Setting Surge Sensitivity ___________________________________________________ 44
Tuning Stability __________________________________________________________ 45
Calibrating the Control Valves ______________________________________________ 46
Autodual Control Settings __________________________________________________ 47
Setting the Start Time _____________________________________________________ 48
Setting the CT Ratio _______________________________________________________ 48
Inlet Unload Position ______________________________________________________ 48
Setting Set Point Ramp Rate ________________________________________________ 48
Alarm and Trip Settings____________________________________________________ 49
22204796 Rev. B, Version 3.10

Troubleshooting _____________________________________________________50
Troubleshooting Example __________________________________________________ 51
Input/Output (I/O) System __________________________________________________ 52
Control Power System (CPS) _______________________________________________ 72
Controller Problems_______________________________________________________ 76
Options _____________________________________________________________78
Enclosures ______________________________________________________________ 78
Control Electrical Package _________________________________________________ 80
Stage Data Package _______________________________________________________ 80
Alarm Horn ______________________________________________________________ 80
Running Unloaded Shutdown Timer _________________________________________ 80
Water Solenoid Post Run Timer _____________________________________________ 80
Panel Mounted Wye-Delta Starter ____________________________________________ 80
N.O. Contact for Remote Indication of Common Alarm and Trip __________________ 80
Power Regulating Constant Voltage Transformer ______________________________ 80
Automatic Starting ________________________________________________________ 81
Remote 4-20 mA Pressure Setpoint __________________________________________ 82
Ambient Control plus Parallel Valve Control Logic _____________________________ 82
Mass Flow Control ________________________________________________________ 84
Steam and Gas Turbine Driven Compressors __________________________________ 85
Diesel Driven Compressors ________________________________________________ 92
Communication ______________________________________________________93
Human Machine Interface (HMI) Systems _____________________________________ 93
Direct CMC Communications with RS422/485__________________________________ 93
The CMC-MODBUS Interface________________________________________________ 94
The CMC-DF1 Interface ___________________________________________________ 115
Documentation______________________________________________________143
System Information __________________________________________________143
Status Codes ___________________________________________________________ 143
Base Control Module (BCM) _______________________________________________ 145
Operator User Interface Module (OUI) _______________________________________ 148
Universal Communication Module (UCM) Optional ____________________________ 152
Technical Specification_______________________________________________160
Glossary _____________________________________________________________1
22204796 Rev. B, Version 3.10
Table of Figures
Figure 1: Compressed Air System ................................................................................................................ 4
Figure 2: Modulate Control .......................................................................................................................... 5
Figure 3: Autodual Control ........................................................................................................................... 5
Figure 4: Performance Control..................................................................................................................... 6
Figure 5: Prpportional Band, Pb................................................................................................................... 7
Figure 6: Proportional Plus Integral Control................................................................................................. 8
Figure 9: MinLoad and MaxLoad ............................................................................................................... 10
Figure 14: Rise to Surge ............................................................................................................................ 14
Figure 15: Changes in Discharge Pressure............................................................................................... 14
Figure 16: Surge Detection System ............................................................................................................ 16
Figure 18: Plant Air System ........................................................................................................................ 42
Figure 19: Troubleshooting Tree................................................................................................................. 50
Figure 21: Measuring Flow ......................................................................................................................... 85
Figure 22: MODBUS Messages................................................................................................................. 95
22204796 Rev. B, Version 3.10

CMC TECHNICAL REFERENCE MANUAL 1
What’s New About the 3.10 Release

This is the initial release of the CMC Manual for version 3.10. This version was created to
support new features incorporated into the CMC Product, and provide additional
information compared with previous versions.
Specifically, new features are as follows:
1. PID Scaling, p.9
2. Valve Characterization, p.15
3. Ambient Control plus Parallel Valve Control Logic, p.82
4. Mass Flow Control, p.84
5. Support for new, high speed IR-Bus at 38.4 kbps
6. Processor upgraded from 16 MHz to 25 MHz on Base Control Module (BCM)
7. Replaceable fuse (F2) for display, p.149
8. Operator instructions on display, p.35
9. “Pop-up” window to provide useful customer information, p.28
22204796 Rev. B, Version 3.10

2 CMC TECHNICAL REFERENCE MANUAL
References
The following references were used in creating this document. All of this documentation is
recommended for a more detailed understanding of specific control modes and control
panel functions.
NEMA STANDARDS PUBLICATION NO. 250, Enclosures for Electrical Equipment (1000 Volts
Maximum), Revision 2, May 1988
NFPA 496 Standard for Purged and Pressurized Enclosures for Electrical Equipment, 1986
Edition
Nisenfeld, A. Eli, Centrifugal Compressors: Principles of Operation and Control, Instrument
Society of America, 1982
Moore, Ralph L., Control of Centrifugal Compressors, Instrument Society of America, 1989
Doebelin, Ernest O., Control System Principles and Design, John Wiley & Sons, 1985
Rowland, James R., Linear Control Systems Modeling, Analysis, and Design, John Wiley &
Sons, 1986
Deshpande, Pradeep B. and Ash, Raymond H., Computer Process Control With Advanced
Control Applications, 2nd Edition, Instrument Society of America, 1988
CENTAC ENERGY MASTER, Version CEM230, Ingersoll-Rand Company, March 1992
White, M.H., Surge Control for Centrifugal Compressors, Chemical Engineering, December 25,
1972
Hall, James W., THERMODYNAMICS OF COMPRESSION: A Review of Fundamentals,
Instrument Society of America, 1976
Gaston, John R., Centrifugal Compressor Operation & Control: Part II "Compressor Operation",
Instrument Society of America, 1976
Gaston, John R., Antisurge Control Schemes For Turbocompressors, Chemical Engineering,
April 1982
Warnock, J. D., Methods for Control of Centrifugal and Reciprocating Compressors, Moore
Products, 1984
Harrison, Howard L. and Bollinger, John G., Introduction to Automatic Controls, Second Edition,
Harper & Row, 1969
22204796 Rev. B, Version 3.10

General - CMC Panel

The CMC panel is the microprocessor-based control and monitoring system for Centac.
The CMC handles compressor control and monitoring functions; as well as, control of
auxiliary equipment such as the main motor starter, oil heater, and prelube pump.
The CMC panel has a custom computer board called the Base Control Module (BCM). This
board has a microcontroller and memory chips that tell the rest of the panel what to do for
the various input pressures, temperatures and vibrations. All hardware for data analysis,
number of input and output (I/O) points and system memory are optimally selected for
accurately controlling and protecting Centac compressors.
Features of the CMC system are:
• Ease of use ... only twelve buttons to push on the operator OUI!
• Multiple function, 240 x 128 pixel graphic LCD to display data, operating status and
basic operator instructions.
• Unload, Modulate and Auto-Dual operating modes.
• Advanced surge detection and control.
• High current limit for main drive electric motor protection.
• First-out indication and event log to help determine the root cause of a compressor trip.
• Pinion vibration alarm and trip for each compression stage.
• Base Control Module CPU running at 25Mhz.
• Base Control Module, Operator User Interface and Universal Communication Modules
capable of serial communication at 38,400 baud
• Optional port for communicating to the Air System Controller (ASC), Air System Manager
(ASM) or other Distributed Control Systems (DCS) via MODBUS protocol.
• Optional reduced voltage motor starter included in panel for some sizes.
NOTE
For the purpose of consistency and clarity, all of the descriptions and examples that
follow refer to "air" for the more generic "gas". Any gas compressed by a Centac
compressor would also apply.
22204796 Rev. B, Version 3.10

Control Methodology
The CMC utilizes performance and surge control methodologies to meet varying
compressed air system needs. The term "performance control" is used for grouping the
control modes that affect compressor power consumption through movement of the intake
and discharge valves.
Performance Control
The CMC has three standard performance control modes or methods of operation. These
modes are Unload, Modulate and Autodual for typical plant air compressors operating in
constant pressure applications. For the discussions that follow, Figure 1 depicts a
compressed air system and the relationship between the compressor and the plant air
system.
Atmosphere
Silencer
Inlet
Valve Bypass
Valve Check
Plant Air System
Valve
Inlet
Compressor
Filter
Figure 1: Compressed Air System
Unload
The compressor is unloaded, when no air is being supplied to the Plant Air System, and all
of the air produced by the compressor is being vented to the atmosphere. In this mode, the
inlet valve is slightly open to allow enough air to pass through the compressor for internal
cooling, prevention of rotor instability and surge avoidance. This air is then discharged
through the open bypass valve to the atmosphere. Typically, the compressor is set to make
a positive pressure across the first compression stage, which produces a discharge
pressure something greater than the atmospheric pressure.
The inlet valve opening required to create this positive pressure is directly related to the
horsepower consumed; therefore, careful consideration should be given to this inlet valve
position for minimizing overall power consumption.
Modulate
Constant pressure control is a frequently required performance control method for Centac
air compressors. If left uncontrolled, the compressor's discharge pressure would rise and
fall along the natural performance curve as system demand changed. Modulate control
satisfies the constant pressure requirement.
The performance map in Figure 2 shows Modulate control. Modulate maintains the system
discharge pressure at the system pressure set point as entered into the CMC by the user.
Once loaded, the compressor will operate along the constant pressure line until the user
switches to Unload or presses the stop button.
22204796 Rev. B, Version 3.10
Control is accomplished by Natural
modulating the inlet valve within Constant Pressure Line

Pressure
Curve
the compressor's throttle range. Surge Line Design

Point
When system demand is less
than the minimum throttled Discharge Maximum
capacity, the discharge pressure Pressure
Throttle Point
(MinLoad)
is maintained by modulating the
bypass valve and venting some Unloaded
or all of the air to atmosphere.

This valve is opened just prior to Inlet
Valve
reaching the surge line. Bypass

Valve
Throttle
Range
Natural
Whenever the bypass valve is Throttle
Range
Power
Curve
open, the inlet valve maintains its
position at the minimum throttled Constant Power Line
Surge Line
capacity setting. Modulate

provides a constant discharge Power at
pressure with variable capacity Coupling
from design to zero.

This control method is used when
Unloaded
stable control of the discharge
pressure is required. Modulate is Capacity
the most commonly used control
method for Centac compressors. Figure 3: Modulate Control
Energy Saving Control - Autodual

Natural
Autodual automatically loads Surge Line Curve
the machine when demand is Unload
Design
Point
high and unloads the machine Point
Reload Point
when demand is low. (Reload Percent)
Discharge
When the compressor is Pressure
controlling to pressure setpoint
and demand is within the inlet
valve throttle range, constant Unloaded
pressure is maintained in the Bypass Inlet
same manner as Modulate. Valve Valve
Throttle Throttle
Range Range Natural
When the machine is controlling Curve
to the pressure setpoint and Unload

Point
system demand is low, the Power at
compressor is operated in the Coupling
bypass valve throttle range.
Autodual automatically unloads
the machine when the bypass
valve is opened beyond the
Unload Point for a programmed Unloaded
time period called the Unload Capacity

Delay Time. The Bypass Valve
Unload Point is selected to Figure 2: Autodual Control
correspond with the check valve
22204796 Rev. B, Version 3.10

closing since at this point the machine is not supplying the system (Figure 3). The Unload
Delay Timer should be set to prevent unloading during short excursions through the Unload
Point. The Reload Percent determines the System Pressure at which the machine will
automatically load into the system.
How does Constant Pressure Modulation Work?

The goal of constant pressure modulation is to maintain a specified discharge pressure in
the compressed air system while the capacity requirements change. Modulate control
provides constant pressure from 100 percent of the compressor's capacity to zero capacity.
Autodual control provides constant pressure from the 100 percent of the compressor's
capacity to the Unload Point.
If all plant air systems were identical in capacity usage requirements, the CMC could be
preprogrammed to respond to those changes; however, all plant air systems are not alike.
The frequency and variability of the capacity changes means that the control logic must be
flexible, so the CMC utilizes proportional, integral and derivative control algorithms to
determine the magnitude of the signal that is sent to the inlet and bypass valves. These
algorithms, or programming logic, allow the CMC control system to be "tuned" to a specific
plant air system.
Measuring the Discharge Pressure
In order to maintain constant pressure, the system discharge air pressure must be
measured. A pressure transducer is mounted in the control panel and tubed to the
compressor discharge downstream of the check valve as shown in Figure 4.
Pneumatic Tubing
CMC PT
4-20 mA
Bypass
Valve PTx
4-20 mA Check
Base
Valve
Control
Module CT Starter
Motor Compressor
Inlet
Valve
4-20 mA
Figure 4: Performance Control

This transducer sends a 4-20 mA signal to the CMC board. The CMC compares the
measured discharge pressure to the system pressure set point entered into the CMC by the
user through the Operator User Interface (OUI). Depending upon the difference between
these two values the CMC will send a 4-20 mA signal to "Modulate", open or close, the inlet
and/or bypass valve to maintain the specified system pressure set point.
22204796 Rev. B, Version 3.10

PID Control
Proportional Band
Proportional control varies the signal sent to the valves as a linear response to the
difference between the actual system pressure and the system pressure set point. Valve
responsiveness can be adjusted through the CMC with the proportional band, Pb, set point.
This set point is the controller gain. Gain is a scaling factor. This scaling factor, graphically
depicted in Figure 5, is the amount of change in the input variable (actual minus set point
pressures) to cause a full scale change in the output variable (valve position).
In other words, if the pressure in the air system fluctuates frequently, it would be prudent to
set Pb to a low value to keep up with those system changes. Otherwise, if the system is
very stable, a larger value can be used. Pb is directly related to valve life and indirectly
related to valve cycling; so, as Pb decreases, valve life decreases and cycling increases.
As stated earlier, the CMC uses a proportional, integral and derivative control algorithm.
The result of proportional only control is offset from the controlled variable, discharge
pressure. This means that if the set point pressure is 100, the actual pressure may only be
95. The value of this offset depends upon the
proportional band value.
What is the valve response when the difference
between actual and set point pressures is zero?
There is no response. Proportional control only
functions when a difference or error exists. Design Output
Variable
discharge pressure could not be attained in a (Valve Position)
proportional only control system. Therefore, an Slow Pb
Response high
integral control algorithm is added to achieve the Full Scale
desired discharge pressure.

Integral Time 0
The offset produced by the proportional control Large Change
algorithm could be eliminated by manually

readjusting the system pressure set point. Using
Fast Pb low
the example above, the set point could be reset to Response
Full Scale
105 to obtain the 100 desired. Manually resetting
the set point would be required as the system Output
demand fluctuated. Integral control, also known as Variable
(Valve Position)
reset control, automatically resets the desired
system pressure set point. For the CMC, the rate
at which the controller resets the system pressure
setting is known as Integral Time, It, and is
expressed in units of repeats per second. 0
Small
If precise control of the specified discharge Change
Input Variable
pressure is required, the It set point should be set (Actual - Set Point Pressures)
for a fast value. It is inversely related to valve life Figure 5: Proportional Band, Pb
and directly related to valve cycling, therefore, as
It decreases, valve life increases and cycling
decreases. For the CMC controlling Centac compressors, It values are typically less than
1.00.
22204796 Rev. B, Version 3.10

Figure 6 shows the

relative valve response Opened
Proportional Band - Low
over time for two Integral Time - Fast
combinations of Pb and It.

As shown, when Pb is low
and It is fast, valve activity Set Point
is significant in both
magnitude and frequency
to obtain the desired set Valve
point. The other scenario, Activity
Pb is high and It is slow,
has relatively little valve
activity, and may never
reach the set point Proportional Band - High
position. Integral Time - Slow
Proportional Band and

Integral Time are Closed
variables used internally Time
by the control system to

determine valve response Figure 6: Proportional Plus Integral Control
and direction for a given
compressed air system. Each has an optimum value based upon the system's
characteristics. Determining these optimum values is a trial and error
exercise. These set points should be re-evaluated any time there is a major change in the
compressed air system.
Derivative Action Derivative Component
Derivative action (also called rate or pre-
Controller
act) anticipates where the process is

Output
heading by looking at the time rate of

change of the controlled variable (its
Proportional Component
derivative). TD is the ‘rate time’ and this
characterizes the derivative action (with
units of seconds).
Error
Derivative action depends on the slope

of the error, unlike P and I. If the error is
constant derivative action has no effect.
The derivative term looks at the rate of
Time
change of the input and adjusts the
output based on the rate of change. Figure 7; PD Controller
Proportional-Integral-Derivative
When an error is introduced to a PID controller, the controller’s response is a combination
of the proportional, integral, and derivative actions, as shown in Figure 8.
Assume the error is due to a slowly increasing process variable. As the error increases, the
proportional action of the PID controller produces an output that is proportional to the error
signal. The reset action of the controller produces an output whose rate of change is
determined by the magnitude of the error. In this case, as the error continues to increase at
a steady rate, the reset output continues to increase its rate of change. The rate action of
22204796 Rev. B, Version 3.10

the controller produces an output whose magnitude is determined by the rate of change.
When combined, these actions produce
an output as shown in Figure 8.
On the combined action curve, the output 10%
is simply the sum of the individual Error 5%
Proportional, Integral and Derivative 0%
corrections.
20%
Note: The response curves in Figure 8 Proportional 10%
Only Action 0%
are drawn assuming no corrective action
is taken by the control system.
Reset
5%
With previous CMC versions, PID settings Only
0%
Action
could vary considerably depending upon
the variable regulated. A PID Scaling Rate 10%
feature has been added to the CMC. This Only 0%
feature will provide for more uniform PID Action
settings for different process control.

55%
Combined
Up to this point, constant pressure control 40%
Output
30%
has been accomplished with an analog
input (system pressure) and two analog
outputs (inlet valve and bypass valve T0 T1 T2
position). In the following paragraphs it
will be discussed how motor current, the
other analog input, is used for constant 1 Sec 2 Sec
pressure control. Also covered in the
following paragraphs is the discussion as
to at what time the bypass valve is
modulated as opposed to inlet valve. Figure 8: Proportional-Integral-Derivative
Motor Current, MinLoad and MaxLoad

Motor current, in units of power (normally amps), has two functions in the CMC. The first is
over current protection for the main motor, and is referred to as MaxLoad or High Load
Limit (HLL). The second function determines the point at which the bypass valve begins to
modulate for controlling pressure. This point is called MinLoad or Throttle Limit (TL). The
location of these two points is graphically depicted on the pressure and power versus
capacity curves as shown in Figure 11.
MaxLoad or High Load Limit (HLL) setpoint, in units of amps, is a parameter entered into
the CMC that prevents the main drive motor from overloading. Once this value is reached,
the CMC logic limits the inlet valve from opening any further. This action constrains the
motor by limiting the amp draw to the maximum allowable service factor amps by using the
inlet valve MaxLoad PID loop to maintain the MaxLoad current setpoint as shown in Figure
9.
When the motor is sized for cold conditions, there are circumstances when MaxLoad will
never be reached. For example, the value of MaxLoad as shown in Figure 9, cannot be
attained for the T=hot curve because it is beyond the maximum compressor capability; that
is, the inlet valve is fully open. This scenario never limits the inlet valve.
22204796 Rev. B, Version 3.10

When ambient conditions produce the

Tcold
T=cold curve, the compressor will
Thot
not be able to achieve the maximum
Discharge Pressure
capacity because it is beyond the
MaxLoad value. Since MaxLoad is
less than or equal to the motor
nameplate FLA times the adjusted
service factor, the maximum
compressor capacity at T=cold could
MaxLoad
MinLoad
only be reached if the motor were sized
for the T=cold condition.
MinLoad Control Setpoint in units of
amps (sometimes referred to as throttle
limit TL) is the power value at which the
Power at Coupling
CMC transfers modulation control from
the inlet to the bypass valve (Figure
10). The reason for this transfer is to
prevent the compressor from entering
into a surge condition. The bypass
valve vents air to the atmosphere and
maintains the pressure setpoint by
using the bypass valve pressure PID
loop. At the same time, the inlet valve
maintains the MinLoad setpoint by Capacity - Mass Flow
using the inlet valve MinLoad PID
loop; therefore, once the MinLoad Figure 9: MinLoad and MaxLoad
setpoint is reached, the compressor

Bypass Valve
Pressure PID continues to produce a constant amount
Control Zone
of air. Part of this air goes to the Plant
Air System, and the remainder is blown
Discharge Inlet Valve off. Even though the Plant Air System
Pressure Pressure PID
Control Zone receives only a portion of the air
HLL
produced, the amount of power remains
TL constant.
The following table presents seven
Inlet Valve
MaxLoad PID
capacity requirements for a plant air
Control Zone system. At each of the capacities, the
table shows the compressor output,
Power at
Inlet Valve
valve position, discharge pressure and
Coupling MinLoad PID power. Each of these values represents
Control Zone
Amps
a percentage and is only an example. P2
is the specified discharge pressure and
P0 is the barometric pressure.
Capacity - Mass Flow
Figure 10: MinLoad
22204796 Rev. B, Version 3.10

System Compressor Compressor Open Position

Required Operating Output Inlet Bypass Discharge
Capacity State Capacity Valve Valve Pressure Power
0 Off 0 0 100 0 0
0 Unloaded 10 10 100 >P0 20
100 Full Load 100 100 0 P2 100
75 MinLoad 75 70 0 P2 80
50 MinLoad 75 70 25 P2 80
25 MinLoad 75 70 50 P2 80
0 MinLoad 75 70 100 P2 80
From the table above, once the system required capacity moves below 75 percent, the
compressor still produces 75 percent capacity with 80 percent of the power. If the system
needs only 25 percent capacity, it will still have to pay for 80 percent of the power. This is
why it is important to open the bypass valve at the last possible moment; therefore, setting
MinLoad properly is critical for efficient energy management.
22204796 Rev. B, Version 3.10

Surge Control
As stated earlier, setting MinLoad properly is critical for efficient energy management.
Also, a well thought-out design method of transferring into and out of the MinLoad state
contributes to good Surge Control. The discussion thus far has only considered motor
current as the point at which the transition from the Loaded state to the MinLoad state
occurs. The following sections will consider methods other than motor current as to when
to transition to the MinLoad state.
‘Surge’ - Definition
Surge is the reversal of flow within one or more stages of a dynamic compressor. This
reversal takes place when the capacity being handled is reduced to a point where
insufficient pressure is being generated to maintain positive capacity. This condition can
potentially damage the compressor if it is severe and is allowed to remain in that state for a
prolonged period; therefore, control and prevention is required.
Control Methodology
Surge prevention is accomplished opening the bypass valve prior to reaching the surge
point. The point at which the bypass valve opens is MinLoad. By blowing a portion of the
air to the atmosphere, the compressed air system gets the air that it demands. The
compressor avoids surge because it is still producing the minimum air capacity.
The following methods of MinLoad control are available on the CMC.
Motor Current
The most common method
determining when to transition to the
Amps vary with voltage
MinLoad status is by using motor
current. Motor current may be
Motor Current, amps
Natural
Surge correlated to flow through the
Points
compressor. As flow increases
through the compressor motor
MinLoad
Setpoint current increases as well. The most
significant factor affecting motor
current is voltage. If voltage
dropped it would cause current to
rise even though no change in flow
Curve "marginally" affected by
occurred. Therefore motor current
changes in inlet temperature at a
can vary as illustrated in Figure 11.
constant inlet pressure
Capacity, scfm
Figure 11: Motor Current Method
22204796 Rev. B, Version 3.10

Optional Motor Power (kW)

Another method of determining when to
transition to MinLoad control on motor
driven units is by using motor power or
Natural
kilowatts (kW). This method takes into
Motor Power, kW
Surge
Points account any changes in motor current due
to the influence of voltage. If voltage drops
MinLoad and current rises, kW would remain
Setpoint constant. This allows for better correlation
in flow through the compressor, therefore,
allowing for more accurate control and
potentially blowing less air to atmosphere.
Curve "marginally" affected by This method virtually eliminated
changes in T1 at a constant P2 inefficiencies due to changes in voltage.
Capacity, scfm
Figure 12: Optional Motor Power, kW
Optional Ambient Control (Polytropic Head)

Another method of determining when to transition to MinLoad control is by using Polytropic
Head calculation. For purposes of the CMC we refer to this method as Ambient Control.
Ambient Control calculates the work
performed by the compressor and is
expressed in foot-pounds per pound
Natural
Surge
of gas (ft-lb/lb). For a given set of
For a given set of
Point hardware (impellers
hardware, the amount of work the
Head, ft-lb/lb
and diffusers) running compressor is capable of is fixed. If

MinLoad at a constant speed, the compressor is called upon to
Setpoint this curve is fixed exceed that amount of work, it will
surge. By knowing the amount of
work the compressor will do before
surging a more conservative
MinLoad point expressed in ft-lb/lb
Curve unaffected by changes in
may be set.
T1, P1 or P2
The ability to set the MinLoad point
closer to the surge line allows the
Capacity, icfm compressor to throttle more (deeper)
Figure 13: Optional Head Control before blowing air to the atmosphere
and thus conserving energy.
Surge Detection
Even though the CMC controls to prevent surge, it can still occur. Insufficient rise to surge,
rapid changes in system discharge pressure, and various other reasons exist for a
compressor to surge.
22204796 Rev. B, Version 3.10

Insufficient Rise To Surge

Rise to surge is the percentage of the compressor's surge pressure to discharge pressure
(see Figure 14). When an insufficient rise to surge situation exists, small fluctuations in the
air system demand and ambient temperature can cause the compressor to surge.
From Figure 14, when T=cold,
there is sufficient rise to surge. As T=cold
the ambient temperature increases
to T=hot, the amount of rise to
Rise
surge decreases because the To T=hot
discharge pressure is remaining Surge
Discharge
constant and the natural curve is Pressure
changing with temperature.
Typically sufficient rise to surge
exists when a ten- percent rise to
surge can be achieved for the
hottest ambient that is expected
Capacity
for the site. If this design criterion
is followed, the control system Figure 14: Rise to Surge
should be able to prevent surge for
variations in air demand and inlet temperature. The same design methodology applies for
changes in cooling water temperature for multi-stage compressors.
Changes in System Discharge Pressure

MinLoad corresponds to a specific constant discharge pressure; therefore, if the discharge
pressure changes, MinLoad must
be reset to properly control surge.
As shown in Figure 15, when the
discharge pressure is changed
from point 1 to 2, a surge can occur
at point 2 if MinLoad is not reset.
TL2
Changes in system discharge Discharge
pressure also apply, but more Pressure TL1
subtly, when the compressor
begins to age. Dirty inlet filter
elements and fouled coolers can
change the compressor's natural
curve; so MinLoad should be
checked periodically to prevent Capacity - Mass Flow
surge from an incorrect setting.
Rapid System Demand Changes Figure 15: Changes in Discharge Pressure

When the system demand varies
rapidly over a wide range of
capacity, the controller may not react fast enough to open the bypass valve to prevent
surge. The CMC reads discharge pressure, motor amps, and approximately twenty other
pressure and temperature inputs; plus controls the inlet and bypass valve position. The
time required to do all of this approximately 100 milliseconds. When the controller is too
slow to react, it is referred to as "driving through MinLoad". The only prevention for a
22204796 Rev. B, Version 3.10

situation like this is to set MinLoad at a more conservative value. The only negative
implication to this is reduced energy savings, because the bypass valve is opened early.
Incorrect Instrumentation Output

If the instrumentation, defined in Figure 4, is improperly calibrated or gives inaccurate
readings, the compressor could surge even though the CMC thinks it should not. Areas of
concern are insufficient power air, incorrect valve transducer calibration, and repeatability of
both inlet and bypass valves. If the valves are being sent signals for specific movements
and they do not respond by moving to the new positions, then the CMC has very little
chance of correctly controlling surge, or even the discharge pressure.
As discussed earlier, the CMC uses motor current as the standard method for determining
when to open the bypass valve. The time to begin opening the bypass valve is near
MinLoad amps. The equation,
I× V× η × PF× 3
GHP= motor
746
indicates that horsepower is directly related to current; it is, but it is also related to voltage.
This is not normally a concern because voltage is primarily constant. However, there are
some locations where extreme voltage variations do exist. In these circumstances, the
CMC cannot correctly determine when it reaches MinLoad and a surge can occur. For
these applications, an optional watt transducer can be used to avoid this situation.
Incorrect Valve Response

Valve Characterization is available on the CMC. Valve characterization allows a more
linear use of the valve throttling characteristics. Linear flow is a flow characteristic in which
the valve relative opening directly correlates to the percentage flow, e.g. a 50 % open valve
gives 50% of maximum flow, with a constant pressure drop across the valve. The CMC
modifies the controller output to allow a more linear response to valve throttling. This
feature requires configuration by an Ingersoll-Rand service technician.
How is Surge Detected?

Note that it has been shown that even though the CMC has surge prevention logic, a surge
can still occur. The CMC has a surge detection system comprised of a surge pressure
transducer and motor current transformer (see Figure 16). The CMC senses surge when
the rate of change in last stage discharge pressure and the rate of change in motor current
are greater than the surge sensitivity setpoint value. When this occurs, the CMC will alarm
and unload the compressor.
22204796 Rev. B, Version 3.10

Pneumatic Tubing
CMC PT
4-20 mA
Bypass
Valve PTx
4-20 mA Check
Base
Valve
Control
Module CT Starter
Motor Compressor
Inlet
Valve
4-20 mA
Figure 16: Surge Detection System
Surge AbsorberTM
When the controller recognizes that a surge occurred, the compressor will unload. With the
Surge AbsorberTM feature enabled, the controller will increment the bypass valve position
by a fixed percentage, send the inlet valve to the MinLoad point (if it is not already there)
and then let normal system demand reload the compressor to the operating pressure. This
process will repeat up to three times within a ten-minute period. If the compressor surges
four times in ten minutes, the compressor will remain unloaded until an operator presses
the reset button. Each detected surge drives a Surge Event to the Event Log. If the
compressor unloads due to repeated surges, a Surge Unload Alarm Event is driven to the
Event Log.
Surge Indexing
MinLoad Since the setting of MinLoad
Surge Control Setpoint is sensitive
Index
Increment to many variables in a
compressed gas system,
Discharge there is potential for the
Pressure setting to require adjustment
throughout the operation of
MinLoad Control Setpoint the compressor. When
MinLoad User Setpoint MinLoad is set incorrectly,
(reset returns control here)
one of two things can
happen. When MinLoad is
set too high, the compressor
Power at will consume excessive
MinLoad Control Setpoint #3
Coupling (currently active) power at MinLoad. When
Amps MinLoad Control Setpoint #1 MinLoad is set too low, the
MinLoad Control Setpoint #1
compressor is allowed to go
past the surge line and
Capacity - Mass Flow surge occurs.
Figure 17: Surge Indexing
22204796 Rev. B, Version 3.10
When Surge Indexing is enabled, it corrects the situation when MinLoad is set too low by
automatically adjusting MinLoad to a higher value upon a surge. The indexed setting,
MinLoad Control Setpoint will remain in effect until MinLoad User Setpoint is Operator User
Interface, or the Reset button is held for more than five seconds. When MinLoad User
Setpoint is manually changed, the MinLoad Control Setpoint is automatically changed to
match the new setting, and when reset, the MinLoad Control Setpoint is reset to the new
MinLoad.
Entering a zero into the MinLoad Surge Index Increment variable disables surge Indexing.
22204796 Rev. B, Version 3.10

Oil System Control

The CMC panel provides control of the prelube pump and lube oil heater in the starting
sequence, during normal operation and after compressor stops or trips.
Prelube Pump
The prelube pump is started when the panel power is on and seal air is present. The
prelube pump stops after the compressor start button is pushed and the programmable
timer “Start Time” has expired. The pump does not come on again until the Stop key is
pressed, and will remain on until the panel power is turned off or Seal Air is lost.
Oil Heater
The oil heater is thermostatically controlled. When the oil temperature is below the set point
temperature, the oil heater is energized, above the set point temperature it is de-energized.
The oil heater control does not have any interaction with the microprocessor board and is
designed to operate with the control panel de-energized as long as three-phase power is
available.
22204796 Rev. B, Version 3.10

Protection and Monitoring

Each CMC base module has twenty-three analog inputs, sixteen digital inputs, four analog
outputs and sixteen digital outputs for control, protection and monitoring. These input
functions provide the CMC with information about the compressor. The CMC board uses
the output functions to communicate to the user and perform actions like starting the
compressor and turning on the prelube pump. All of these inputs and outputs are required
to interface physical actions to and from the electronics.
Analog Functions
An analog function is one in which an electrical signal represents a specific pressure,
temperature, vibration and current input; or valve position output. As these inputs and
outputs fluctuate, the electrical signal to and from the microprocessor board also fluctuates
proportionally to the amount of change.
Analog Inputs
Twenty-one grounded and two floating analog inputs are used for protection, monitoring
and control. Each input used for protecting the compressor can be programmed for alarm
and trip indication. Each of these functions is pre-programmed with the function title,
engineering units, range, alarm and trip values, so no configuration is required upon receipt
by the customer.
The CMC uses pressure transmitters to measure pressure, resistance temperature
detectors (RTD) and transmitters to measure temperature, eddy current based vibration
transmitters to measure shaft vibration and a current transformer to measure the motor
current.
The CMC logic used for the protective alarm and trip functions is as follows: if the actual
value of the input is greater than or equal to the alarm or trip value, indicate the condition.
This logic is used for all inputs except, low oil pressure and low oil temperature where the
logic is reversed. To prevent nuisance alarms and trips, all standard analog inputs use an
alternate alarm and trip value during the stopped, starting, and coasting states. The
alternate setpoints cannot be edited through the Operator User Interface.
Analog Outputs
Two of the available four analog output functions are for inlet and bypass valve positioning.
These are only output functions. The standard configuration for a CMC has no input
information as to the valve location. The CMC calculates the position based upon where the
valves are supposed to be and sends those signals to the valves.
Digital Functions
A digital function is one in which the presence of an electrical signal indicates ON or YES,
and the lack of that signal represents OFF or NO. This is analogous to a light switch that
has only two states, ON or OFF. The term "discrete" is also used instead of digital in many
instances. The term that will be used throughout this documentation shall be digital.
Digital Inputs
The sixteen digital inputs provide status of field switches. Emergency Stop and Low Seal
Air Pressure trip are standard. Any of these inputs can be configured as an alarm or trip. All
inputs operate on 24 VDC power.
22204796 Rev. B, Version 3.10

Digital Outputs
The sixteen digital outputs are used by the CMC to start the prelube pump, energize the
main starter contacts, indicate that an alarm or trip condition exists, indicate that the
compressor is unloaded, activate the running unloaded shutdown timer and to sound the
horn. Outputs can operate on 120 VAC, 60 Hz, single-phase power or 24 VDC power.
22204796 Rev. B, Version 3.10

Compressor Operating Methodology

In the following description of compressor operation, the term “state” is used to indicate
what the compressor is doing, or mode of operation, at any given time. These operating
states exist in a hierarchy. For example, the two highest level states are “Stopped” and
“Rotating”. All other states exist at a level below these two states.
Compressor Operating States

Stopped
This state implies that the compressor is
Motor Driven Packages
NOT rotating. It is important to note that this
+ Compressor is an implication only. If the instrumentation
+ Stopped is not working properly or the system is setup
Waiting improperly, the compressor could be rotating.
Not Ready Waiting
Ready After the panel power is energized, the
+ Rotating controller starts the Waiting Timer and does
Starting not allow further User operation until after the
timer expires. This timer is set at the factory
Unloaded
for two minutes (120 seconds) and is not
A-D Unloaded adjustable. This period allows the
Surge Unload compressor prelube pump to circulate oil
Loading throughout the casing and prevents
restarting while the compressor is coasting
MinLoad
down after an electrical interruption.
Loaded
Full Load Not Ready
MaxLoad When in this state, the compressor is “Not
Ready To Start”. This state is entered when
Unloading
the Waiting Timer has expired and any time
Coasting that a compressor trip has been identified. A
very common and quite often overlooked
reason for the compressor being “Not Ready” is when the Emergency Stop push button has
been engaged. This state can exist indefinitely.
Ready
Similar to the previous state, this state could be redefined as “Ready to Start”. This state is
entered when all compressor permissive functions have been satisfied. This state can exist
indefinitely.
Rotating
This mode does not necessarily mean that the compressor is actually rotating. It means that
it is possibly rotating or rotation is pending and expected.
Starting
Any time after the compressor is ready and a start command is given, this state is entered.
The goal for this period is to get the compressor to rated speed and running unloaded.
“Starting” is allowed for only the Start Timer period and is adjustable. This time period is
limited to a maximum of one minute, or 60 seconds. The reason for the limit is to prevent
22204796 Rev. B, Version 3.10

the compressor from operating in the critical speed for an extended period. Stage vibration
alarm and trip setpoints are increased during this period to get the compressor through the
critical speed region. After the compressor has “Started”, the alarm and trip setpoints are
adjusted back to their original values. The same procedure occurs for stage air temperature
also.
This state exits only after the Starting Timer has expired. THE COMPRESSOR IS ALWAYS
STARTED UNLOADED. On exit of “Starting”, the compressor will return to the mode that it
was in the last time it ran. For example, typical operation implies that prior to stopping the
compressor, the Unload key is pressed. If this occurred, then the compressor will remain in
“Unload” after starting. If the compressor was running and tripped, the compressor will
automatically return to the “Loaded” mode on exit of the Starting state. The User may also
press the Load or Unload key prior to pressing the Start key to force the compressor to into
either post-Starting state.
Unloaded
The compressor is in this state after a start (and Load Selected is not in effect) or when the
User issues an unload command. A-D Unloaded and Surge Unload are also considered
states. However, these two states are really just reasons for being in the Unloaded state. A-
D Unloaded means “AutoDual Unloaded” which occurs when AutoDual is enabled and the
system pressure has been high enough for a long enough time to drive an unload
command. “Surge Unload” is similar in that a surge event drives the unload command
instead of AutoDual. These states can exist indefinitely.
Loading
When a valid load command is issued, the compressor will enter this state. This state exists
until the MinLoad state is satisfied. The duration of this state depends upon PID settings for
the inlet valve at the MinLoad state and the demand for air.
MinLoad, Loaded, Full Load and MaxLoad

These states transition among themselves as demand for air changes. “MinLoad” means
that the bypass valve is controlling pressure and the inlet valve is maintaining the MinLoad
Control Setpoint. “Loaded” means that the inlet valve is controlling pressure and the bypass
valve is closed. “Full Load” occurs when the inlet valve has reached the full open or 100%
position. “MaxLoad” means that the inlet valve is maintaining the MaxLoad Setpoint to
prevent motor damage. In both the “Full Load” and “MaxLoad” states, system pressure may
be lower than setpoint pressure.
Unloading
This state occurs when a valid Unload command is issued and will persist until the
compressor reaches the Unloaded state.
Coasting
When a trip or any stop command is issued and the compressor is running, the motor will
be de-energized and the compressor will begin to coast to a Stopped state. This state will
remain as long as the adjustable Coast Timer is in effect. At the end of the timer, the
compressor will enter either the Ready or Not Ready state.
22204796 Rev. B, Version 3.10

WARNING
Failure to set the Coast Timer for a period greater than or equal to the actual
coasting time can result in compressor damage.

The following diagrams graphically depict the states relative to valve position. This diagram
is provided to assist in the understanding of overall compressor operation.

with Valve Position
Not Ready
Ready
Loading
Starting
Unloaded
Loaded
Full Load
Loaded
Unloading
Unloaded
Coasting
MinLoad
MaxLoad
Waiting
System Pressure Setpoint
Inlet System Pressure Bypass

Valve Valve
milli milli
% %
amps amps
100 20 4 100
75 16 8 75
Stop
Unload or Trip
50 12 12 50
Tight Closure
25 8 16 25
0 4 Load 20 0
Start Inlet Valve Unload Position
Power
On
Stopped Rotating
22204796 Rev. B, Version 3.10

User Interface
OUI (Operator User Interface)

User interface is defined as the means by which people interact with the compressor
control system. The standard configuration of the CMC has two components of the user
interface. They are the OUI and the device plate. The key component of "easy to use" is
that there are only twelve buttons to press on the OUI and four buttons, lights, and switches
on the device plate.
The CMC OUI consists of six command buttons (Start, Stop, Load, Unload, Acknowledge
and Reset), four navigation keys (Up, Right, Left and Down), an Edit mode selection key
(Enter) and a Contrast key. These keys in conjunction with the 240x128-pixel graphics
display make up the user interface to the compressor. The bezel that surrounds the OUI
ensures that the NEMA 4 rating is maintained for the OUI.
CENTAC Microcontroller
SYSTEM INFO SETTINGS
System
Pressure 105.3 Inlet
Valve 95
Pressure
Setpoint 105.0 Bypass
Valve 0
Motor
Current 173.4
Running Hours 11445 22JUL96 12:00:00
Loaded Load Selected

Remote 1/2
22204796 Rev. B, Version 3.10

Command Keys
These keys “command” the compressor to perform actions as specified in the following
table. When any of these keys are pressed the action will be logged in the event log.
Key Name Function

Silences the optional horn or
Acknowledge acknowledges an alarm.
Clears all trip latches. Required to be

Reset pressed after a trip condition to restart
the compressor.
Starts the compressor.
Start
Stops the compressor. This button

Stop should be pressed instead of the E-Stop
for normal operation.
Engages Modulate or Autodual control
Load mode.
Unloads the compressor.

Unload
Enter Key - Display Operating Mode

The Enter key toggles the display between the NAVIGATION mode and the EDIT mode.
Navigation Keys
The arrow keys for Up, Right, Left and Down perform differently depending upon the current
display-operating mode.
FOLDER NAVIGATION
To move among the tabbed folders, press the RIGHT or LEFT key. The folder list is
circular; that is, when the SYSTEM folder is displayed and the LEFT key is pressed, the
SETTINGS folder becomes active. The same is true when the SETTINGS folder is
displayed and the RIGHT key is pressed, the SYSTEM folder becomes active.
PAGE NAVIGATION
To move among each folder’s pages, press the UP and DOWN keys. The page list is also
circular. So, when page 1/4 (pronounced page 1 of 4) is active and the UP key is pressed,
page 4/4 becomes active. Also, when page 4/4 is active and the DOWN key is pressed,
page 1/4 becomes active. The current page for a folder is persistent. For example, if you
begin on the SYSTEM folder page 2, change to the INFO folder and return to the SYSTEM
folder, page 2 will be the page displayed.
22204796 Rev. B, Version 3.10

Contrast Key
This key changes the contrast of the backlight for the graphic LCD display. Pressing this
key steps among each of the thirty two contrast levels. When stepped to the thirty second
level, pressing the key again returns to the first contrast level.
Graphic Display
The 240x128-pixel graphic display allows us to provide a flexible interface between the user
and the compressor. The display has three distinct regions as shown in the diagram below.
Folders
System
Valve 95
Page Pressure
Valve 0
Motor
Current 173.4 22JUL96 12:00:00
Status Bar Load Selected

Loaded Remote 1/2 Page Number
Compressor Compressor Compressor

Operating Control Status
State Location
Graphics Display Area Definitions
Folder and Page

In the design of this system, it is important to provide much of the information required for
operating and troubleshooting the compressor. The tabbed folder with multiple pages
metaphor has been used to reduce the complexity of a traversing at least sixteen pages of
information. For the standard design, the maximum number of keys required to get to any of
the sixteen pages is six. The SYSTEM folder provides information about the compressor
system, the INFO folder gives various types of information about the unit and the
SETTINGS folder is used to perform compressor setup.
Status Bar
The Status Bar provides four distinct types of information (Compressor Operating State,
Compressor Status, Compressor Control Location and Page Number). This region is
always visible from any folder and page combination.
This Field is displayed in large text so that the operator can determine the compressor’s
current operating state at a glance. See Section titled “Compressor Operating Methodology”
for a list of the messages provided.
The Compressor Status Field messages are Trip, E-Stop (emergency stop button
pressed), RMT-Stop (a remote stop has been pressed), Start Disabled (an optional
permissive start condition has not been satisfied), Alarm, Unload Selected (the
compressor will stay in “Unload” after “Starting” has been completed), and Load Selected
(the compressor will go to “Minload” after “Starting” has been completed).
22204796 Rev. B, Version 3.10

The Compressor Control Location Field messages are Local, Remote (remote hardwired
commands i.e. start, stop, load, unload etc.), Network (MODBUS, DF1 or ASC
communication with a UCM) and Remote/Net (both Remote and Network). This indication
is provided to indicate to the operator that a remote location is in control of the compressor
and the compressor may start, stop, load, unload, etc. without the local operator initiating
any commands.
These three fields combine to provide the operator with the necessary information to create
a cursory determination of the status of the compressor. When a more thorough
determination is required, the operator can get additional detail by looking through the other
pages in the system.
The Page Number indicates the current page for the current folder with the number of
pages in the folder. The number of pages is given so that the user always knows where he
is in the system.
Navigation Mode
Navigation mode is active when a folder name (SYSTEM, INFO or SETTINGS) is
highlighted.
Edit (Setpoint Changes) Mode

Edit mode is activated by pressing the ENTER key. In Edit mode one can change
Setpoints for a page. Once in this mode, the highlight will move from around the folder
name to the item to be changed. Use the Right and Left arrow keys to move among the
changeable items and the Up and Down arrow keys to change the value of the item. When
changes are complete, press the Enter key again to return to Navigation mode.
Scroll Mode
Scroll mode is activated by pressing the ENTER key when a folder name INFO is
highlighted and the Event Log or the Routine Start / Stop page is visible. The Scroll mode
is used to page through the event log. To move among the pages, press the UP or DOWN
keys. To deactivate the Scroll mode, press the Enter key.
22204796 Rev. B, Version 3.10

Pop-up Message
In the event of an Alarm or Trip, a pop-up message will appear providing the customer with
the phone number of the local Ingersoll-Rand representative. If the event is a Trip, the
event log on the SYSTEM folder will be displayed with the pop-up message centered over
the displayed page. The message may be removed by pressing the ENTER key. The
following are examples of the pop-up message in the event of an Alarm or Trip.
Alarm Example Trip Example

SYSTEM INFO SETTINGS INFO SETTINGS
SYSTEM
System
For Parts orValve
Service 100 1
Event Name
Low Oil Pressure
For PartsTrip
Time Date
09:18:44 0720
or Service
Please Call:Bypass
Setpoint 105.0
Pressure
Valve
39 02 950 56499
0 2
3
Low Oil Pressure Alarm
Please Call:
Reset key pressed
39 02 950Trip
09:18:43 0720
09:18:34 0720
56499 09:08:43 0720
4 Low Oil Pressure
Motor
Current 323.4
Press ENTER key to continue
5
6
LoadPress
key pressed
08:58:23 0720
08:24:01 0720
ENTER key to continue
Running Hrs: 11445 31-AUG-1999 12:00:00 7 Start key pressed 08:23:12 0720
Trip
Remote 1/4 Not Ready Remote 2/3
22204796 Rev. B, Version 3.10

SYSTEM Folder INFO Folder SETTINGS Folder
SYSTEM INFO SETTINGS SYSTEM INFO SETTINGS SYSTEM INFO SETTINGS
System
Valve 100 HORN SILENCE
CONTRAST
UP
Password
Setpoint Changes Enabled
* * * *
Language and Units

Pressure
Valve 0 RESET
LEFT RIGHT
DOWN
English degF mils amps psi
English degC mils amps kg/cm2
Motor
Current 323.4 START LOAD UNLOAD ENTER
Date, yyyy/mm/dd 1999/08/31
STOP
Running Hrs: 11445 31-AUG-1999 12:00:00 Time, hh:mm:ss 12:30:00

Remote 1/4 Loaded Load Selected
Remote 1/6

Pressure Temperature Vibration Event Name Time Date
MaxLoad (HLL) 400.0
Stage 1 30.1 95.8 0.25 1 Low Oil Pressure Trip 09:18:44 0720 MinLoad
Stage 2 106.6 93.5 0.22 2 Low Oil Pressure Alarm 09:18:43 0720 User Setpoint (TL) 100.0
Oil 18.8 115.3 3 Reset key pressed 09:18:34 0720 Control Setpoint 100.0
Water 80.1 4 Low Oil Pressure Trip 09:08:43 0720 Surge Index Increment 1.0
5 Low Oil Pressure Alarm 08:58:23 0720
6 Load key pressed 08:24:01 0720 Surge Absorber Enabled
7 Start key pressed 08:23:12 0720 Surge Sensitivity 9.0

Remote 2/4 Not Ready Trip
Remote 2/6
Digital Inputs Power On Hours 12338 PB IT D

Starter Feedback Running Hours 11445 rep/sec sec
E-Stop Pressed Loaded Hours 11223 Inlet Valve
Low Seal Air Number of Starts 35 Pressure 10.00 0.50 0.00
MinLoad (TL) 25.00 0.50 0.00
MaxLoad (HLL) 99.99 0.50 0.00
BCM Ver: 2.51 Bypass Valve
Pressure 10.00 0.50 0.00
Load Selected Load Selected
Loaded Remote 3/4 Loaded Remote 3/6 Loaded Load Selected
Remote 3/6
Digital Outputs Control Mode

Prelube Pump Running For parts or service contact your Manual
CR1 local Ingersoll-Rand representative Modulate
Remote Trouble at the following number: Autodual
Reload Pressure, % of Setpoint 98
39 02 950 56499
Unload Point, BV % Open 1
Unload Delay Time, seconds 1

Remote 4/4 Ready Load Selected
Remote 4/6
SYSTEM INFO SETTINGS SYSTEM INFO SETTINGS
Navigation and R E P
Part No.
L A C E M E N T P A R T S
Description
Starting Timer, seconds
Coasting Timer, seconds
20
240
Enter Keys 12345678
12345678
Inlet Filter Element Primary
Inlet Filter Element Secondary
CT Ratio
Inlet Unload Position, %
60
15
12345678 Oil Filter Setpoint Ramp Rate, pressure/scan 5.0
12345678 Demister Element
12345678 Lubricant, 55 gallon drum
Load Selected
Ready Load Selected
Remote 5/6 Loaded Remote 5/6
SYSTEM INFO SETTINGS SYSTEM INFO SETTINGS

R O U T I N E S T A R T / S T O P Alarm Trip
Prior to starting, the operator should Stage 1 Temperature 120 125
become familiar with the operation of Stage 1 Vibration 0.80 1.00
the main driver. Refer to the driver Stage 2 Temperature 120 125
manufacturer's instructions in the Stage 2 Vibration 0.75 0.95
Operation Manual. The operator should Oil Pressure 18 16
also be familiar with all the accessory High Oil Temperature 120 125
and optional equipment contained on the Low Oil Temperature 100 95
Load Selected
Ready Remote 6/6 Loaded Load Selected
Remote 6/6
22204796 Rev. B, Version 3.10

SYSTEM Folder
The SYSTEM folder provides information about the compressor system. The number of
pages in this folder is at least four; but could be more for two stage machines with special
analog options purchased, or for
SYSTEM INFO SETTINGS compressors with three stages or
more.
System
Valve 100 This page shows the main
compressor operating parameters,
Pressure
Valve 0 running hours, date and time. The
System Pressure and Pressure
Motor
Current 323.4 Setpoint are in units as defined by
Running Hours: 11445 31-AUG-1999 12:00:00 the Settings page, Motor Current is
in Amps and valve positions are in
Remote 1/4
percent open. Pressure Setpoint is
System Folder – Page 1: System Pressure always editable while the Inlet and
Bypass Valve positions are edit
enabled when in the Manual mode
only. These are the only editable settings in any folder other than the Settings Folder.
Info Folder Page 1 Edit Parameters Table

Minimum Maximum Step
Variable Units Value Value Size
Pressure Setpoint pressure 0.0 999.9 0.1
Inlet Valve Position (manual mode only) percent 0 100 1
Bypass Valve Position (manual mode only) percent 0 100 1
The Analog Input page provides the SYSTEM INFO SETTINGS

actual value for each stage pressure,
Press Temp Vib
temperature and vibration, oil pressure Stage 1 30.1 95.8 0.25
and temperature. If additional analog Stage 2 106.6 93.5 0.22
inputs have been purchased or more Oil 20.3 105.5
stages exist as standard, it is likely that an
additional page or pages will be added.
The units are as defined by the Settings
page. There are no editable setpoints on
this page. Loaded Load Selected
Remote 2/4
The Digital Input page shows the current

state of the digital (discrete) inputs for the SYSTEM INFO SETTINGS
system. The number of inputs will vary Digital Inputs
depending upon the number of optional Starter Feedback
inputs purchased. A check in the box to E-Stop Pressed
Low Seal Air
the left of the text indicates a TRUE
condition, whereas, no check indicates a
FALSE condition. For example, a check
mark in the “E-Stop Pressed” boxed
means that the Emergency Stop push Load Selected
button has been pressed. It is possible to Loaded Remote 3/4
have multiple Digital Input pages.
System Folder - Pages 2,3: Analog/Digital Inputs
22204796 Rev. B, Version 3.10

The Digital Output page is similar

SYSTEM INFO SETTINGS to the Digital Input page except
Digital Outputs
that it shows the current state of
Prelube Pump Running the digital (discrete) outputs for the
CR1 system. The number of outputs will
Remote Trouble vary depending upon the number
of optional items purchased. A
check in the box to the left of the
text indicates a TRUE condition,
Load Selected whereas, no check indicates a
Loaded Remote 4/4 FALSE condition. It is possible to
have multiple Digital Output pages.
System Folder - Page 4: Digital Outputs
The SYSTEM folder’s four pages
give the current operating status for the compressor. The User is always within two
keystrokes of all operating parameters.
INFO Folder
The INFO folder contains the OUI key map, the compressor event log, the hour meters, the
phone number to call for parts or service, a list of part numbers for consumable parts and
routine start/stop and
maintenance instructions. There SYSTEM INFO SETTINGS
are no editable setpoints in this
Event Name Time Date
folder. The OUI key map will be 1 Low Oil Pressure Trip 09:18:44 0720
the default page on power up. 2 Low Oil Pressure Alarm 09:18:43 0720
The keys are labeled in English 3 Reset key pressed 09:18:34 0720
and the local language, 4 Low Oil Pressure Trip 09:08:43 0720
depending upon the current
6 Load key pressed 08:24:01 0720
language selected. 7 Start key pressed 08:23:12 0720
The Event Log details the last Trip
two-hundred twenty four (224) Not Ready Remote 2/6
“events” that have occurred.

Each “event” has a date and time Info Folder - Page 2: Scrollable Event Log
stamp. This log will list all Alarms
and Trips and provides first-out indication. Any time an Alarm or Trip is indicated on the
Status Bar, the detail for that fault is included here.
The event labeled as “1” is the newest event and “7” is the oldest event. For events that
have identical Time and Date values, the order is still correct (newest to oldest, top to
bottom). Once the list is full, each new event knocks off the last event.
Pressing the Enter key to initiate Scroll Mode allows access to events 17 through 224.
Scroll Mode is indicated by the reverse video of the event numbers. Each Down Arrow
press displays the next seven events. An Up Arrow press will display the previous seven
events. Any time a Trip occurs, the system will send the display to the first seven events.
22204796 Rev. B, Version 3.10

Possible Events List
Event Name Description

* * End of List * * Displayed for the event name whenever the event list is not full.
A/I Alarm The actual value for Analog Input “AI” is greater than the Alarm value.
A/I Trip The actual value for Analog Input “AI” is greater than the Trip value.
Acknowledge (Location) An Acknowledge command has been issued from Location.
Auto Dual Mode Enabled The Auto Dual Mode has been enabled
Auto Start An automatic start occurred (typically from Auto Hot or Cold Start).
Auto Stop An automatic stop occurred (typically from Running Unloaded Shutdown Timer).
BCM 2 Failure Alarm Communications have been lost to Base Control Module #2.
BCM 3 Failure Alarm Communications have been lost to Base Control Module #3.
Compressor Started The compressor has started.
DI Alarm The Discrete Input “DI” is in an alarm condition.
Discrete Surge A discrete surge switch has detected a surge.
DI Trip The Discrete Input “DI” is in a trip condition.
Driver Trip Drive controller feedback was not received after a start command was issued
Edit-x AI Alarm SP The Analog Input “AI” Alarm setpoint value has been edited from location x.
Edit-x AI Trip SP The Analog Input “AI” Trip setpoint value has been edited from location x.
Edit-x A/D Reload Pct The AutoDual Reload Percent value has been edited from location x.
Edit-x A/D Unload Dly The value has been edited from location x.
Edit-x A/D Unload Pt The AutoDual Unload Point value has been edited from location x.
Edit-x AHS Pressure The Auto Hot Start Pressure value has been edited from location x.
Edit-x Auto Stop Time The Auto Stop Timer value has been edited from location x.
Edit-x BV Position The Bypass Valve Position value has been edited while in Manual from location x.
Edit-x BV-PID D The Bypass Valve Pressure PID Derivative value has been edited from location x.
Edit-x BV-PID It The Bypass Valve Pressure PID Integral Time value has been edited from location x.
Edit-x BV-PID Pb The Bypass Valve Pressure PID Proportional Band value has been edited from location x.
Edit-x Coasting Timer The Coasting Timer value has been edited from location x.
Edit-x CT Ratio The CT Ratio value has been edited from location x.
Edit-x Day The Day value for the Date field has been edited from location x.
Edit-x IV Position The Inlet Valve Position value when in Manual has been edited from location x.
Edit-x IV Unload Pos The Inlet Valve Unload Position value has been edited from location x.
Edit-x IV-PID D The Inlet Valve Pressure PID Derivative value has been edited from location x.
Edit-x IV-PID It The Inlet Valve Pressure PID Integral Time value has been edited from location x.
Edit-x IV-PID Pb The Inlet Valve Pressure PID Proportional Band value has been edited from location x.
Edit-x MaxLoad SP The MaxLoad Setpoint value has been edited from location x.
Edit-x MaxLoad-PID D The Inlet Valve MaxLoad PID Derivative value has been edited from location x.
Edit-x MaxLoad-PID It The Inlet Valve MaxLoad PID Integral Time value has been edited from location x.
Edit-x MaxLoad-PID Pb The Inlet Valve MaxLoad PID Proportional Band value has been edited from location x.
Edit-x MinLoad Index The MinLoad Surge Index Increment value has been edited from location x.
Edit-x MinLoad SP The MinLoad Setpoint value has been edited from location x.
Edit-x MinLoad-PID D The Bypass Valve Pressure PID Derivative value has been edited from location x.
Edit-x MinLoad-PID It The Bypass Valve Pressure PID Integral Time value has been edited from location x.
Edit-x MinLoad-PID Pb The Bypass Valve Pressure PID Proportional Band value has been edited from location x.
Edit-x Month The Month value for the Date field has been edited from location x.
Edit-x PSP Ramp Rate The Pressure Setpoint Ramp Rate value has been edited from location x.
Edit-x Process SP The Process Set Point value has been edited from location x.
Edit-x Sensitivity The Surge Sensitivity value has been edited from location x.
22204796 Rev. B, Version 3.10

Edit-x Starting Timer The Starting Timer value has been edited from location x.
Edit-x Sys Press SP The System Pressure Setpoint value has been edited from location x.
Edit-x Time The Time value has been edited from location x.
Edit-x Waiting Timer The Wait Timer has be edited from location x.
Edit-x Year The Year value for the Date field has been edited from location x.
E-Stop pressed Emergency Stop push button has been pressed.
Fail to Roll Did not achieve minimum slow roll speed in allotted time
Illegal Rotation Unexpected rotation from driver
Load (Location) A Load command has been issued from network communications.
Loss of Motor Current Motor current feedback was lost while running.
MinLoad Clamped The MinLoad Control or User Setpoint value has been limited to the MaxLoad Setpoint value.
MinLoad Incremented The MinLoad Control Setpoint value has been incremented as a result of surge.
MinLoad Reset The MinLoad Control Setpoint value has been reset to the MinLoad User Setpoint value.
Modulate Mode Enabled The Modulate Mode has been enabled.
Power Down The Base Control Module (BCM) was de-energized.
Power Up The Base Control Module (BCM) was energized.
Reset (Location) A Reset command has been issued from Location.
Start (Location) A Start command has been issued from Location.
Starter Failure Starter feedback was not received after a Start command was issued.
Starter Fault-Closed Motor stopped but feedback present for 2 seconds
Starting Fail Driver feedback was not received after a Start command was issued.
Stop (Location) A Stop command has been issued from Location.
Surge The controller has detected a Surge.
Surge Unload Alarm The alarm condition when the compressor has unloaded as a result of multiple surges.
TTV Switch Fault Trip Limit Switch Stuck
Unload (Location) An Unload command has been issued from Location.
NOTE 1: “Location” is replaced by “Comm” for communications network, “Local” for local compressor display and “Remote” for
hardwired remote communications.
NOTE 2: “x” is replaced by “C” for edits from a communication network and “L” for edits from the local display.
NOTE 3: All Analog Inputs that have alarm and trip sepoints get edit local, edit communications, alarm and trip event
messages.
NOTE 4: All Discrete Inputs for Alarm or Trip get alarm and trip event messages.
This next page of the INFO Folder shows the hour meters and number of starts. Power On
Hours is the time that the panel
power has been on. The Running SYSTEM INFO SETTINGS
Hours are the amount of time that Power On Hours 12338
the compressor has been Running Hours 11445
operating between all start and Loaded Hours 11223
stop sequence. The Loaded Number of Starts 35
Hours is the amount of time that
the compressor has been running BCM Ver: 3.00
and not running unloaded. It can
also be defined as the number of Load Selected
hours that the inlet valve is not in Loaded Remote 3/6
the Inlet Unload Position. The Info Folder – Page 3: Hour Meters and Version
Number of (Compressor) Starts is
self-explanatory.
22204796 Rev. B, Version 3.10

NOTE
Most electric motors are only rated for two cold starts or one hot start per hour. It is
the operator’s responsibility not to exceed the electric motor’s limitation. The control
system allows the compressor to be started when the compressor is ready, not the
motor.
The last item on this page is the Base Control Module Version number. This will be used by
field personnel for quick reference to determine if newer software is available.

This page of the INFO folder
shows the phone number to call for
parts or service. This is the For parts or service contact your
number of the local Ingersoll-Rand local Ingersoll-Rand representative
representative. The number can be at the following number:
changed only by use of Service 39 02 950 56499
Tool.
Trip
Ready Remote 4/6
Info Folder – Page 4: Phone Number
This page provides a list of

consumable parts found on the SYSTEM INFO SETTINGS
compressor package. These parts R E P L A C E M E N T P A R T S
may also be located in the Part No. Description
compressor bill of materials. In the 12345678 Inlet Filter Element Primary
12345678 Inlet Filter Element Secondary
event of a discrepancy, the 12345678 Oil Filter
compressor’s bill of materials always 12345678 Demister Element
takes precedence over this page. In 12345678 Lubricant, 5 gallons
the event that the part numbers are
not available, such as retrofitting the Trip
CMC on a competitive machine, this Ready Remote 5/6
screen may not be visible. Info Folder – Page 5: Replacement Parts
22204796 Rev. B, Version 3.10

Basic operator instructions are provided on the Routine Start/Stop and Maintenance pages.
Pressing the Enter key to initiate Scroll Mode allows access to the entire instructions.
Scroll Mode is indicated by the reverse
video of a slide bar. Each Down Arrow SYSTEM INFO SETTINGS
press displays the next eight lines of R O U T I N E S T A R T / S T O P
instructions. An Up Arrow press will Prior to starting, the operator should
display the previous eight lines of become familiar with the operation of
instructions. The slide bar on the page the main driver. Refer to the driver
indicates current location within the text. manufacturer's instructions in the
Operation Manual. The operator should
If a Trip occurs while on this page, the also be familiar with all the accessory
system will send the display to the event and optional equipment contained on the
log page. Trip
Ready Remote 6/6
Info Folder – Page 6: Operator Instructions

SETTINGS Folder
The SETTINGS folder is used for compressor setup. In this folder, the User will enter
performance and control operating parameters, analog health monitoring settings for Alarm
and Trip conditions, control mode selection, setpoint changes, password, and user interface
language. This folder is the primary location for editing setpoints.
The Password is used for determining
whether Setpoint Changes can be SYSTEM INFO SETTINGS
made. The Password takes four Password * * * *
numbers. If the Password is entered Setpoint Changes Enabled
properly, Changes will be enabled (a Language and Units
check will be in the box); otherwise, English degF mils amps psi
English degC mils amps kg/cm2
they are disabled. This enabling and
disabling applies to all changeable Date, yyyy/mm/dd 1999/08/31
setpoints except, Pressure Setpoint, Time, hh:mm:ss 12:30:00
Throttle Limit, language selection and Load Selected
the Password, these items are always Loaded Remote 1/6
modifiable.
Settings Folder - Page 1: Password, Language,
Each control system is shipped with Time and Date
two languages and units of measure
combinations. The first set is for the English language, pressures in units of PSIG,
temperatures in units of degrees F and vibrations in units of mils. The other set will be
localized for the customer. The default alternate language is English with Metric units.
Language support will be provided for those listed in the Technical Specification located at
the end of the manual. Others will be available as required and translations can be
obtained. This system has the ability for any language because of the graphics display.
Asian character support will require additional screens because these characters require
four times the number of pixels. There are no limitations on the units of measure. Each
analog input has its own scaling factor and offset.
The Date is set with three separate values (1) Year, including century (2) Month and (3)
Day. The Time is also set with three values (1) Hour, (2) Minutes and (3) Seconds.
22204796 Rev. B, Version 3.10

Settings Folder Page 1 Edit Parameters Table

Password Digit dimensionless 0 9 1
Date (Year) years 1990 2089 1
Date (Month) months 1 12 1
Date (Day) days 1 31 1
Time (Hour) hours 0 23 1
Time (Minute) minutes 0 59 1
Time (Second) seconds 0 59 1
The Anti-surge Settings and Driver Over-Load Protection Page has all of the settings for
controlling and detecting surge conditions and protecting the main driver from over load
conditions.
The MaxLoad (HLL) setpoint
SYSTEM INFO SETTINGS prevents the compressor driver
from overloading. MinLoad User
MaxLoad (HLL), amps 400.0
MinLoad
Setpoint (TL) is the value used to
User Setpoint (TL), amps 100.0 determine what the initial (before
Control Setpoint, amps 100.0 indexing) motor current value will
Surge Index Increment, amps 1.0 be when constant pressure control
Surge Absorber Enabled operation switches from the inlet
Surge Sensitivity 9.0 valve to the bypass valve.
Load Selected MinLoad Control Setpoint is the
Loaded Remote 2/6 actual value used to determine
when the bypass valve begins
Settings Folder - Page 2: Anti-Surge and Driver constant pressure control in lieu of
Over-Load Protection
the inlet valve. This value equals
the MinLoad User Setpoint plus the
number of surges times the index increment value. MinLoad Surge Index Increment is the
value that the Control Setpoint is indexed after a surge has been detected. If the value for
Surge Index Increment is equal to zero, Surge Indexing is disabled.
To reset the MinLoad Control Setpoint to the MinLoad User Setpoint, hold the reset key for
at least five seconds. The indication that it has been reset will be in the event log. The
event message “MinLoad Reset” will be displayed. Another indication is when the MinLoad
User Setpoint value equals the MinLoad Control Setpoint value.
The Surge Absorber Enabled checkbox allows the user to turn off or on the Surge Absorber
feature. When disabled, the compressor will Unload on any surge condition.
The Surge Sensitivity setting has a range from zero (0.0) to ten point nine (10.9) where one
is not sensitive (a “soft” surge condition could exist without being identified) and ten is very
sensitive (a “soft” surge condition would be identified). We ship the machine with a default
value of nine (9). This setting will pick up most surge conditions.
22204796 Rev. B, Version 3.10


MaxLoad (HLL) amps 0.0 9999.9 0.1
MinLoad User Setpoint (TL) amps 0.0 100.0 0.1
MinLoad Surge Index Increment amps 0.0 9999.9 0.1
Surge Sensitivity dimensionless 0.0 10.9 0.1
NOTE
MinLoad Control Setpoint is the motor amperage value used to determine when the
bypass valve opens. MinLoad Control Setpoint will always be equal to or greater than
the Throttle Limit value.
CAUTION
The MaxLoad (HLL) value should not exceed the value determined in the
section titled Setting MaxLoad. Failure to set this properly could result in damage to
the motor.
CAUTION
When Surge Indexing is enabled and the compressor surges several times,
the compressor will begin bypassing air sooner than when Surge Indexing is
disabled. You should periodically reset the MinLoad Control Setpoint to prevent
excessive air bypass.
CAUTION
Repeated surging can cause damage to the compressor; therefore, use

caution when desensitizing the Surge Sensitivity setting.
22204796 Rev. B, Version 3.10

The Control Parameters Page is

used for matching the control SETTINGS
SYSTEM INFO
system to the local application.
The Proportional Band (PB), PB IT D
rep/sec sec
Integral Time (IT) and Derivative Inlet Valve
(D) settings are provided for Pressure 10.0 0.50 0.00
both the inlet valve and bypass MinLoad (TL) 25.00 0.50 0.00
valves. This gives the controller MaxLoad (HLL) 99.99 0.50 0.00
Bypass Valve
precise control for modeling the
Pressure 10.0 0.50 0.00
air system over the entire
Load Selected
operating range of the
compressor. With this release,
Loaded Remote 3/6
the Derivative constant has Settings Folder - Page 3: Control Parameters

been added to give even more (PID Settings)
capability to match the control
system to the air system. However, we recommend that this value remain at zero unless
you have full understanding of how this parameter works.

Each PB (Proportional Band) dimensionless 0.0 99.99 0.1
Each It (Integral Band) repeats/second 0.0 99.99 0.1
Each D (Derivative Band) seconds 0.0 99.99 0.1
CAUTION
Setting the Derivative parameter to a value other than zero for any of the PID
settings may cause the valve output to change rapidly. Please change this value with
caution.
The Control Mode Selection Page

allows the User to select between
the two standard control modes, Control Mode
Modulate and Autodual. This Manual
selection process is performed Modulate
Autodual
with the radio button selector. To Reload Pressure, % of Setpoint 98
change the selection, press the Unload Point, BV % Open 1
Up or Down arrow key. Unload Delay Timer, seconds 1
Reload Percent, Unload Point Load Selected

and Unload Delay Time are all Loaded Remote 4/6
setpoints for Autodual control.
Settings Folder - Page 4: Control Mode Selection
Checking the Manual checkbox enables manual valve control. In this mode, the inlet valve
may be stroked when the compressor is not running, and the bypass valve can be stroked
22204796 Rev. B, Version 3.10
at any time. If a surge condition occurs while manually controlling these valves, the CMC
will automatically take over the valves.

Autodual Reload Pressure % of Setpoint 0 99 1
Autodual Unload Point BV % Open 1 99 1
Autodual Unload Delay Timer seconds 0 999 1
CAUTION
Manual should only be used for compressor setup.
Starting Timer is the length of time prior to enabling the loading of the compressor.
Typically, this time includes the starter transition time (Y-D time) and the prelube pump
shutdown. When this timer expires, the prelube pump will turn off and the compressor is
enabled for loading.
Coasting Timer is the length of time that it takes for the driver to stop rotating.
CT Ratio is the ratio of the current
SYSTEM INFO SETTINGS transformer primary to the
secondary; i.e., if the CT primary
Starting Timer, seconds 20 winding is 300 and the secondary
Coasting Timer, seconds 240
CT Ratio 60
winding is 5, then the CT Ratio is
Motor Failure Trip Enable 60.
Inlet Valve Unload Position, % 15
Setpoint Ramp Rate, pressure/scan 5.0 When checked, Motor Failure Trip
Enable tests that the zero_amp
motor_current variable has been
Load Selected reached after a start command has
Loaded Remote 5/6
been initiated and that motor
Settings Folder - Page 5: Miscellaneous current is not lost while the
compressor is running. Uncheck
this box for dry run conditions.
The Inlet Unload Position is the position of the inlet valve when in the unload state.
Setpoint Ramp Rate is used to prevent system pressure overshoot during compressor
loading.
Additional settings will be added to this page for “special” features.
22204796 Rev. B, Version 3.10


Starting Timer seconds 5 60 1
Coasting Timer seconds 60 9999 1
CT Ratio dimensionless 60 9999 1
Inlet Valve Unload Position percent 0 100 1
Setpoint Ramp Rate pressure/scan 0 999.9 0.1
WARNING
Failure to set the Coast Timer for a period greater than or equal to the actual
coasting time can result in compressor damage.
The Alarm and Trip Settings Page SYSTEM INFO SETTINGS

provides the means for changing Alarm Trip
the analog health monitoring Stage 1 Temperature 120 125
values. The number of inputs Stage 1 Vibration 0.80 1.00
varies depending upon the number Stage 2 Temperature 120 125
Stage 2 Vibration 0.75 0.95
of compression stages and Oil Pressure 18 16
optional inputs. Additional pages High Oil Temperature 120 125
will be added as needed after this Low Oil Temperature 100 95
page. All line items are changeable Load Selected
for the Alarm and Trip setpoints. Loaded Remote 6/6
Settings Folder - Page 6: Alarm and Trip
WARNING
Setting Trip values outside the range specified on the drawings can result in
compressor damage.
22204796 Rev. B, Version 3.10

General Sequence of Operation
To start and load a

compressor follow
steps 1, 2, 3 and 4 CENTAC  Microcontroller
System
Valve 95
1 Press Pressure
Valve 0
Reset Motor
Current 173.4
22JUL96 12:00:00
2 Look for Loaded Load Selected

Remote 1/2
"Ready"
3 Press Start
4 Press Load
Press Unload,
To unload and stop 5 wait 20 seconds
a compressor follow
steps 5 and 6 6 Press Stop

for Motor Driven Packages
Not Ready
Ready
Full Load
Starting
Unloaded
Unloading
Loading
Loaded
Loaded
Unloaded
Coasting
MinLoad
MaxLoad
Waiting
Unload
Motor Full Load Amps Plus Service Factor
Motor
Current
amps, % MaxLoad Setpoint Amps
100 Motor Full Load Amps
MinLoad Setpoint Amps

Load
Any
Stops or
Trips
No
Stops or
Trips Start Unloaded Amps
Zero Amp Offset

0
Power
On Stopped Rotating
22204796 Rev. B, Version 3.10

Indicator, Switch and Light Layout

In addition to the CMC OUI there may be a variety of indicators, switches, and lights
mounted on the control panel door. In conjunction with the CMC OUI these devices make
up the User Interface for the CMC. A typical device layout consists of the following lights,
push buttons, and selector switches.
Lights
The lights provided are the green CONTROL POWER ON light, which is integral to the
CONTROL POWER OFF/ON switch, the amber PRELUBE PUMP RUNNING light and the
red TROUBLE INDICATION light.
Push Buttons
The red EMERGENCY STOP push button stops the compressor any time that it is pressed.
This push button is used to initiate a stop in the case of an emergency.
Switches
The CONTROL POWER OFF/ON selector switch turns the panel power on or off
CMC Tuning Procedures

When commissioning a new compressor, troubleshooting an existing compressor, or tuning
a system, the following procedures may be required. The procedures are performed, and
any changes required are made through the CMC OUI. For instructions on how to use the
OUI refer to the section titled User Interface. The following figure will be referenced in the
procedures.
PT
1 PT Bypass
2 Valve
Pneumatic Tubing
Block
Valve
4-20 mA Check
Base
Valve
Control
Module CT Starter
Motor Compressor
Plant Air System

Inlet
Valve
4-20 mA
Inlet Filter
Figure 18: Plant Air System
Setting MaxLoad
The MaxLoad Setpoint keeps the motor within the allowable current range. To determine
the value for MaxLoad, an Adjusted Service Factor (ASF) is multiplied by the motor full load
22204796 Rev. B, Version 3.10

amps (FLA). The (ASF) is found by obtaining the motor service factor from the motor
nameplate and selecting the adjustment factor from the table below. The motor full load
amps is found on the motor nameplate.
Motor Service Factor Adjusted Service Factor
1.15 1.05
1.25 1.10
Example: MaxLoad = FLA X ASF

FLA: 134 Amps
Adjusted service factor: 1.05
MaxLoad: 140
Setting MinLoad
MinLoad establishes the minimum flow through the machine when loaded; it is the
maximum point of inlet valve throttling. If system demand is below this throttle point, the
compressor must bypass air or unload. If flow were allowed to go below MinLoad, the
machine would eventually cross the surge line and surge. By stopping inlet valve throttling
at MinLoad the machine is kept out of surge. To find the MinLoad setting, the machine is
run into the surge line, and the value of load (amps, kilowatts, SCFM) at surge is recorded.
The recorded value is then incremented by five percent and set as the value for MinLoad.
1. Before continuing this procedure, verify the following:
a) The inlet and bypass control valves have been calibrated.
b) The machine is running unloaded.
c) The block valve at the inlet to the plant air system (Figure 18) is closed.
d) The pressure setpoint is set to the pressure at which the machine is going to
operate.
2. Set initial MinLoad estimates.
a) In the Settings Folder, select the Edit Data cell for MinLoad.
b) Increment or decrement the value to achieve a value of approximately 95% of full
load amps.
3. Preset the manual bypass valve position to 100.
a) On the OUI select the Settings Folder and enable manual valve control by
highlighting the manual check box.
NOTE
When Manual is enabled, both control valves can be positioned while stopped, while
only the Bypass Valve can be positioned when Loaded.
b) Switch to the System Folder Page 1 and press the Enter Key to enable edit mode.
c) Use the horizontal navigation keys to select the bypass valve.
22204796 Rev. B, Version 3.10

d) Increment the value to position the valve to 100 percent.

4. Load the compressor by pressing the Load Key.
5. Find the throttled surge point.
a) Slowly decrement the bypass valve position until the last stage discharge pressure
equals the pressure setpoint.
b) Allow the system to stabilize at MinLoad. It the system does not stay at MinLoad,
slightly decrement the valve position to force the machine to throttle to MinLoad.
c) Decrement (MinLoad) 2%.
d) Verify the last stage pressure equals the pressure setpoint and adjust the bypass
valve position if necessary.
e) Repeat c) and d) until the compressor surges.
6. Increase MinLoad by five percent.
7. Exit MinLoad editing by pressing the Enter Key.
8. Unload the machine.
9. Disable manual valve control by unchecking the manual check box.
Setting MinLoad Surge Index Increment

When Surge Indexing is enabled (MinLoad Surge Index Increment is greater than zero), the
Index Increment value is the amount added to the MinLoad Control Setpoint upon a surge.
The MinLoad Control Setpoint will stop being incremented when and if the value reaches
MaxLoad.
Setting Surge Sensitivity

The Surge Sensitivity setting should be set sensitive enough to detect a surge, yet not
trigger on spurious noise in the system. To set the surge sensor the machine is forced to
surge by running the machine at MinLoad and the MinLoad setpoint is dropped until the
machine audibly surges. The process is repeated until the correct setting is found.
1. Before continuing this procedure, verify the following:
a) The plant can tolerate a pressure disturbance when the machine surges.
b) Surge Indexing (by placing MinLoad Surge Index Increment to zero) is disabled.
c) Surge Absorber is disabled.
d) The pressure setpoint is set to the pressure at which the machine is going to
operate.
e) The machine is running unloaded.
2. Set the initial Surge Sensitivity setting to 9.
a) In the Settings Folder, select the Edit Data cell for Surge Sensitivity.
b) Increment or decrement the value to achieve a setting of 9.
3. Press the Load Key.
22204796 Rev. B, Version 3.10

4. Run the compressor at MinLoad and system pressure setpoint pressure. The
machine can be forced to MinLoad and to maintain system pressure setpoint by either.
a) Running the plant at a higher pressure than pressure setpoint.
b) Decreasing load in the plant.
c) Verify the compressor is at pressure by observing the last stage pressure on
Page 2 of the Settings Folder.
5. Find the throttled surge point.
a) Select the MinLoad cell in the Settings Folder and slowly decrement the value until
the machine surges. Typically the machine will make a puffing or popping noise
upon surge, this is your indication surge has occurred.
6. Press the Unload Key.
7. Determine if Surge was recorded.
a) Inspect the Status Bar. If the message Surge Unload is displayed surge was
recorded, if the message is not displayed surge was not recorded.
8. Check the Surge Sensitivity setting.
a) If the surge was recorded, the setting may be correct or the Surge Sensor may be
too sensitive, skip to the too sensitive step, which follows.
b) If the surge was not recorded, the setting is not sensitive enough, skip to the not
sensitive enough step, which follows.
9. Surge Sensor too sensitive.
a) Select the Surge Sensitivity Setting in the Settings Folder.
b) Decrease the value for Surge Sensitivity by 0.1.
c) Press the Reset Key.
d) Skip to step 11.
10. Surge Sensor not sensitive enough.
a) Select the Surge Sensitivity Setting in the Settings Folder.
b) Increase the value for Surge Sensitivity by 0.1.
c) Press the Reset Key.
11. Repeat the procedure until the Surge Sensitivity setting is found which just catches a
surge but does not miss a surge.
a) Return to step 3.
12. Restore MinLoad value.
Tuning Stability
The CMC controls stability with four Proportion Integral Derivative (PID) control loops.
When the machine is running above the MinLoad point and below the MaxLoad point,
pressure is regulated with the Inlet Valve Pressure control loop. When the machine is
running at the MinLoad point, pressure is regulated with the Bypass Valve Pressure control
22204796 Rev. B, Version 3.10

loop and motor current is regulated with the Inlet Valve MinLoad control loop. When the
machine is running at MaxLoad motor current is regulated with the Inlet Valve MaxLoad
control loop. For each PID loop, Proportional, Integral and Derivative parameters are used
to stabilize the system. For a definition of the parameters and their effect on stability, refer
to the section titled “How does Constant Pressure Modulation Work.” The proportional and
integral terms are labeled by their respective loops, Inlet Valve, Bypass Valve, MinLoad,
and MaxLoad.
Calibrating the Control Valves

The purpose of this procedure is to position the inlet and bypass valves by opening and
closing each valve from the CMC analog outputs. The valves should be adjusted to
physically correspond with the valve positions displayed on the OUI.
1. Stop the compressor.
NOTE
Performing this procedure while the compressor is operating may cause serious
damage.
2. On the OUI enable Setpoint changes by entering the password on the Settings Folder.
3. Verify the OUI status bar displays “Ready” or “Not Ready”.
4. On the OUI select the Settings Folder and enable manual valve control by highlighting
the manual check box.
NOTE
When Manual is enabled, both control valves can be positioned while stopped, while
only the Bypass Valve can be positioned when Loaded.
5. Switch to the System Folder Page 1 and press the Enter Key to enable edit mode.
6. Use the horizontal navigation keys to select the valve requiring positioning.
7. Use the vertical arrows to increment and decrement the valve position sent to the
valve.
NOTE
For the Inlet and Bypass Valves, the displayed position corresponds to percent open.
8. Disable manual valve control by blanking the manual check box.
22204796 Rev. B, Version 3.10

Autodual Control Settings

For a detailed definition of the Autodual control mode refer to the section titled “Control
Methodology”. The procedure for tuning Autodual requires the setting of the following
variables:
Unload Point (Bypass Valve % Open)

The Bypass Valve Unload Point is selected to correspond to the check valve closing as
shown in Figure 18, since at this point the machine is not supplying the system. This
position is found by running the machine at MinLoad and monitoring the System and
Discharge pressures. When the System pressure is 5% of setpoint greater than the last
stage pressure as shown in the System Folder, the check valve is assumed to be closed.
Example: Given the following conditions the Unload Point would be set at 35.
Variable Case 1 Case 2
Pressure Setpoint 100 100
PT1 (system pressure) 100 100
PT2 (last stage pressure) 100 94
Bypass Valve Position 13 35
Assumed check valve position Open Closed
1. Run the machine at MinLoad by elevating the system pressure no more than 3% or
decrease the pressure setpoint no more than 3%.
2. Monitor the difference between the Discharge and System Pressures by using the
System Folder Pages 1 and 2.
3. When the Discharge Pressure is approximately 95% of setpoint, record the Bypass
Valve Position.
4. Enter the recorded Bypass Valve Position as the Unload Point.
Unload Delay Time (seconds)

The Unload Delay Timer should be set to prevent unloading during short excursions
through the Unload Point. Typically, when the check valve closes, system demand requires
the check valve to open again soon thereafter due to the demand being on the verge of
requiring the compressor. If the compressor had unloaded when the check valve first
closed, a reload would be immediately required and the machine would go through the
automatic unload/load cycle until demand was consistently low enough to keep the check
valve closed. For this reason, the timer is used to inhibit Unload until demand has
consistently remained low. This value should be set according to the customer’s
observation experience as to how often system demand changes impact the reloading of
the compressor.
Reload Percent
The Reload Percent determines the System Pressure at which the machine will
automatically load into the system. This value should be set according to the customer’s
minimum acceptable system pressure.
22204796 Rev. B, Version 3.10

Setting the Start Time

The Start Time is set to the transition time of a built-in reduced voltage starter or the
acceleration time of a customer supplied starter. This procedure requires the Inlet Unload
Position to have been set.
CAUTION
Damage to the starter contacts could result if starter transition occurs before
the compressor is up to full speed.
1. Initially set the Start Time to 25 Seconds.

2. Stop the compressor. Allow compressor to coast to a stop.
3. On the OUI record the time and press the start button.
4. Wait for the compressor to stop accelerating and again record the time.
5. Calculate the difference between the two values and enter as the Start Time.
Setting the CT Ratio

Locate the CT and find the rating, which is typically printed, on the side of the CT. Divide
the primary by the secondary and enter the value as the CT Ratio.
Example: CT is printed with 600:5, the value entered is 120.
Inlet Unload Position

The purpose of this variable is to set the inlet valve position when the machine is running
unloaded. For a description of the Unloaded state refer to the section titled “Unload”.
1. If the inlet valve is a butterfly type, enter an initial value for Inlet Unload Position of 15. If
the inlet valve is a inlet guide vane type, enter an initial value for Inlet Unload Position of
5.
2. Start the machine. If during startup the motor trips on overload, draws what is
considered excessive amperage or sounds labored, stop the machine and decrease the
Unload Position by 2 and restart the machine.
3. Run the machine in the Unloaded state and monitor the first stage pressure.
4. Adjust the Unload Position to achieve 1 PSIG on the first stage discharge, or until a
positive pressure is felt at the first stage condensate trap bypass.
5. If the inlet air temperature is relatively cold, increase the setting 2%, this will
accommodate hot day operation.
Setting Set Point Ramp Rate

Setpoint ramp rate determines the rate at which the machine transitions from unloaded to
loaded. The setting should be set as high as possible without creating excessive overshoot
when the machine enters the system.
1. Verify the machine is unloaded by the “Unloaded” message in the OUI Status Bar.
22204796 Rev. B, Version 3.10

2. Determine overshoot.
a) Load the machine.
b) Monitor the pressure overshoot.
3. If overshoot is excessive.
a) Decrease the Setpoint Ramp Rate.
b) Repeat step 2.
4. If overshoot is satisfactory and time to load is excessive.
a) Increase the Setpoint Ramp Rate.
b) Repeat step 2.
5. If overshoot is satisfactory and time to load is satisfactory the Setpoint Ramp Rate is
correct.
Alarm and Trip Settings

The values for vibration, temperature, pressure etc. alarm and trip setpoints are located on the
electrical schematic. These values determine when the controller will indicate an alarm or trip
condition.
WARNING
Setting Trip values outside the range specified on the drawings can result in
compressor damage.
22204796 Rev. B, Version 3.10

Troubleshooting
The following procedures provide direction on troubleshooting the CMC System, control
panel, and associated instrumentation. Faults are either Event Logged, which means the
fault is displayed in the INFO Folder on the OUI, or Non-Event Logged. The distinction
helps to expedite the troubleshooting process.
When a control system fault is suspected, the following diagram is used to categorize the
fault. The section following the diagram breaks each category down into specific items,
which can cause a particular fault.
A CONTROL
SYSTEM FAULT IS
SUSPECTED
THE FAULT IS LOGGED IN THE FAULT IS NOT LOGGED IN

THE EVENT LOG. THE EVENT LOG
COMPRESSOR RELATED I/O FAULT CONTROL PROBLEMS
Compressor fails to Load, fails to trip, fails to

Temperature, pressure, load, valve, etc.
Event correctly indicates a problem. start, surging, etc.
readings incorrect.
(Refer to the compressor operating manual) (Refer to the CMC Tuning Procedures section)
(Refer to the Input/Output (I/O) System)
STABILITY PROBLEMS CONTROLLER PROBLEMS
Inlet valve, bypass valve, or control variables OUI failed, BCM failed, UCM failed,
(mass flow, system pressure, Kw, amps) are Communications failed.
unstable.
(Refer to Controller Problems Section)
(Refer to the CMC Tuning Procedures Section)
Figure 19: Troubleshooting Tree
22204796 Rev. B, Version 3.10

Troubleshooting Example
The following example will serve as a guide to follow when troubleshooting specific
problems.
Problem Indication: Event Name Time Date
1 Low Oil Pressure Trip 09:18:44 0720
Plant air pressure is low and the CMC OUI is found 2
3
Reset key pressed
09:18:43 0720
09:18:34 0720
as shown. 4 Low Oil Pressure Trip 09:08:43 0720
6 Load key pressed 08:24:01 0720
7 Start key pressed 08:23:12 0720
Trip
Probable Cause Determination: Not Ready Remote 2/6
1. The machine Tripped on Low Oil Pressure, which means the oil pressure, was below
the Oil Pressure Trip Value. Figure 19 leads to the assumption that the problem is
either compressor or I/O related, because the fault is Event Logged. There are two
most likely causes for this event.
a) Actual oil pressure is low.
i) The prelube pump is found to be running and installation of a calibrated
pressure sensor shows the actual oil pressure to be above the Oil Pressure Trip
Value. Therefore, the mechanical system is operating correctly.
b) The value read by the CMC is incorrect.
i) The oil pressure value displayed on Page 2 of the System Folder shows the oil
pressure to be below the test sensor reading and erratic. Additionally, all other
analog input readings are normal and not erratic. Therefore, the problem can be
isolated to the oil pressure, analog input circuit.
ii) The Pressure Monitoring System (PMS) troubleshooting table, found in the
following section “The Pressure Monitoring System” identifies the probable
cause for an erratic reading as a loose wire/terminal/connector and specifies
Troubleshooting Procedure PMS #1 and 2 as the appropriate procedures.
Trouble Procedure Execution:
Step 1 of PMS #1 requires disconnecting of the pressure transducer (PT) wires at the
terminal strip. When this step is performed, one of the connections is found to be
intermittent. When the poor connection is corrected, the erratic reading on the OUI
becomes solid.
22204796 Rev. B, Version 3.10

Input/Output (I/O) System

Vibration Monitoring System (VMS)
Description:
The vibration transmitter is used to convert the proximity probe signal into a 4 -20 mA
signal, which is monitored by the CMC. The system is based on a 5 meter total electrical
length (vibration probe electrical length plus extension cable electrical length).
Component specifications: (5 meter)
Transmitter:
• 200 mv/mil = 0.2 volt per 0.001 in (0.0254 mm)
• 4 mil (0.1016 mm) scale
• 4-20 mA output
Probe:
• Gap setting 0.030 to 0.060 in (0.762 to 1.524 mm), see Service Hints for nominal gap
• Probe gap corresponds to 6 to 12 volts VDC
• Ohm value of 0.5 meter Probe is 4 ohms, +/- 0.5 ohm
Troubleshooting:
The following table identifies typical problems, probable causes, and appropriate
procedures for verifying the probable cause:
Typical Problem Probable Cause Troubleshooting Procedure
Zero OUI readout Open circuit/cable disconnected VMS #2, 3, 4
(when compressor is Loss of power to transmitter VMS #1
running) Malfunctioning transmitter VMS #2
Transmitter not calibrated VMS #2
Erratic OUI readout Loose wire/terminal/connector VMS #2, 3, 4
Incorrect OUI readout Any VMS #1, 2, 3, 4, 5
22204796 Rev. B, Version 3.10

Checking Vibration Transmitter Power VMS #1

1. Connect a DC voltmeter to the +
and - terminals of the
transmitter.
2. With control power on, there
XXXXX XXXXX XXXXX
XXXXX XXXXX XXXXX
should be approximately 24 VDC mA
VDC present at the terminals.

3. If approximately 24 VDC is not
Ω
present; see the section titled
VAC
mA COM V Ω
“Control Power System”.
NOTE: Under no circumstances (See electrical
should the vibration transmitter zero schematic for point).
or span be adjusted. Calibration of Vibration

the vibration transmitter requires transmitter
special tooling and calibration

fixtures. Contact the factory if
calibration is required.
Checking Vibration Circuit VMS #2

1. With control power on, check the dc
voltage at the COM and TEST terminals
on the transmitter. A reading of 6 to 12
VDC should be present [this corresponds
XXXXX XXXXX XXXXX
XXXXX XXXXX XXXXX
to a 0.030 to 0.060 inches (0.762 to VDC mA
1.524 mm)] probe gap.

2. If less than 6 volts is present the probe VAC Ω
mA COM V Ω
gap may be incorrect, or a short circuit
may exist. Check the cable connections
and cable.
3. If more than 12 volts is present the probe Compressor casing
gap may be incorrect, or an open circuit

may exist. Check the cable connections
and cable.
4. If no voltage exists, the transmitter may Vibration transmitter
be faulty. Remove control power and

swap connections with another
Vibration probe
transmitter and test.
Probe extension cable
22204796 Rev. B, Version 3.10

Check the Vibration Probe, and Cable VMS #3

1. Turn control power off and disconnect Probe connector
the probe extension cable from the

transmitter. XXXXX XXXXX XXXXX
2. Check resistance of the extension cable

XXXXX XXXXX XXXXX
VDC mA
Probe cable
and probe together, the reading should
be 5.3 ohms, +/- 0.7 ohm (5 meter VAC Ω
system) mA COM V Ω
Compressor
casing
Connect test lead

to outer shell.
Connect test lead

to inner pin.
Probe extension
cable
Vibration probe
Checking the Vibration Probe VMS #4

1. Turn control power off and disconnect
the probe extension cable from the
Connect test lead
to outer shell.
Probe connector
transmitter.
2. Check resistance of the probe alone, the XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
reading should be 4.0 ohms, +/- 0.5 ohm VDC mA

Probe cable
(0.5 meter probe)

VAC Ω
mA COM V Ω
Vibration probe
Connect test lead

to inner pin.
22204796 Rev. B, Version 3.10

Check the BCM VMS #5

1. With control power off connect a 4-20 mA simulator at the input points of the suspected
faulty device at connector J1, (see electrical schematic for connection points).
2. Turn control power on and vary the signal. If the value tracks according to the table
below, the wiring is faulty.
3. Verify the connector at J1 is fully seated. If the value does not track correctly, the BCM
may be faulty.
BCM
J2-Floating Analog Inputs, (4-20mA) Channels 1-2
J1-Grounded Analog Inputs,

(4-20mA) Channels 3-23
Pin 25
4-20 mA SURCE OR Pin 1
2 WIRE SIMULATOR
mA OUT
2 WIRE
OFF
MODEL CL-XXX
BATTERY
CHECK
00.0% - 100%
XXXXXX
555
LOOP
ON
00.0%
100%
DIAL
Conversion chart
mA percent Mils mA
(from simulator) (on OUI) (from simulator)
100% 4.0 20
50% 2.0 12
0% 0.0 4
22204796 Rev. B, Version 3.10

Temperature Monitoring System (TMS)

Description:
An RTD (Resistance Temperature Detector-2 Wire) with external transmitter is used by the
CMC for temperature monitoring. An RTD resistance (ohmic value) varies with temperature.
A transmitter for monitoring by the CMC analog input channel converts the resistance to a
4-20 mA signal.
Component specification:
Probe:
• 100 ohm Platinum resistance at 32 °F (0°C) with Temperature Coefficient Rating (TCR)
of 0.00385 Ohm/Ohm/Deg C
Transmitter:
• The transmitter may be mounted in the RTD connection head fitting or in the control
panel enclosure. The transmitter is supplied 24 VDC and outputs 4-20mA over a fixed
range of either 0 to 200°F (-17.7 to +93.3°C), or 0-500°F (-17.7 to +260°C).
Troubleshooting:
Typical Problem Probable Cause Troubleshooting
Procedure
High OUI readout High resistance connection TMS #4
Transmitter not calibrated TMS #3
RTD failure TMS #2
Transmitter failure TMS #3
Low OUI readout Transmitter failure TMS #3
RTD failure TMS #2
Transmitter not calibrated TMS #3
Erratic OUI readout Loose terminal connection TMS #4
RTD internal wire fault TMS #2
Transmitter failure TMS #3
Incorrect OUI readout Transmitter not calibrated TMS #3
RTD or transmitter failure TMS #2, 3
Any TMS #1, 2, 3, 4
22204796 Rev. B, Version 3.10

Checking for Power to the Temperature Transmitter TMS #1

1. Disconnect the wires at terminals #1 and #2 on the transmitter and connect a voltmeter
to these wires.
2. With control power on, there should be approximately 24 VDC present at the terminals.
3. If approximately 24 VDC is not present, see the section titled “Control Power System”.
BCM

Pin 25
Pin 1
XXXXX XXXXX XXXXX
XXXXX XXXXX XXXXX
VDC mA
123 4
VAC Ω
mA COM V Ω
RTD
Temperature transmitter
22204796 Rev. B, Version 3.10

Checking for a Faulty RTD TMS #2

1. Turn control power off.
2. Check ohms versus temperature. Use an
Ohmmeter and the following tables to
determine if the RTD is faulty. Vary the XXXXX XXXXX XXXXX
temperature to the RTD and check the XXXXX XXXXX XXXXX
ohms around the normal operating VDC mA
range.
VAC Ω
mA COM V Ω
Thermometer
RTD
32 DEGF
Ice water
22204796 Rev. B, Version 3.10

Degrees Fahrenheit versus Ohms value chart for 100 OHM Platinum RTD
°F 0 1 2 3 4 5 6 7 8 9
0 93.01 93.22 93.44 93.66 93.88 94.10 94.32 94.54 94.76 94.98
10 95.20 95.42 95.63 95.85 96.07 96.29 96.51 96.73 96.95 97.17
20 97.38 97.60 97.82 98.04 98.26 98.47 98.69 98.91 99.13 99.35
30 99.56 99.78 100.00 100.20 100.40 100.70 100.90 101.10 101.30 101.50
40 101.70 102.00 102.20 102.40 102.60 102.80 103.00 103.30 103.50 103.70
50 103.90 104.10 104.30 104.60 104.80 105.00 105.20 105.40 105.60 105.80
60 106.10 106.30 106.50 106.70 106.90 107.10 107.40 107.60 107.80 108.00
70 108.20 108.40 108.70 108.90 109.10 109.30 109.50 109.70 109.90 110.20
80 110.40 110.60 110.80 111.00 111.20 111.50 111.70 111.90 112.10 112.30
90 112.50 112.70 113.00 113.20 113.40 113.60 113.80 114.00 114.30 114.50
100 114.70 114.90 115.10 115.30 115.50 115.80 116.00 116.20 116.40 116.60
110 116.80 117.00 117.30 117.50 117.70 117.90 118.10 118.30 118.50 118.80
120 119.00 119.20 119.40 119.60 119.80 120.00 120.20 120.50 120.70 120.90
130 121.10 121.30 121.50 121.70 122.00 122.20 122.40 122.60 122.80 123.00
140 123.20 123.40 123.60 123.90 124.10 124.30 124.50 124.70 124.90 125.20
150 125.40 125.60 125.80 126.00 126.20 126.40 126.60 126.90 127.10 127.30
160 127.50 127.70 127.90 128.10 128.30 128.60 128.80 129.00 129.20 129.40
170 129.60 129.80 130.00 130.30 130.50 130.70 130.90 131.10 131.30 131.50
180 131.70 132.00 132.20 132.40 132.60 132.80 133.00 133.20 133.40 133.60
190 133.90 134.10 134.30 134.50 134.70 134.90 135.10 135.30 135.50 135.80
200 136.00 136.20 136.40 136.60 136.80 137.00 137.20 137.40 137.70 137.90
210 138.10 138.30 138.50 138.70 138.90 139.10 139.30 139.60 139.80 140.00
220 140.20 140.40 140.60 140.80 141.00 141.20 141.40 141.70 141.90 142.10
230 142.30 142.50 142.70 142.90 143.10 143.30 143.50 143.80 144.00 144.20
240 144.40 144.60 144.80 145.00 145.20 145.40 145.60 145.90 146.10 146.30
250 146.50 146.70 146.90 147.10 147.30 147.50 147.70 147.90 148.20 148.40
260 148.60 148.80 149.00 149.20 149.40 149.60 149.80 150.00 150.20 150.50
270 150.70 150.90 151.10 151.30 151.50 151.70 151.90 152.10 152.30 152.50
280 152.70 153.00 153.20 153.40 153.60 153.80 154.00 154.20 154.40 154.60
290 154.80 155.00 155.20 155.40 155.70 155.90 156.10 156.30 156.50 156.70
300 156.90 157.10 157.30 157.50 157.70 157.90 158.10 158.40 158.60 158.80
310 159.00 159.20 159.40 159.60 159.80 160.00 160.20 160.40 160.60 160.80
320 161.00 161.30 161.50 161.70 161.90 162.10 162.30 162.50 162.70 162.90
330 163.10 163.30 163.50 163.70 163.90 164.10 164.30 164.60 164.80 165.00
340 165.20 165.40 165.60 165.80 166.00 166.20 166.40 166.60 166.80 167.00
350 167.20 167.40 167.60 167.80 168.10 168.30 168.50 168.70 168.90 169.10
360 169.30 169.50 169.70 169.90 170.10 170.30 170.50 170.70 170.90 171.10
370 171.30 171.50 171.80 172.00 172.20 172.40 172.60 172.80 173.00 173.20
380 173.40 173.60 173.80 174.00 174.20 174.40 174.60 174.80 175.00 175.20
390 175.40 175.60 175.80 176.00 176.30 176.50 176.70 176.90 177.10 177.30
400 177.50 177.70 177.90 178.10 178.30 178.50 178.70 178.90 179.10 179.30
410 179.50 179.70 179.90 180.10 180.30 180.50 180.70 180.90 181.10 181.30
420 181.50 181.80 182.00 182.20 182.40 182.60 182.80 183.00 183.20 183.40
430 183.60 183.80 184.00 184.20 184.40 184.60 184.80 185.00 185.20 185.40
440 185.60 185.80 186.00 186.20 186.40 186.60 186.80 187.00 187.20 187.40
450 187.60 187.80 188.00 188.20 188.40 188.60 188.80 189.00 189.20 189.40
460 189.70 189.90 190.10 190.30 190.50 190.70 190.90 191.10 191.30 191.50
470 191.70 191.90 192.10 192.30 192.50 192.70 192.90 193.10 193.30 193.50
480 193.70 193.90 194.10 194.30 194.50 194.70 194.90 195.10 195.30 195.50
490 195.70 195.90 196.10 196.30 196.50 196.70 196.90 197.10 197.30 197.50
500 197.70 197.90 198.10 198.30 198.50 198.70 198.90 199.10 199.30 199.50
22204796 Rev. B, Version 3.10

Degrees Celsius versus Ohms value chart for 100 OHM Platinum RTD
°C 0.00 0.62 1.23 1.85 2.47 3.09 3.70 4.32 4.94 5.56
-17.78 93.01 93.22 93.44 93.66 93.88 94.10 94.32 94.54 94.76 94.98
-12.22 95.20 95.42 95.63 95.85 96.07 96.29 96.51 96.73 96.95 97.17
-6.67 97.38 97.60 97.82 98.04 98.26 98.47 98.69 98.91 99.13 99.35
-1.11 99.56 99.78 100.00 100.22 100.43 100.65 100.87 101.08 101.30 101.52
4.44 101.74 101.95 102.17 102.39 102.60 102.82 103.04 103.25 103.47 103.69
10.00 103.90 104.12 104.34 104.55 104.77 104.98 105.20 105.42 105.63 105.85
15.56 106.07 106.28 106.50 106.71 106.93 107.14 107.36 107.58 107.79 108.01
21.11 108.22 108.44 108.66 108.87 109.09 109.30 109.52 109.73 109.95 110.16
26.67 110.38 110.60 110.81 111.03 111.24 111.46 111.67 111.89 112.10 112.32
32.22 112.53 112.75 112.96 113.18 113.39 113.61 113.82 114.04 114.25 114.47
37.78 114.68 114.89 115.11 115.32 115.54 115.75 115.97 116.18 116.40 116.61
43.33 116.83 117.04 117.25 117.47 117.68 117.90 118.11 118.32 118.54 118.75
48.89 118.97 119.18 119.39 119.61 119.82 120.04 120.25 120.46 120.68 120.89
54.44 121.11 121.32 121.53 121.75 121.96 122.17 122.39 122.60 122.81 123.03
60.00 123.22 123.43 123.65 123.87 124.08 124.30 124.51 124.73 124.94 125.16
65.56 125.37 125.58 125.79 126.01 126.22 126.43 126.65 126.86 127.07 127.28
71.11 127.50 127.71 127.92 128.13 128.35 128.56 128.77 128.98 129.20 129.41
76.67 129.62 129.83 130.04 130.26 130.47 130.68 130.89 131.10 131.32 131.53
82.22 131.74 131.95 132.16 132.38 132.59 132.80 133.01 133.22 133.43 133.65
87.78 133.86 134.07 134.28 134.49 134.70 134.91 135.12 135.34 135.55 135.76
93.33 135.97 136.18 136.39 136.60 136.81 137.02 137.24 137.45 137.66 137.87
98.89 138.08 138.29 138.50 138.71 138.92 139.13 139.34 139.55 139.76 139.97
104.44 140.18 140.39 140.60 140.81 141.02 141.24 141.45 141.66 141.87 142.08
110.00 142.29 142.50 142.71 142.92 143.13 143.34 143.55 143.76 143.97 144.18
115.56 144.39 144.59 144.80 145.01 145.22 145.43 145.64 145.85 146.06 146.27
121.11 146.48 146.69 146.90 147.11 147.32 147.53 147.73 147.94 148.15 148.36
126.67 148.57 148.78 148.99 149.20 149.41 149.61 149.82 150.03 150.24 150.45
132.22 150.66 150.87 151.08 151.28 151.49 151.70 151.91 152.12 152.33 152.54
137.78 152.74 152.95 153.16 153.37 153.58 153.78 153.99 154.20 154.41 154.62
143.33 154.82 155.03 155.24 155.45 155.66 155.86 156.07 156.28 156.49 156.69
148.89 156.90 157.11 157.32 157.52 157.73 157.94 158.15 158.35 158.56 158.77
154.44 158.98 159.18 159.39 159.60 159.80 160.01 160.22 160.42 160.63 160.84
160.00 161.05 161.25 161.46 161.67 161.87 162.08 162.29 162.49 162.70 162.91
165.56 163.11 163.32 163.52 163.73 163.94 164.14 164.35 164.56 164.76 164.97
171.11 165.17 165.38 165.59 165.79 166.00 166.20 166.41 166.62 166.82 167.03
176.67 167.23 167.44 167.64 167.85 168.06 168.26 168.47 168.67 168.88 169.08
182.22 169.29 169.49 169.70 169.90 170.11 170.32 170.52 170.73 170.93 171.14
187.78 171.34 171.55 171.75 171.96 172.16 172.37 172.57 172.78 172.98 173.19
193.33 173.39 173.59 173.80 174.00 174.21 174.41 174.62 174.82 175.03 175.23
198.89 175.44 175.64 175.84 176.05 176.25 176.46 176.66 176.86 177.07 177.27
204.44 177.48 177.68 177.88 178.09 178.29 178.49 178.70 178.90 179.11 179.31
210.00 179.51 179.72 179.92 180.12 180.33 180.53 180.73 180.94 181.14 181.35
215.56 181.55 181.75 181.95 182.16 182.36 182.56 182.77 182.97 183.17 183.38
221.11 183.58 183.78 183.98 184.19 184.39 184.59 184.80 185.00 185.20 185.40
226.67 185.60 185.81 186.01 186.21 186.41 186.62 186.82 187.02 187.22 187.43
232.22 187.63 187.83 188.03 188.24 188.44 188.64 188.84 189.04 189.25 189.45
237.78 189.65 189.85 190.05 190.25 190.46 190.66 190.86 191.06 191.26 191.46
243.33 191.67 191.87 192.07 192.27 192.47 192.67 192.87 193.08 193.28 193.48
248.89 193.68 193.88 194.08 194.28 194.48 194.68 194.88 195.09 195.29 195.49
254.44 195.69 195.89 196.09 196.29 196.49 196.69 196.89 197.09 197.29 197.49
260.00 197.69 197.89 198.09 198.29 198.49 198.70 198.90 199.10 199.30 199.50
NOTE: This chart converted from Fahrenheit chart using formula °C= ((°F-32)/1.8)
22204796 Rev. B, Version 3.10

Checking the RTD Transmitter TMS #3

1. With control power off, connect a 100-ohm resistor to terminals #3 and #4 of the
transmitter.
2. Turn control power on, the OUI reading should be 32°F (0°C) ±5%.
3. If the reading is not within specification, the transmitter may be faulty.
BCM

Pin 25
Pin 1
123 4 100
OHM
5%
Temperature transmitter
22204796 Rev. B, Version 3.10

Checking proper operation of the BCM and wiring TMS #4

1. Ensure control power is off. At the affected RTD transmitter, disconnect the wires at
transmitter terminal #1 and #2. Connect a 4-20mA source to these terminals (Observe
correct polarity). Power up the control panel and then vary the simulator output.
2. At 12 mA (50%) the OUI should read 1/2 the RTD transmitter range; 100 or 250°F (37.7
or 121.1°C). The readout should change as the simulator output is varied.
3. If the reading on the OUI is incorrect or does not change, turn control power off and
reconnect the transmitter, remove the wires for this transmitter from J1 and move the 4
to 20 mA simulator to the respective terminals at connector J1, (see electrical schematic
for connection points).
4. Turn control power on and observe the OUI readout while varying the 4-20mA. If the
reading is correct there is an open or short in the wire or terminals connecting the CMC
to the RTD transmitter. If reading is not correct the BCM may be faulty.
BCM

Pin 25
2 WIRE SIMULATOR
mA OUT
2 WIRE
OFF
MODEL CL-XXX
BATTERY
CHECK
00.0% - 100%
XXXXXX
555
LOOP
ON
00.0%
100%
DIAL
22204796 Rev. B, Version 3.10

Valve Control System (VCS)

Description:
The BCM generates a 4-20 mA signal for valve control. The signal is wired to the I/P
(current to pressure) transducer for conversion to a pneumatic signal for positioning the
inlet or bypass control valve.
Specification:
• 4-20mA input = 3 to 15 psi output
• 60 to 120 PSIG instrument air input to I/P
Troubleshooting:
IV or BV not operating Failure of BCM VCS #1
Positioner or actuator malfunction VCS #2
Failure of I/P VCS #2
22204796 Rev. B, Version 3.10

Checking proper operation of the BCM and wiring VCS #1

1. With control power off, lift the wires at J3 for the suspected circuit and install a test meter
capable of reading milliamps as shown below, (the pin numbers are found on the
electrical schematic).
2. Restore control power.
3. If the meter reads 4 mA , the BCM is satisfactory.
4. If 4 mA is not present, refer to the section titled “Control Power System”.
5. Restore connections.
6. Remove control power.
7. Lift wires at suspected I/P, and install meter as in previous step.
8. Restore control power.
If the meter reads 4 mA, the BCM and wiring is satisfactory.
BCM
J3-Analog Outputs, (4-20mA) Channels 1-4

Pin 25
Pin 1
Pin 1
XXXXX XXXXX XXXXX
XXXXX XXXXX XXXXX
VDC mA
VAC Ω
mA COM V Ω
22204796 Rev. B, Version 3.10

Checking proper operation of the I/P and positioner VCS #2

1. Connect a 4-20 mA simulator to the I/P.
2. Ensure instrument air is present at the supply connection on the I/P.
3. Vary the simulator between 4-20 mA. The output of the I/P and the positioner should
follow. If the valve tracks the 4-20 mA signal correctly the I/P and the positioner are
satisfactory.
BATTERY LOOP
CHECK ON
mA OUT 100%
OFF DIAL
2 WIRE 00.0%
XXXXXX
MODEL CL-XXX
00.0% - 100% INGERSOLL-RAND
Centrifugal Compressor Division
2 WIRE SIMULATOR
4-20 mA SURCE OR
Highway 45 South
Mayfield, KY. 42066
Parts Service (800) 247-8640
555
22204796 Rev. B, Version 3.10

Pressure Monitoring System (PMS)

Description:
A Pressure Transducer (PT) is used to convert pressure (psi) to a 4-20 mA signal for
monitoring by the CMC.
Component specification:
• 0-50 PSIG (344.75 kPa) range
• 0-200 PSIG (1379 kPa) range
• Power = 24 VDC
Troubleshooting:
Zero OUI readout Open circuit/cable disconnected PMS #1, 2
Loss of power to transmitter PMS #1
Malfunctioning transmitter PMS #3, 4
Erratic OUI readout Loose wire/terminal/connector PMS #1,2
Incorrect OUI readout Any PMS #1, 2, 3, 4
22204796 Rev. B, Version 3.10

Checking for Power to the Pressure Transmitter PMS #1

1. Ensure control power is off. Disconnect the wires at the suspect PT and connect a
voltmeter to these wires.
2. With control power on, there should be approximately 24 VDC present at the terminals.
3. If approximately 24 VDC is not present, see the section titled “Control Power System”.
BCM

Pin 25
Pin 1
XXXXX XXXXX XXXXX
XXXXX XXXXX XXXXX
SPAN
VDC mA
VAC Ω
INGERSOLL RAND
mA COM V Ω
22204796 Rev. B, Version 3.10

Checking proper operation of the BCM and wiring PMS #2

1. Ensure control power is off. Disconnect the wires at the suspect PT and connect a 4-20
mA source to the lifted wires (Observe correct polarity).
2. Restore control power and then vary the simulator output.
3. At 12 mA (50%) the OUI should read 1/2 the PT range. The readout should change as
the simulator output is varied.
4. If the reading on the OUI is incorrect or does not change, turn control power off and
reconnect the transmitter, remove the wires for this transmitter from J1 and move the 4-
20 mA simulator to the respective terminals at connector J1, (see electrical schematic for
connection points).
5. Turn control power on and observe the OUI readout while varying the 4-20 mA. If the
reading is correct there is an open or short in the wire or terminals connecting the CMC
to the PT. If the reading is not correct the BCM may be faulty.
BCM

Pin 25
2 WIRE SIMULATOR
mA OUT
2 WIRE
OFF
MODEL CL-XXX
BATTERY
CHECK
00.0% - 100%
XXXXXX
555
LOOP
ON
00.0%
100%
DIAL
22204796 Rev. B, Version 3.10

Quick check of the PT PMS #3

1. Connect an ohmmeter to the disconnected wires coming from the PT.
2. If there is no continuity either the wiring or the PT is faulty.
XXXXX XXXXX XXXXX
XXXXX XXXXX XXXXX
VDC mA
VAC Ω
mA COM V Ω
SPAN
INGERSOLL RAND
Functional PT test PMS #4

1. Remove control power.
2. Remove the PT and connect a regulated air supply to the pressure connection. Power
up the CMC and vary the regulated air supply. The OUI should read the pressure being
applied.
22204796 Rev. B, Version 3.10

Digital Input System (DIS)

Description:
The digital input devices associated with the CMC are on/off devices that turn on or off the
associated CMC digital input.
Typical digital device name and type:
1. Low seal air pressure (Pressure)
2. Low cooling water flow (Flapper)
3. Low oil level (Float)
4. High condensate level (Float)
5. Dirty inlet filter (Differential pressure)
6. Dirty oil filter (Differential pressure)
7. High motor temperature (Thermistor)
Troubleshooting:
False alarm or trip Faulty device DIS #1
Faulty wiring DIS #1
22204796 Rev. B, Version 3.10

Checking proper operation of the digital devices DIS #1

1. Verify approximately 24 VDC is present as described in the section titled
“Troubleshooting the Power System”.
2. If approximately 24 VDC is present, install a multimeter with VDC selected between J4
or J5 pin1 and the input pin (the input pin can be determined from the electrical
schematic, or wire number).
3. Ensure the digital device is not in the trip condition, the meter should read 0 VDC.
4. Actuate the switch, the meter should read approximately 24 VDC.
J6-RS232 Serial
Data Link (Display),
Female DB9 BCM
J5-Digital (Discrete)
Inputs (24 VDC),
Channels 9-16
Pin 1
XXXXX XXXXX XXXXX
Inputs (24 VDC),
XXXXX XXXXX XXXXX
Channels 1-8
VDC mA
Pin 1
VAC Ω
mA COM V Ω Seal Air Switch
J3-Analog Outputs
(4-20mA)
Channels 1-4
22204796 Rev. B, Version 3.10

Control Power System (CPS)

Description:
The control power system provides 24 VDC to the CMC system for processing logic,
displaying data, and monitoring instrumentation. The 24 VDC power supply feeds the Base
Control Module (BCM) at connector J10. Over current protection and power distribution are
performed as shown below:
J2 J1
AC2 pin 3
+24 VDC pins 11 thru 14 Power Supply
BCM shown
F1 cover removed
Return pins 7 thru 10 AC1 pin 1
Fuse 5A/250VAC, normal blo.
J12-Digital Output Power 120 VAC (Pin 1)
To OUI J2 pin 2
To OUI J2 pin 1 OUI Power
To Ground Bar
J10-Power Input (24 VDC)

F103
F102
F101
F100
J9-Current Transformer
(0-5 amp)
CPU Power
BCM
All BCM Fuses are 5x20mm,
GMA 1.5 amp, Fast Blow
Digital Input Power

J4 & J5 - Digital Input Power 24 VDC (pin 1)
Analog Input/Output Power
LEGEND:
Trace
Wire
J3- Analog Output Power 24 VDC (pins 2 & 8) J1- Analog Input Power 24 VDC (pin 26)
22204796 Rev. B, Version 3.10

Power Supply:
• Input power: 85-132 VAC, or 180-264 VAC (auto-selecting input), 2.5A RMS max, 47-63
Hz.
• Output power: 24 VDC, 4.3 A maximum at 50 °C.
Troubleshooting:
Procedure
All analog inputs are zero or negative on System Page No AC power CPS #1
No DC power CPS #2
No analog input CPS #5
power
OUI displays: “INGERSOLL-RAND Centrifugal No CPU power CPS #8
Compressor Division”
BCM problems CMCS #3
OUI is black No AC power CPS #1
No DC power CPS #2
No OUI power CPS #7
Event Log indicates all digital alarms and trips active No AC power CPS #1
No DC power CPS #2
No digital input CPS #3
power
All digital outputs not working No AC power CPS #1
No DC power CPS #2
No digital output CPS #4
power
All analog outputs not working No AC power CPS #1
No DC power CPS #2
No analog output CPS #6
power
No AC power CPS #1
1. Ensure control power is off.
2. Install a multimeter set for VAC between pins 1 and 3 at connector J1 on the power
supply.
3. Restore control power, the meter should read 120 VAC or 220 VAC depending upon
the rated supply power. The rated supply power can be verified from the electrical
schematic.
22204796 Rev. B, Version 3.10

No DC power CPS #2
2. Install a multimeter set for VDC between pins 11-14 and 7-10 at connector J2 on the
power supply.
3. Restore control power, the meter should read approximately 24 VDC. If approximately
24 VDC is not present, check F1 on the power supply, if fuse is good, the power supply
may be faulty.
5. Install a multimeter set for VDC between pins 1 and 2 at connector J10 on the BCM.
24 VDC is not present, check the wiring between the power supply and the BCM.
No digital input power CPS #3

2. Install a multimeter set for VDC between pin 1 at connector J4 on the BCM and the
ground bar.
24 VDC is not present, check F103 on the BCM, if F103 is good, check for DC power.
No digital output power CPS #4

2. Install a multimeter set for VAC between pin 1 at connector J12 on the BCM and the
ground bar.
3. Restore control power, the meter should read 120 VAC.
No analog input power CPS #5

ground bar.
No analog output power CPS #6

ground bar.
No OUI power CPS #7

2. Install a multimeter set for VDC between pins 1 and 2 at connector J2 on the OUI.
3. Restore control power, the meter should read approximately 24 VCD. If approximately
24VDC is present, check F2 on the OUI. If F2 is good, go to next step.
22204796 Rev. B, Version 3.10

No CPU power CPS #8

2. Verify approximately 24 VDC is present at J10.
3. Check F100, if F100 is blown the BCM must be replaced, not the fuse.
4. If F100 is not blown, and the BCM is not functioning, the BCM must be replaced.
22204796 Rev. B, Version 3.10

Controller Problems
Description:
The CMC System is generally comprised of a Base Control Module (BCM), Operator User
Interface (OUI), and Power Supply (PS). There are few user serviceable components within
the system; however, a brief understanding of the system will help in overall
troubleshooting. All components require 24 VDC and rely on hardware and software to
perform correctly, if the problem cannot be isolated to a power problem it is most likely a
hardware or software problem, which will require Ingersoll-Rand support to correct.
Component Specification:
• VDC power required
• Software required
Troubleshooting:
Procedure
BCM fault suspected No power CMCS #4
OUI is dim Wrong contrast selected CMCS #1
Backlight failing CMCS #1
OUI is black No power CMCS #2
OUI displays “INGERSOLL-RAND Cable disconnected CMCS #3
Centrifugal Compressor Division”
OUI displays “Status XXH” Many Refer to Status Codes
Where XX is a specific number under System Information
Section.
MODBUS communications problem No power CMCS #5
Many Refer to the UCM
Section.
22204796 Rev. B, Version 3.10

BCM Problems
BCM is not controlling CMCS #4
1. Check the CPU power as described in the section titled “Control Power System”.
OUI Problems
OUI is dim CMCS #1
1. Depress the contrast key to step to the desired brightness.
2. Replace the OUI backlight as described in the section titled “Backlight Replacement
Procedure”. If the backlight does not fix the problem the OUI may be faulty.
OUI is black CMCS #2

1. Check for OUI power as described in the section titled “Control Power System”. If
approximately 24 VDC is present, check F2. If F2 is O.K. the OUI may be faulty.
OUI displays “INGERSOLL-RAND Centrifugal Compressor Division” CMCS #3

1. Check the cabling between OUI J1 and BCM J6.
2. The BCM may require programming.
3. Check the BCM CPU power.
4. The BCM may be faulty.
UCM Problems
All UCM LED’s are not lit CMCS #5
1. Check for approximately 24 VDC at pins 1 and 2 at J3 on the UCM.
2. If power is present at J3 the UCM may be faulty.
22204796 Rev. B, Version 3.10

Options
This section details the various standard options that are available for the CMC. Some of
the options listed are provided standard on some models, and will be indicated as such.
Enclosures
The CMC has three panel enclosures available; NEMA 12 (IP 64), which is standard, and
optional NEMA 4 (IP 65) and NEMA 4X (IP 65). The panel is machine mounted. All
electrical devices are mounted and wired where practical.
NEMA 12 (IP 64)

NEMA 12 is the standard enclosure for all compressors with CMC panels. NEMA defines
this rating as "... intended for indoor use primarily to provide a degree of protection against
dust, falling dirt, and dripping non-corrosive liquids. They shall meet drip, dust, and rust-
resistance design tests. They are not intended to provide protection against conditions such
as internal condensation.” Typically this type of enclosure is applied for most indoor
applications.
Cooling Fan
The cooling fan is supplied on all standard CMC enclosures, where a wye-delta motor
starter is present, the Control Electrical Package is included, or the ambient temperature
exceeds 40°C keeps the internal temperature below the maximum operating temperature
allowed. This action effectively extends the operating life of the control components. A filter
and gasket are added to attain a NEMA 12 rating.
NEMA 4 (IP 65)

This optional enclosure type is applied for most outdoor applications. Indoor applications
that are subject to hose washing would also apply to this standard. NEMA defines this
rating as "... intended for indoor and outdoor use primarily to provide a degree of protection
against windblown dust and rain, splashing water, and hose directed water; and to be
undamaged by the formation of ice on the enclosure. They shall meet hose down, external
icing, and rust-resistance design tests. They are not intended to provide protection against
conditions such as internal condensation or internal icing."
The standard panel enclosure is replaced with a new box that meets the above
requirements. The User Terminal vinyl overlay and sealing bezel is door mounted and
allows direct interface with the environment. NEMA 4 rated lights, switches and buttons are
mounted directly through the panel door. A panel space heater and Vortex Tube Cooler are
added to accommodate changes in ambient temperatures.
NEMA 4X (IP 65)

Also an optional enclosure type that should be applied in the same type of NEMA 4
applications within corrosive environments. The basic difference between NEMA 4 and
NEMA 4X is that the panel enclosure is constructed with stainless steel.
22204796 Rev. B, Version 3.10

Space Heater
Required for NEMA 4 and NEMA 4X panels to protect the panel from internal condensation.
This option should also be used with NEMA 12 for unheated building applications.
Vortex Tube Cooler

This panel cooler is required on NEMA 4 and NEMA 4X enclosures to maintain the
operating temperature below the maximum. An adjustable thermostat is provided to open
and close a solenoid operated valve from the instrument air header in the panel. The cooler
works by converting filtered compressed air into a hot air stream and cold air stream. The
hot air stream is vented external to the enclosure and the cold air stream is directed into the
enclosure.
Type Z Purge
The CMC requires a Type Z Purge when the customer environment is Division 2. A Type Z
Purge reduces the classification within an enclosure from Division 2 too non-hazardous.
When provided, a NEMA 4 or NEMA 4X enclosure is required. Hand valve selectable quick
and slow purges, with flow meters are provided to regulate the amount of gas entering the
panel. A differential pressure switch is wired to a light on the front of the panel to indicate if
there is a loss of purge gas. A relief valve is installed to prevent over-pressurization and a
warning label, text below, is affixed to the front of the panel.
WARNING
Enclosure shall not be opened unless the area is known to be non-hazardous

or unless all devices within the enclosure have been de-energized. Power shall not
be restored after the enclosure has been opened until combustible dusts have been
removed and the enclosure re-pressurized.
Fused Control Power Disconnect

As a safety precaution, this option removes power from the panel before the door is
opened. By turning the rotary door handle, the panel power is terminated. If the disconnect
is to include fuse size provisions for the main motor starter, additional information is
required. The disconnect would have to be mounted external to the panel enclosure. The
short circuit capacity, maximum ground fault, motor full load amps, motor locked rotor amps
and motor voltage must be known to size the disconnect properly. Pricing varies depending
upon the size, amp rating of the fuse, which is required for protection.
NOTE
This option does not make fuse size provisions for the main motor starter.
22204796 Rev. B, Version 3.10

Control Electrical Package

The Control Electrical Package consists of a Control Transformer, Prelube Pump Starter,
Oil Heater Contactor(s) and Transient Voltage Surge Suppressor. This option allows the
customer to bring a single source of electrical power to the compressor to run all of the
compressor package accessories; thereby, making compressor installation easier.
Stage Data Package

For monitoring of interstage pressure and temperatures, the Stage Data Package can be
added. As standard, the CMC comes with temperature readout, alarm and trip for the next
to last compression stage and compressor discharge pressure indication. When selected,
each stage gets temperature and pressure measurements on the downstream side of each
stage's cooler. For compressors without built-in aftercoolers, the last stage diffuser
temperature is measured. Each temperature has readout, alarm and trip capability while the
pressures are readout only.
Alarm Horn
The optional alarm horn sounds any time there is an alarm or trip situation. The horn output
will pulse for an alarm and remain constant for a trip. This allows the operator to distinguish
between each fault type without viewing the OUI. The horn silence push-button is located
on the CMC faceplate to silence any audible devices connected to the CMC board.
Running Unloaded Shutdown Timer

The intent of this option is to save energy by shutting the compressor off during extended
periods of unloaded operation. When the running unloaded shutdown timer is enabled with
the RUNNING UNLOADED SHUTDOWN TIMER DISABLED/ENABLED selector switch,
the auto-dual control mode should be selected, this provides for automatic unloading of the
machine during periods of low demand.
Water Solenoid Post Run Timer

This optional panel function is used to shut off water flow to the air and oil coolers after the
compressor is stopped. It is accomplished by sending a signal to close the solenoid
operated water valve(s).
Panel Mounted Wye-Delta Starter

Main motor starter enclosed in the CMC panel. This feature allows the customer to wire the
compressor from a single source; thereby, eliminating most electrical wiring and starter
installation expense. These starters are available for compressors with motors up to 350
HP and 575 Volts.
N.O. Contact for Remote Indication of Common Alarm and

Trip
A normally open contact for individual remote indication closes whenever an alarm or trip
occurs. This allows a customer to have remote indication of compressor alarm, trip or both.
Power Regulating Constant Voltage Transformer

If the electrical power supplied to the CMC varies more than ten percent, this transformer
must be added to bring the voltage within the specification requirements.
22204796 Rev. B, Version 3.10

Automatic Starting
NOTE
Most electric motors are only rated for two cold starts or one hot start per hour. It is
the operator’s responsibility not to exceed the electric motor’s limitation. The control
system allows the compressor to be started when the compressor is ready, not the
motor.
Remote start and stop through hard wiring to the compressor control panel, communicating
through the MODBUS port via RS422/485, Auto-Hot Start and Auto-Cold Start are the four
options for automatically starting and stopping with the CMC. With each of these options a
REMOTE COMMUNICATIONS DISABLED/ENABLED or REMOTE FUNCTIONS
DISABLED/ENABLED, selector switch is provided on the device plate with a REMOTE
ENABLED light. Since each option performs basically the same function, only one should
be purchased for a single CMC. The specific method selected depends upon the
application.
Remote Start and Remote Stop – Hardwired

When this option is purchased, two digital inputs are configured on the CMC Base Control
Module, one for remote start and one for remote stop.
Remote Start Digital Input

This input is driven by a momentary contact closure of at least 120 milliseconds. For the
start to proceed, the panel power must be on, the compressor must be in the Ready state
(all utilities must be running and permissive functions satisfied) and the REMOTE
FUNCTIONS DISABLED/ENABLED selector switch is in ENABLED mode prior to
energizing the input.
Remote Stop Digital Input

This input is driven by a maintained contact closure. The remote stop input is always active;
that is, the remote stop can be initiated regardless of the REMOTE FUNCTIONS
DISABLED/ENABLED selector switch position.
Communications
Remote starting and stopping can be accomplished through the MODBUS communication
port in various ways. See the section on Communications that follows for these options.
Again, panel power must be on, all utilities must be running and permissive functions
satisfied in order for the start-up to proceed.
Auto-Hot Start
Normally purchased in multiple compressor applications where backup air is required, this
automatic starting option allows the compressor to be started when the system air pressure
is below a user selected set point pressure.
Panel power must be on, all utilities must be running, the AUTO HOT START
DISABLED/ENABLED selector switch must be in the ENABLED position and all permissive
functions satisfied in order for the start-up to proceed. Solenoid water valve(s) are provided
for the intercooler(s) to reduce water consumption when the compressor is not running. A
22204796 Rev. B, Version 3.10

post run timer is also included in the Auto Hot Start logic to de-energize the water solenoid
valves twenty minutes after a compressor stop or trip to allow the oil to cool.
Auto-Cold Start
This option is very similar to Auto-Hot Start with the exception that the compressor starts
with no initial panel power. An additional timer is added to simulate the start button being
pressed and another timer is added to bypass the low oil temperature function on start-up.
One additional solenoid valve is included for instrument air supply. The CONTROL POWER
OFF/ON selector switch label is modified to CONTROL POWER LOCAL/OFF/COLD
START. When in the COLD START position, the compressor is OFF and can be started
through the Auto-Cold Start function. As a safety precaution, an optional strobe light can be
provided to indicate that an automatic start is about to begin.
Remote 4-20 mA Pressure Setpoint

When the REMOTE FUNCTIONS DISABLED/ENABLED selector switch is in the ENABLED
position, the CMC will monitor the specified analog input for pressure setpoint. If this analog
input’s value minus the Pressure Setpoint (from the display) is greater than or equal to the
display’s Pressure Setpoint step value (default 0.1 psi), a remote setpoint change will be
requested. This request will be initiated, as long as there are no analog input error faults for
this channel, and the change made will rounded to the nearest step value (0.1) size. This
methodology prevents the control system from chasing an ever-changing analog input
value.
Ambient Control plus Parallel Valve Control Logic

Ambient Control
This feature uses Polytropic Head (or just Head) as the MinLoad control variable. By using
Head, a more conservative MinLoad setting can be established which contributes to energy
efficiency. For additional information on Polytropic Head, see section under SURGE
CONTROL / Control Methodology.
Polytropic Head may be selected as the MinLoad control variable for Pressure Control (the
standard process control for the CMC), or optional Flow Control. Polytropic Head may also
be selected as the MinLoad control variable for Steam and Gas Turbine Driven and Diesel
Driven Compressors.
Parallel Valve Control Logic

This feature includes a number changes to control logic to improve valve transitions.
• One feature is improved State Transitions. The overall effect will be better
response to system dynamics requiring state changes.
An example of this is inlet valve throttling. When the machine is rapidly throttling
from Loaded State to the MinLoad state, the inlet valve will transition to MinLoad
before actually reaching the Minload setpoint. The valve transition offset is a
function of the PID settings for the MinLoad and Loaded loops and the rate at which
the process control variable is rising. By making this transition early, improved
control response is achieved. In this case, undershoot of MinLoad would be
decreased and overshoot of the process variable would be decreased relative to
previous CMC releases.
• For installations with big, quick swings in load that get the check valve opened and
closed frequently a new Discharge Pressure Regulation feature may be selected
22204796 Rev. B, Version 3.10
to provide better pressure control. Previously these large changes required the
MinLoad to be set more conservatively. Otherwise if the controller could not react
fast enough the system would decay while closing the bypass valve.
This new control loop will regulate compressor discharge pressure when the
discharge check valve is closed. Adding this loop also eliminates windup of the
bypass valve and allow for quicker reentry into the system. This feature requires
configuration by an Ingersoll-Rand service technician.
• Typically, overshoot can occur when the system being regulated has a significant
change in dynamic response and the PID parameters are not changed accordingly.
For compressor control, this happens when the controller used the same bypass
valve PID values for control regardless of the check valve state. One way to handle
this is with the above Discharge Pressure Regulation feature previously described.
If the installation does not warrant setting up Discharge Pressure Regulation, the
Loading Ramp rate feature is used to accommodate this check valve complication.
The Loading Ramp feature minimizes overshoot upon a load command.
• An additional feature called Unloading Interrupt is also a part of the CMC. The
unloading state can now be interrupted by a load command and reload the machine
without completely unloading it.
• Deadband on Control Variables is another feature of Parallel Valve Control Logic.
This feature prevents valve oscillations when the Process Variable is steady state.
Steady state valve oscillation is primarily a result of the control valve’s inability to
position as finely as required by the PID control loop. A typical scenario would be
when the CMC commands the valve to open 0.05% and the valve opens 0.1%. The
valve now needs to close 0.05% but will likely close 0.1% causing the cycle to start
over. This feature requires configuration by an Ingersoll-Rand service technician.
22204796 Rev. B, Version 3.10

Mass Flow Control

Constant flow control is a performance control method for Centac air compressors.
Uncontrolled, the compressor's
discharge flow would rise and fall Natural
Pressure
along the natural performance Curve
curve as system flow demand Surge Line Design

Point
changed. Constant Flow control
Maximum
satisfies the constant flow Throttle Points
requirement. Discharge (MinLoad)

Pressure
Constant
This performance map shows Flow Line
Constant Flow control. Constant Unloaded

Flow control maintains the
compressor discharge flow into the
system at the Flow Setpoint as
entered into the CMC by the user. Natural
Once loaded, the compressor will Power
Curve
operate along the constant flow
Surge Line
line until the user presses the
Unload or Stop button.
Control is accomplished by Power at
Coupling
modulating the inlet valve within
the compressor's operating range.
When the compressor’s demand is
less than the minimum throttled Unloaded
capacity, constant flow is

maintained by modulating the Capacity
bypass valve and venting some or
all of the air to atmosphere. This Figure 20: Constant Flow Control
valve is opened just prior to reaching
the surge line. Whenever the bypass valve is open, the inlet valve maintains its position at
the minimum throttled capacity setting. Constant Flow provides a constant discharge flow
with variable pressure up to the natural surge point.
22204796 Rev. B, Version 3.10

Measuring the Flow

In order to maintain constant flow, the system discharge airflow must be measured. A flow
transducer is mounted in the customer’s piping upstream of the check valve.
CMC
4-20 mA
Bypass
Valve FT
4-20 mA Check
Base
Valve
Control
Module CT Starter FE
PT
x
Motor Compressor
Inlet
Valve
4-20 mA
4-20 mA
Figure 21: Measuring Flow

This transducer sends a 4-20 mA signal to the CMC board. The CMC compares the
measured flow to the flow setpoint entered into the CMC by the user through the Operator
User Interface (OUI). Depending upon the difference between these two values the CMC
will send a 4-20 mA signal to open or close the inlet and/or bypass valve to maintain the
specified compressor flow setpoint.
Steam and Gas Turbine Driven Compressors

The following describes the differences between the motor and turbine driven compressor
logic.
Performance Control
Motor Current, MinLoad and MaxLoad
Steam and gas turbines do not have motor current, MinLoad and MaxLoad operate
differently form the normal motor driven compressor. MinLoad uses an inlet valve position,
instead of amps, to determine when to transition from Inlet Valve Pressure control to
Bypass Valve Pressure control. When in MinLoad, the controller uses this valve position as
the setpoint for the Inlet Valve MinLoad PID loop. Since the controlled variable and the
setpoint variable are identical, the goal of tuning this loop is to get a steady output. The
default parameters will satisfy most all applications. The procedure for determining the
MinLoad point is the same for both motor and turbine driven units, except inlet valve
position is recorded instead of motor amps.
22204796 Rev. B, Version 3.10

CAUTION
Improperly tuning MinLoad PID values will result in unpredictable compressor

operation. If this situation arises, reset the PID values to the default values.
MaxLoad situations are detected on turbine driven compressors by low speed. The
MaxLoad setpoint is a speed below the rated speed and above the low speed alarm. This
speed is determined by adding an offset to the low speed alarm. This offset is the speed
that the governor can accurately control.
Surge Control
All surge related issues are identical to motor driven units with the exception of the
detection methodology.
How Surge is Detected

The CMC senses surge when the rate of change in last stage discharge pressure is greater
than the surge sensitivity setpoint value.
The difference between this and motor
driven units is that the motor driven units Compressor Operating States
uses rate of change in motor amps also. Turbine Driven Packages
+ Compressor
Compressor Operating Methodology
+ Stopped
Comparing the chart to the right for
Turbine driven compressor and Motor Waiting
driven compressor, the only state Not Ready
differences are the addition of the first Ready
three states under Rotating. These are
+ Rotating
Accelerate-1, Accelerate-2 and Slow
Rolling. Accelerate-1
Accelerate-2
Accelerate-1
Slow Rolling
This state is provided to give the operator
Starting
five minutes from the time the Start button
is pressed to get enough steam to the Unloaded
turbine to get the speed above the Zero A-D Unloaded
Offset Speed. This speed is defaulted to Surge Unload
15 rpm. If this speed is not achieved in
Loading
this time period, the event message
“Accelerate-1 Fail” will appear and the MinLoad
controller will trip the compressor. As Loaded
always, the compressor must be “Ready” Full Load
before the start button is pressed. The
MaxLoad
reason for the five-minute limitation is to
prevent the compressor from being ready Unloading
for an indefinite period of time. This Coasting
prevents the operator from forgetting that
the compressor is ready to accelerate. “Accelerate-1” could also be explained as
“accelerating to zero speed offset” or “waiting for compressor rotation”.
22204796 Rev. B, Version 3.10

Accelerate-2
After the transition to Accelerate-1 is complete, this state is initiated when rotation is
detected and the turbine has not reached the low trip speed. This state may be bypassed if
the turbine accelerates very quickly.
Once in this state, a sixty (60) second timer is initiated. If the speed does not get to the
minimum slow roll speed within this time period, the event message “Accelerate-2 Fail” will
appear and the controller will trip the package. This state is limited sixty (60) seconds to
prevent bearing damage from rolling the compressor at too low a speed. The bearing
design requires a minimum speed to form the oil film thickness required for proper bearing
operation. “Accelerate-2” could also be explained as “accelerating to minimum slow roll
speed”.
Slow Rolling
After the transition to Accelerate-2 is complete, this state is entered after the previous sixty-
second timer has elapsed and the speed is less than the low trip speed. The compressor
can operate in this “Slow Rolling” state indefinitely. While in this state, if the speed drops
below the minimum slow roll speed, the event message “Slow Roll Fail” will appear and the
controller will trip the compressor. If at any time during “Slow Rolling” the speed exceeds
the maximum slow roll speed, the compressor will transition to “Starting”. The Starting state
for turbine driven compressors is the same as for motor driven compressors.
Quick Start Turbines

Quick Start turbines may skip “Accelerate-2” and “Slow Rolling” or just “Slow Rolling”
because of the acceleration characteristics. The acceleration sequence depends upon the
acceleration characteristics for a given turbine.
Operator User Interface (OUI)

Status Bar
Motor driven compressors have an optional Compressor Status Field for Start Disabled.
This field is standard for turbine driven compressors and it means that the turbine trip and
throttle valve limit switch has not been made.
System Folder
Replacing “Motor Current “with” Compressor Speed” on Page 1 is the only modification to
this folder.
Info Folder
The events “Starter Failure” and ”Loss of Motor Current have been deleted from the
possible event list. The following events have been added.
22204796 Rev. B, Version 3.10

Possible Events List

Event Name Description
Accelerate-1 Fail The zero offset speed has not been achieved before the end of the five-minute timer.
Accelerate-2 Fail The minimum slow roll speed has not been achieved before the end of the one-minute timer.
Driver Trip The trip and throttle valve limit switch has been latched, then unlatched.
Governor Common Trip The governor has tripped.
High Speed Alarm The indicated speed is greater than or equal to the High Speed Alarm setting.
High Speed Trip The indicated speed is greater than or equal to the High Speed Trip setting.
Illegal Rotation Rotation has been detected when in “Stopped”.
Low Speed Alarm The indicated speed is less than or equal to the Low Speed Alarm setting.
Low Speed Trip The indicated speed is less than or equal to the Low Speed Trip setting.
Slow Rolling Fail The minimum slow roll speed was not maintained during “Slow Roll”.
Starting Fail The low trip speed was not achieved before the end of the Starting Timer.
TTV Switch Fault The trip and throttle valve (TTV) limit switch is made when the (TTV) solenoid is de-energized.
Settings Folder
For Page 2, Anti-Surge and Driver Over-Load Protection …
1. “MaxLoad (HLL), amps” is replaced with “MaxLoad (HLL), rpm”.
2. “User Setpoint (TL), amps” is replaced with “User Setpoint (TL), IV Pos %”.
3. “Control Setpoint, amps” is replaced with “Control Setpoint, IV Pos %”.
4. “Surge Index Increment, amps” is replaced with “Surge Index Increment, IV Pos %”.
For Page 5, Miscellaneous
1. “CT Ratio” is removed.
2. “Motor Failure Trip Enable” checkbox is removed.
22204796 Rev. B, Version 3.10

General Sequence of Operation

for Turbine and Diesel Driven Packages
Not Ready
Ready
Full Load
Starting
Unloaded
Unloading
Loading
Loaded
Unloaded
Coasting
MaxLoad
MinLoad
Waiting
Any
Mechanical Trip (110%) Stops or
Overspeed Trip (108%) Trips
Overspeed Alarm (105%)
Rated "Full Load" (100%)
MaxLoad (HLL)
Low Alarm (95%)

Low Trip (93%)
SPEED
Maximum Slow Roll (50%)
No
Minimum Slow Roll (25%) Stops or
Trips and
Latch Start
Zero Speed Offset (15 rpm)

(0%)
Power
On
Stopped Rotating
Starting Methodology
1. The panel power is turned on. The compressor is WAITING.
2. The CMC Panel mounted switch for DRIVER SPEED RATED/IDLE (when supplied for
an electronic governor) should be put into the IDLE position. This switch is wired to a
discrete input (Driver Speed Rated/Idle) in the CMC and is sent on the discrete output
(Driver Speed Rated/Idle) to the governor.
3. When the two-minute waiting timer has expired, the compressor is NOT READY.
22204796 Rev. B, Version 3.10

4. Reset the governor to clear any trip signals. This may be accomplished with the digital
output (Reset – Momentary). If an electronic governor exists, a discrete output signal
(Common Trip) is sent from the governor to a discrete input signal on the CMC when
the governor needs to trip the compressor. If no electronic governor exists, a jumper
must be installed on the CMC board.
Adaptive StartingTM Techniques
Low Trip (93%)
Starting Starting Starting
SPEED
Slow Rolling
Maximum Slow Roll (50%)
Accelerate-2 Accelerate-2
Minimum Slow Roll (25%)

Accelerate-1 Accelerate-1 Accelerate-1
Zero Speed Offset (15 rpm)

(0%)
5. When NO Trips exist (compressor and turbine), the CMC energizes the turbine’s trip
and throttle valve (TTV) solenoid. This is accomplished through a discrete output (Driver
Permissive) from the CMC to the TTV solenoid.
6. At this point, the compressor is NOT READY, Driver Disabled.
7. When the TTV solenoid is energized, the turbine trip valve can be latched.
8. When the turbine trip valve is manually latched, the turbine trip valve’s limit switch will
be energized. This signal is sent to a discrete input (Trip and Throttle Valve Limit
Switch) on the CMC.
9. When the limit switch is energized and no stop command is pending, the compressor
will be READY. This state may be maintained indefinitely.
10. The Start Key is pressed on the compressor. The digital output (CR1) is energized to
actuate the solenoid operated steam valve and the digital output (Start – Momentary) is
energized. A timer (five minute maximum) is started. At this point, enough steam should
be applied to the turbine to get the speed above the zero speed offset. This period is
ACCELERATE-1.
11. Once the zero speed offset has been established, a one minute timer is provided to
prevent compressor pinion damage from rotating the pinions at too low a speed for an
excessive time. The compressor bearings are designed to have a minimum oil film
pressure created by a minimum rotating pinion speed. Therefore, we must not stay at
22204796 Rev. B, Version 3.10

too slow a speed for an extended period. This is ACCELERATE-2. The turbine must
reach the Minimum Slow Roll Speed (approximately 25% of Full Speed) to continue.
12. Once the turbine gets past the Minimum Slow Roll Speed and is less than the Maximum
Slow Roll Speed (approximately 50% of Full Speed), the turbine is in the slow rolling
zone and the compressor is SLOW ROLLING. The User may leave the compressor in
this mode indefinitely. The CMC monitors the compressor speed (through the speed
analog input) in this mode. The Idle/Rated Driver Speed switch is turned to the Rated
position.
13. When the turbine speed exceeds Maximum Slow Roll Speed, the Starting Timer begins
(60 seconds maximum) and is STARTING. This is the same time for motor driven
compressors; therefore, the User must put enough steam to the turbine to get the speed
above the low trip speed before the timer expires. At this point, the compressor has
started and runs as described elsewhere.
Instrumentation for Turbine Driven Compressors

Centac Microcontroller
Discrete Outputs (DO)

CR1
TTV Solenoid Energize (Driver Permissive)
TTV Limit Switch
Start - Momentary
Stop - Momentary
Reset - Momentary
Driver Speed Rated/Idle
DI Discrete Inputs (DI)
DO Common Trip
Driver Speed
Rated/Idle
Switch
Electronic on Panel
Governor Door
AO Analog Input (AI)

Speed
AI
Speed
Turbine Compressor
TTV Solenoid
Manual Latch
Limit Switch
Steam
Throttle Valve
Trip Valve
Solenoid Steam Valve
22204796 Rev. B, Version 3.10

Diesel Driven Compressors

Diesel driven compressors have similar characteristics as the turbine driven compressors.
The differences are…
1. “Idle/Rated Driver Speed” discrete input and discrete output are eliminated.
2. “Start – Momentary”, “Stop – Momentary” and “Reset – Momentary” discrete outputs
are eliminated.
3. “Driver Permissive” discrete output is wired to the “Trip and Throttle Valve Limit
Switch” discrete input.
22204796 Rev. B, Version 3.10

Communication
Customers may want to communicate to the CMC control systems for remote compressor
control and monitoring. This communication capability provides for flexibility in the
customer's compressed air operation through remote start and stop, data gathering for
preventative maintenance, and incorporation into plant-wide control system.
The major avenue for communicating with the CMC is via MODBUS protocol over an
RS422/485 hardware link. This requires hardware for the control panel, and a
communications device with the appropriate driver software to perform the desired panel
functions. The RS422/485 interface can communicate with any serial device that has an
RS422 or RS485 port. The customer or his representative must write system software to
suit his individual needs for remote control and monitoring. Since the customer writes this
interface, the system can be as flexible as the customer desires.
Human Machine Interface (HMI) Systems

Air System Controller (ASC) and Air System Manager (ASM) are software packages
available for compressors with CMC panels.
ASC and ASM are graphical integration software specifically developed for air compressor
systems. Both provide energy management through load sharing and reduction of air
bypass by using a minimum amount of energy to meet the system demand. The primary
goal of both systems is to maintain stable system pressure, to integrate, monitor and control
the compressed air system.
ASM is the integration of compressor control software in an off-the-shelf Supervisor Control
and Data Acquisition (SCADA) package that is available from various manufacturers. The
ASM provides more custom features than does ASC.
Both ASC and ASM provide a window into the compressor room by making the raw data
from compressors and other equipment available to plant operators and managers in
formats that are easy to understand.
Implementing the CMC in any HMI system may require additional hardware and/or software
upgrade.
Direct CMC Communications with RS422/485

For the descriptions that follow, a serial device can be a Personal Computer (PC),
Programmable Logic Controller (PLC), Distributed Control System (DCS) or any other
device that can transmit, receive and interpret an RS422/485 formatted signal over a
hardware link. In the descriptions that follow, the PC and PLC serial devices are not specific
to manufacturers or operating systems.
There are many ways of interfacing to CMC control systems through an RS422/485 port.
Most of the following methodologies are currently available; but please be aware, other
possible configurations can exist.
All RS422/485 interfaces require custom interface software and custom application
software. The interface software allows a specific serial device and operating system to
transmit, receive and interpret data from a CMC control system. The application software
tells the CMC control system what to do; for example, start compressor when ready, stop
compressor after midnight and retrieve the current data and save to a disk file.
22204796 Rev. B, Version 3.10

Currently there are hundreds of different serial devices using different operating systems
and languages in the industrial equipment world. Therefore, the practicality of having an
interface for many systems is limited. Custom interfaces must be written as required by the
hardware and operating system used.
The capabilities of the hardware and the imagination of the developer only limit the
application software. For example, one developer may have two compressors. In this
application the developer wants a screen to display the compressor interstage pressure
and temperatures for both machines with various other compressor data. A second
developer has five compressors. He also wants to display the same data, but this time for
all five machines. The only way this is done is through changing the application software
(custom modification).
The developer may write functions to read and display data, log that data to some magnetic
media for storage, change compressor set points, sequence the compressors for efficient
operation and network additional devices, such as pumps, dryers, etc., into the system. All
of these functions require specially written application software for the intended use.
The CMC-MODBUS Interface

Introduction
The CMC can communicate with other devices over a variety of communications standards.
Supported standards, or protocols, include RS-232, IRBUS (Ingersoll-Rand Proprietary),
and Modicon’s MODBUS. The built-in ports on the CMC’s optional Universal
Communication Adapters access communications. The CMC-MODBUS Interface defines
the message structure that a CMC uses to exist on a MODBUS network. This interface will
allow the MODBUS network to gather information and control the compressor.
NOTE
Unless specified otherwise, numerical values (such as addresses, codes, or data) are
expressed as decimal values in the text of this section. They are expressed as
hexadecimal values in the message fields of the examples.
22204796 Rev. B, Version 3.10

In order to communicate over other types of

networks, a network adapter must be used. The Query
information presented in the following sections does
not include MODBUS protocol details like framing Master Slave
messages and calculating checksums. This detailed
information can be obtained from Schneider Device Device
Address Address
Automation’s MODBUS PROTOCOL Manual,
Chapters 1 through 6. This can be obtained through Function Function
Code Code
the Internet at “www.modicon.com”.
Data Byte
Address Count
Serial Modes
MODBUS Controllers can be setup to communicate Data Data
on MODBUS networks using either of two
transmission modes: ASCII or RTU. The CMC CRC CRC
supports only the RTU mode. The user must

specify the serial port communication parameters
Response
(baud rate, parity mode, etc.) during configuration of
each CMC. The mode and serial parameters must
be the same for all devices on a MODBUS network. Figure 22: MODBUS Messages
MODBUS Messages
A MODBUS network uses a master-slave relationship. The CMC always acts as a slave
device. The slave cannot initiate a message, and returns a message (response) only to
queries (reads) that are addressed to them individually. For example, a force coil command
(write to module) that is broadcast to all MODBUS devices would not get a response.
Responses are not returned to broadcast writes from the master.
Device Address
This address is the physical address of the Universal Communication Module (UCM) for the
compressor. This address must be unique in the MODBUS network. The valid range for this
address is 01-FF (hexadecimal). NOTE: 00 (hexadecimal) is reserved for broadcast.
Configuration of the slave address is available through the Ingersoll-Rand Service Tool and
will be provided by a certified Ingersoll-Rand Service Representative.
Function Code
The listing below shows the function codes that are supported by the CMC. Additional detail
about each function is provided in sections that follow.
Function Code Function Code Function Name

(decimal) (hex)
1 01 Read Coil Status
2 02 Read Input Status
3 03 Read Holding Registers
4 04 Read Input Registers
5 05 Force Single Coil
6 06 Preset Single Register
15 0F Force Multiple Coils
16 10 Preset Multiple Registers
22204796 Rev. B, Version 3.10

Data Addresses
Addresses that contain the data type and a four-digit number are referred to as absolute
(e.g., address 30232, where 3 is the data type for a input register and 0232 or 232 is the
address). Software products at the operator or user level use absolute addresses most
frequently.
The addresses that do not contain the type and are referenced to zero are referred to as
relative (e.g., absolute address 30232 would be relative address 231, remove the data type
3, holding register, and subtract 1 for referencing to zero). All data addresses in MODBUS
messages (typically, behind the scenes at the programming communication level) are
referenced to zero; that is, the first occurrence of a data item is addressed as item number
zero.
MODBUS Range MODBUS Range CMC Range CMC Range

Reference Data Type Absolute Relative Absolute Relative
Addresses Addresses Addresses Addresses
0x Coils 00001-09999 0000-9998 00001-09000 0000-8999
1x Discrete Inputs 10001-19999 0000-9998 10001-19000 0000-8999
3x Input Registers 30001-39999 0000-9998 30001-39000 0000-8999
4x Holding Registers 40001-49999 0000-9998 40001-49000 0000-8999
• Absolute address for Coil 00127 decimal is relatively addressed as coil 007E hex (126
decimal)
• Input register with absolute address of 30001 is relatively addressed as register 0000 in
the data address field of the message. The function code field that specifies reading or
writing data already specifies an input register operation; therefore, the 3x reference is
implicit.
• Holding register with an absolute address of 40108 is relatively addressed as register
006B hex (107 decimal)
Single Module Addresses
The addresses provided in this document are for compressors with a single Base Control
Module.
Multiple Module Addresses
For those systems that require multiple Base Control Modules, the addresses for the first
module will be as provided within this document. The addresses for the second module will
be provided as an engineering submittal.
Data
For both queries and responses, the data is in sixteen bit (two bytes, one word) chunks. For
each two byte word, the left most byte is the most significant. For each byte, the left most
bit is the most significant.
This portion of the message changes with each function code. See the detail that follows for
each function for the specifics of this message component.
Byte Count
The number of bytes contained in the data portion of the message. This is used on both
queries (reads) and responses.
22204796 Rev. B, Version 3.10

Cyclical Redundancy Check (CRC)

This portion of the message is used to prevent incorrect data from being used in the Master
or Slave because of communication errors.
Function Details
Function 01 - Read Coil Status
This function reads the state of one or more coils (MODBUS 0x references) in the slave
(CMC Base Control Module). For the CMC, these coils represent the Discrete (Digital)
Outputs, compressor operating state (see the Operator User Interface Status Bar for
definition), any compressor Trip condition and any compressor Alarm condition. If the
function returns a 1, the discrete output is on. If the function returns a 0, the discrete output
is off. Broadcast is not supported. Refer to the table on the next page for MODBUS
Absolute Addresses for each coil supported by the CMC-MODBUS Interface.
Absolute Relative Absolute Relative

Address Address Coil Name - Read Only* Address Address Coil Name - Read Only*
(decimal) (hex) (decimal) (hex)
00187 00-BA Digital Output, Channel 1 (J15-P7,8) 00203 00-CA Compressor State - Waiting
00188 00-BB Digital Output, Channel 2 (J15-P5,6) 00204 00-CB Compressor State - Coasting
00189 00-BC Digital Output, Channel 3 (J15-P3,4) 00205 00-CC Compressor State - Starting
00190 00-BD Digital Output, Channel 4 (J15-P1,2) 00206 00-CD Compressor State - Not Ready
00191 00-BE Digital Output, Channel 5 (J14-P7,8) 00207 00-CE Compressor State - Ready
00192 00-BF Digital Output, Channel 6 (J14-P5,6) 00208 00-CF Compressor State - Surge Unload
00193 00-C0 Digital Output, Channel 7 (J14-P3,4) 00209 00-D0 Compressor State - Autodual Unload
00194 00-C1 Digital Output, Channel 8 (J14-P1,2) 00210 00-D1 Compressor State - Unloading
00195 00-C2 Digital Output, Channel 9 (J13-P7,8) 00211 00-D2 Compressor State - Unloaded
00196 00-C3 Digital Output, Channel 10 (J13-P5,6) 00212 00-D3 Compressor State - Min load
00197 00-C4 Digital Output, Channel 11 (J13-P3,4) 00213 00-D4 Compressor State - Max load
00198 00-C5 Digital Output, Channel 12 (J13-P1,2) 00214 00-D5 Compressor State - Loading
00199 00-C6 Digital Output, Channel 13 (J12-P7,8) 00215 00-D6 Compressor State - Loaded
00200 00-C7 Digital Output, Channel 14 (J12-P5,6) 00216 00-D7 Compressor State - Full Load
00201 00-C8 Digital Output, Channel 15 (J12-P3,4) 00217 00-D8 Compressor State - Analog Input Failed
00202 00-C9 Digital Output, Channel 16 (J12-P1,2) 00218 00-D9 Any Compressor Trip
00219 00-DA Any Compressor Alarm
NOTE: (J15-P7,8) is interpreted as Connector J15, Pins 7 and 8 on the Base Control Module. * IMPORTANT: These coils are defined as
read only. If you decide to write to these coils, unexpected results could occur.
Example: Reading a Single Coil

After reviewing the Electrical Schematic for your compressor, you determine that the digital
output for the prelube pump is located on J12-P7,8 (Channel 13). From the table above, the
Absolute Address is decimal 00199 (Relative Address is hexadecimal 00C6) for the output
in question. Therefore, to read the state of the prelube pump output the following command
is issued (the following data are presented in hexadecimal format):
Number of
Device Function Address Coils CRC
Address Code Hi Lo Hi Lo Lo Hi
01 01 00 C6 00 01 1D F7
22204796 Rev. B, Version 3.10

The response from this command is:
Device Function Byte CRC

Address Code Count Data Lo Hi
01 01 01 01 90 48
The data (01) means that the discrete output is on, or the prelube pump is running.
Example: Reading Multiple Coils
To read all sixteen digital (discrete) outputs, the following command is sent:
Number of
01 01 00 BA 00 10 1C 23
where relative address 00-BA is for digital (discrete) output for Channel 1. The response
from this command is:

01 01 02 04-10 BA F0
To determine the state of each output, review the Electrical Schematic for your compressor.
For this example, you determine that the digital output for the prelube pump is located on
J12-P7,8 (Channel 13) and the digital output for the remote trouble contact is J15-P3,4
(Channel 3). The first hexadecimal data byte 04 (0000 0100 binary), represents the states
of the first eight digital (discrete) outputs (8-1). Therefore, for this example 04 means that
Channels 8, 7, 6, 5, 4, 2 and 1 are off and Channel 3 (compressor is in an alarm or trip
condition) is on. For the next eight channels (16-9) the hexadecimal data byte 10 (0001
0000 binary) means that Channels 16, 15, 14, 12, 11, 10 and 9 are off and Channel 13
(prelube pump is running) is on. The following table graphically depicts this example:
Response 8 7 6 5 4 3 2 1
Byte 1 0 0 0 0 0 1 0 0
Address C1 C0 BF BE BD BC BB BA
Response 16 15 14 13 12 11 10 9
Byte 2 0 0 0 1 0 0 0 0
Address C9 C8 C7 C6 C5 C4 C3 C2
A bit response of 1 means that the output is on and a response of 0 means that the output
is off.
Function 02 - Read Input Status

This function reads the state of one or more discrete inputs (MODBUS 1x references) in the
slave (CMC Base Control Module). For the CMC, these inputs represent the Discrete
(Digital) Inputs. If the function returns a 1, the input is on. If the function returns a 0, the
input is off. Broadcast is not supported. Refer to the table on the next page for MODBUS
Absolute Addresses for each discrete input supported by the CMC-MODBUS Interface.
22204796 Rev. B, Version 3.10

Absolute Address Relative Address Input Name - Read Only*

(decimal) (hex)
10171 00-AA Digital Input, Channel 1 (J4-P2)
10172 00-AB Digital Input, Channel 2 (J4-P3)
10173 00-AC Digital Input, Channel 3 (J4-P4)
10174 00-AD Digital Input, Channel 4 (J4-P5)
10175 00-AE Digital Input, Channel 5 (J4-P6)
10176 00-AF Digital Input, Channel 6 (J4-P7)
10177 00-B0 Digital Input, Channel 7 (J4-P8)
NOTE: (J4-P2) is interpreted as Connector J4, Pin 2 on the Base Control Module.
* IMPORTANT: These Digital Inputs are defined as read only. If you decide to
write to these Inputs, unexpected results could occur.
Example: Read Single Discrete Input

input for emergency stop push button is located on J4-P5 (Channel 4). From the table
above, the Absolute Address is decimal 10174 (Relative Address is hexadecimal 00AD) for
the input in question. Therefore, to read the state of the emergency stop push button the
following command is issued (the following data are presented in hexadecimal format):
Number of
Device Function Address Digital Inputs CRC
01 02 00 AD 00 01 28 2B

01 02 01 01 60 48
The data (01) means that the input is on, or the emergency stop push button is pressed.
Example: Read Multiple Discrete Inputs
The method for reading multiple Discrete Inputs is the same as reading multiple coils. See
the example for “Reading Multiple Coils”.
22204796 Rev. B, Version 3.10

Function 03 - Read Holding Registers

Reads the binary content of holding registers (MODBUS 4x references) in the slave (CMC
Base Control Module). For the CMC, these holding registers contain the Analog Output
values and Analog Alarm and Trip Setpoint values for all CMC inputs and outputs.
Broadcast is not supported.
The CMC is primarily a 32-bit floating-point microprocessor controller. And, since MODBUS
is designed to be a 16-bit system, the CMC supports two methods for determining the value
for each holding register (This also applies to Input Registers.)
NOTE
Since MODBUS is a 16-bit system, the programmer must get two 16-bit numbers and
combine them into one 32-bit floating-point number.
The first method uses two 16-bit integers to represent the integer and fraction part of the
value. The second method uses one 32-bit IEEE floating point number. (NOTE: For those
who would like to only get the 16-bit integer value, this will work well for most inputs;
however, the CMC has some inputs, like vibration, that are typically less than one.
Since the CMC has programmable analog and discrete inputs and outputs, the programmer
must use the electrical schematic supplied with the contract to determine which function
name and units of measure are associated with each input and output.
Refer to the table below for MODBUS Absolute Addresses for each Holding Register
supported by the CMC-MODBUS Interface.
22204796 Rev. B, Version 3.10

Signed Unsigned Signed

16 Bit Exponent 16 Bit Fraction IEEE 32-Bit Float
Absolute Relative Absolute Relative Absolute Relative
Holding Register Name - Read/Write Address Address Address Address Address Address
(Decimal) (hex) (Decimal) (hex) (Decimal) (hex)
Analog Output, Channel 1 (J3-P1,3) 40053 00-34 40054 00-35 43053 0B-EC
Analog Output, Channel 2 (J3-P4,6) 40055 00-36 40056 00-37 43055 0B-EE
Analog Output, Channel 3 (J3-P7,9) 40057 00-38 40058 00-39 43057 0B-F0
Analog Output, Channel 4 (J3-P10,12) 40059 00-3A 40060 00-3B 43059 0B-F2
Analog Input, Channel 1 (J2-P1,3) - High Trip Setpoint 40061 00-3C 40062 00-3D 43061 0B-F4
Analog Input, Channel 1 (J2-P1,3) - High Alarm Setpoint 40063 00-3E 40064 00-3F 43063 0B-F6
Analog Input, Channel 1 (J2-P1,3) - Low Alarm Setpoint 40065 00-40 40066 00-41 43065 0B-F8
Analog Input, Channel 1 (J2-P1,3) - Low Trip Setpoint 40067 00-42 40068 00-43 43067 0B-FA
Analog Input, Channel 2 (J2-P5,7) - High Trip Setpoint 40069 00-44 40070 00-45 43069 0B-FC
Analog Input, Channel 2 (J2-P5,7) - High Alarm Setpoint 40071 00-46 40072 00-47 43071 0B-FE
Analog Input, Channel 2 (J2-P5,7) - Low Alarm Setpoint 40073 00-48 40074 00-49 43073 0C-00
Analog Input, Channel 2 (J2-P5,7) - Low Trip Setpoint 40075 00-4A 40076 00-4B 43075 0C-02
Analog Input, Channel 3 (J1-P1) - High Trip Setpoint 40077 00-4C 40078 00-4D 43077 0C-04
Analog Input, Channel 3 (J1-P1) - High Alarm Setpoint 40079 00-4E 40080 00-4F 43079 0C-06
Analog Input, Channel 3 (J1-P1) - Low Alarm Setpoint 40081 00-50 40082 00-51 43081 0C-08
Analog Input, Channel 3 (J1-P1) - Low Trip Setpoint 40083 00-52 40084 00-53 43083 0C-0A
Analog Input, Channel 4 (J1-P4) - High Trip Setpoint 40085 00-54 40086 00-55 43085 0C-0C
Analog Input, Channel 4 (J1-P4) - High Alarm Setpoint 40087 00-56 40088 00-57 43087 0C-0E
Analog Input, Channel 4 (J1-P4) - Low Trip Setpoint 40091 00-5A 40092 00-5B 43091 0C-12
Analog Input, Channel 13 (J1-P21) - Low Alarm Setpoint 40161 00-A0 40162 00-A1 43161 0C-58
Analog Input, Channel 13 (J1-P21) - Low Trip Setpoint 40163 00-A2 40164 00-A3 43163 0C-5A
22204796 Rev. B, Version 3.10


Analog Input, Channel 14 (J1-P24) - High Trip Setpoint 40165 00-A4 40166 00-A5 43165 0C-5C
Analog Input, Channel 14 (J1-P24) - High Alarm Setpoint 40167 00-A6 40168 00-A7 43167 0C-5E
Analog Input, Channel 14 (J1-P24) - Low Alarm Setpoint 40169 00-A8 40170 00-A9 43169 0C-60
Analog Input, Channel 14 (J1-P24) - Low Trip Setpoint 40171 00-AA 40172 00-AB 43171 0C-62
Analog Input, Channel 15 (J1-P25) - High Trip Setpoint 40173 00-AC 40174 00-AD 43173 0C-64
Analog Input, Channel 15 (J1-P25) - High Alarm Setpoint 40175 00-AE 40176 00-AF 43175 0C-66
Analog Input, Channel 15 (J1-P25) - Low Alarm Setpoint 40177 00-B0 40178 00-B1 43177 0C-68
Analog Input, Channel 15 (J1-P25) - Low Trip Setpoint 40179 00-B2 40180 00-B3 43179 0C-6A
Analog Input, Channel 16 (J1-P28) - High Trip Setpoint 40181 00-B4 40182 00-B5 43181 0C-6C
Analog Input, Channel 16 (J1-P28) - High Alarm Setpoint 40183 00-B6 40184 00-B7 43183 0C-6E
Analog Input, Channel 16 (J1-P28) - Low Alarm Setpoint 40185 00-B8 40186 00-B9 43185 0C-70
Analog Input, Channel 16 (J1-P28) - Low Trip Setpoint 40187 00-BA 40188 00-BB 43187 0C-72
Analog Input, Channel 17 (J1-P29) - High Trip Setpoint 40189 00-BC 40190 00-BD 43189 0C-74
Analog Input, Channel 17 (J1-P29) - High Alarm Setpoint 40191 00-BE 40192 00-BF 43191 0C-76
Analog Input, Channel 17 (J1-P29) - Low Alarm Setpoint 40193 00-C0 40194 00-C1 43193 0C-78
Analog Input, Channel 17 (J1-P29) - Low Trip Setpoint 40195 00-C2 40196 00-C3 43195 0C-7A
Analog Input, Channel 18 (J1-P32) - High Trip Setpoint 40197 00-C4 40198 00-C5 43197 0C-7C
Analog Input, Channel 18 (J1-P32) - High Alarm Setpoint 40199 00-C6 40200 00-C7 43199 0C-7E
Analog Input, Channel 18 (J1-P32) - Low Alarm Setpoint 40201 00-C8 40202 00-C9 43201 0C-80
Analog Input, Channel 18 (J1-P32) - Low Trip Setpoint 40203 00-CA 40204 00-CB 43203 0C-82
Analog Input, Channel 19 (J1-P33) - High Trip Setpoint 40205 00-CC 40206 00-CD 43205 0C-84
Analog Input, Channel 19 (J1-P33) - High Alarm Setpoint 40207 00-CE 40208 00-CF 43207 0C-86
Analog Input, Channel 19 (J1-P33) - Low Alarm Setpoint 40209 00-D0 40210 00-D1 43209 0C-88
Analog Input, Channel 19 (J1-P33) - Low Trip Setpoint 40211 00-D2 40212 00-D3 43211 0C-8A
Analog Input, Channel 20 (J1-P36) - High Trip Setpoint 40213 00-D4 40214 00-D5 43213 0C-8C
Analog Input, Channel 20 (J1-P36) - High Alarm Setpoint 40215 00-D6 40216 00-D7 43215 0C-8E
Analog Input, Channel 20 (J1-P36) - Low Alarm Setpoint 40217 00-D8 40218 00-D9 43217 0C-90
Analog Input, Channel 20 (J1-P36) - Low Trip Setpoint 40219 00-DA 40220 00-DB 43219 0C-92
Analog Input, Channel 21 (J1-P37) - High Trip Setpoint 40221 00-DC 40222 00-DD 43221 0C-94
Analog Input, Channel 21 (J1-P37) - High Alarm Setpoint 40223 00-DE 40224 00-DF 43223 0C-96
Analog Input, Channel 21 (J1-P37) - Low Alarm Setpoint 40225 00-E0 40226 00-E1 43225 0C-98
Analog Input, Channel 21 (J1-P37) - Low Trip Setpoint 40227 00-E2 40228 00-E3 43227 0C-9A
Analog Input, Channel 22 (J1-P40) - High Trip Setpoint 40229 00-E4 40230 00-E5 43229 0C-9C
Analog Input, Channel 22 (J1-P40) - High Alarm Setpoint 40231 00-E6 40232 00-E7 43231 0C-9E
Analog Input, Channel 22 (J1-P40) - Low Alarm Setpoint 40233 00-E8 40234 00-E9 43233 0C-A0
Analog Input, Channel 22 (J1-P40) - Low Trip Setpoint 40235 00-EA 40236 00-EB 43235 0C-A2
Analog Input, Channel 23 (J1-P41) - High Trip Setpoint 40237 00-EC 40238 00-ED 43237 0C-A4
Analog Input, Channel 23 (J1-P41) - High Alarm Setpoint 40239 00-EE 40240 00-EF 43239 0C-A6
Analog Input, Channel 23 (J1-P41) - Low Alarm Setpoint 40241 00-F0 40242 00-F1 43241 0C-A8
Analog Input, Channel 23 (J1-P41) - Low Trip Setpoint 40243 00-F2 40244 00-F3 43243 0C-AA
Motor Current 40267 01-0A 40268 01-0B 43267 0C-C2
User Pressure Setpoint 40269 01-0C 40270 01-0D 43269 0C-C4
MinLoad (Throttle Limit, TL) 40271 01-0E 40272 01-0F 43271 0C-C6
MaxLoad (High Load Limit, HLL) 40273 01-10 40274 01-11 43273 0C-C8
Autodual Reload Percent 40275 01-12 40276 01-13 43275 0C-CA
Autodual Unload Point 40277 01-14 40278 01-15 43277 0C-CC
Autodual Unload Timer 40279 01-16 40280 01-17 43279 0C-CE
Pressure Setpoint Ramp Rate 40281 01-18 40282 01-19 43281 0C-D0
Inlet Valve Unload Position 40283 01-1A 40284 01-1B 43283 0C-D2
Start Timer 40285 01-1C 40286 01-1D 43285 0C-D4
CT Ratio 40287 01-1E 40288 01-1F 43287 0C-D6
Power On Hours 40297 01-28 40298 01-29 43297 0C-E0
Running Hours 40299 01-2A 40300 01-2B 43299 0C-E2
Loaded Hours 40301 01-2C 40302 01-2D 43301 0C-E4
Number of Starts 40303 01-2E 40304 01-2F 43303 0C-E6
22204796 Rev. B, Version 3.10


Inlet Valve, MaxLoad, Proportional Constant 40313 01-38 40314 01-39 43313 0C-F0
Inlet Valve, MaxLoad, Integral Constant 40315 01-3A 40316 01-3B 43315 0C-F2
Inlet Valve, MaxLoad, Derivative Constant 40317 01-3C 40318 01-3D 43317 0C-F4
Inlet Valve, MinLoad, Proportional Constant 40319 01-3E 40320 01-3F 43319 0C-F6
Inlet Valve, MinLoad, Integral Constant 40321 01-40 40322 01-41 43321 0C-F8
Inlet Valve, MinLoad, Derivative Constant 40323 01-42 40324 01-43 43323 0C-FA
Inlet Valve, Pressure, Proportional Constant 40325 01-44 40326 01-45 43325 0C-FC
Inlet Valve, Pressure, Integral Constant 40327 01-46 40328 01-47 43327 0C-FE
Inlet Valve, Pressure, Derivative Constant 40329 01-48 40330 01-49 43329 0D-00
Bypass Valve, Pressure, Proportional Constant 40331 01-4A 40332 01-4B 43331 0D-02
Bypass Valve, Pressure, Integral Constant 40333 01-4C 40334 01-4D 43333 0D-04
Bypass Valve, Pressure, Derivative Constant 40335 01-4E 40336 01-4F 43335 0D-06
Compressor Control Mode; 1=Modulate, 2=Autodual 40339 01-52 40340 01-53 43339 0D-0A
NOTE: (J1-P1) is interpreted as Connector J1, Pin 1 on the Base Control Module.
Example: See example for Function 04.

Function 04 - Read Input Registers
Reads the binary content of input registers (MODBUS 3x references) in the slave (CMC
Base Control Module). For the CMC, these input registers refer to the Analog Input values.
Broadcast is not supported.
The CMC is primarily a 32-bit floating-point microprocessor controller. And, since MODBUS
is designed to be a 16-bit system, the CMC supports two methods for determining the value
for each holding register. (This also applies to Input Registers.) The first method uses two
16-bit integers to represent the integer and fraction part of the value. The second method
uses one 32-bit IEEE floating point number.
NOTE
Since MODBUS is a 16-bit system, the programmer must get two 16-bit numbers and
combine them into one 32-bit floating-point number.
For those who would like to only get the 16-bit integer value, this will work well for most
inputs; however, the CMC has some inputs, like vibration, that are typically less than one.
22204796 Rev. B, Version 3.10


16-Bit Integer 16-Bit Fraction IEEE 32-Bit Float
Input Register Name - Read Only* Address Address Address Address Address Address
Analog Input, Channel 1 (J2-P1,3) 30003 00-02 30004 00-03 33003 0B-BA
Analog Input, Channel 2 (J2-P5,7) 30005 00-04 30006 00-05 33005 0B-BC
Analog Input, Channel 3 (J1-P1) 30007 00-06 30008 00-07 33007 0B-BE
Analog Input, Channel 4 (J1-P4) 30009 00-08 30010 00-09 33009 0B-C0
Analog Input, Channel 5 (J1-P5) 30011 00-0A 30012 00-0B 33011 0B-C2
Analog Input, Channel 6 (J1-P8) 30013 00-0C 30014 00-0D 33013 0B-C4
Analog Input, Channel 7 (J1-P9) 30015 00-0E 30016 00-0F 33015 0B-C6
Analog Input, Channel 8 (J1-P12) 30017 00-10 30018 00-11 33017 0B-C8
Analog Input, Channel 9 (J1-P13) 30019 00-12 30020 00-13 33019 0B-CA
Analog Input, Channel 10 (J1-P16) 30021 00-14 30022 00-15 33021 0B-CC
Analog Input, Channel 11 (J1-P17) 30023 00-16 30024 00-17 33023 0B-CE
Analog Input, Channel 12 (J1-P20) 30025 00-18 30026 00-19 33025 0B-D0
Analog Input, Channel 13 (J1-P21) 30027 00-1A 30028 00-1B 33027 0B-D2
Analog Input, Channel 14 (J1-P24) 30029 00-1C 30030 00-1D 33029 0B-D4
Analog Input, Channel 15 (J1-P25) 30031 00-1E 30032 00-1F 33031 0B-D6
Analog Input, Channel 16 (J1-P28) 30033 00-20 30034 00-21 33033 0B-D8
Analog Input, Channel 17 (J1-P29) 30035 00-22 30036 00-23 33035 0B-DA
Analog Input, Channel 18 (J1-P32) 30037 00-24 30038 00-25 33037 0B-DC
Analog Input, Channel 19 (J1-P33) 30039 00-26 30040 00-27 33039 0B-DE
Analog Input, Channel 20 (J1-P36) 30041 00-28 30042 00-29 33041 0B-E0
Analog Input, Channel 21 (J1-P37) 30043 00-2A 30044 00-2B 33043 0B-E2
Analog Input, Channel 22 (J1-P40) 30045 00-2C 30046 00-2D 33045 0B-E4
Analog Input, Channel 23 (J1-P41) 30047 00-2E 30048 00-2F 33047 0B-E6
CT Input (J9-P1,2) 30049 00-30 30050 00-31 33049 0B-E8
NOTE: (J1-P1) is interpreted as Connector J1, Pin 1 on the Base Control Module. * IMPORTANT: These Input Registers are defined as read only. If
you decide to write to these Input Registers, unexpected results could occur.
Example: Read Single Channel 16-Bit Integer and Fraction

After reviewing the Electrical Schematic for your compressor, you determine that the analog
input for System Pressure is located on J1-P1 (Channel 3). From the table above, the
Absolute Address is decimal 30007 (Relative Address is hexadecimal 0006) for the input in
question. Therefore, to read the 16 Bit Integer and 16 Bit Fraction for System Pressure the
following command is issued (the following data are presented in hexadecimal format):
Number of
Device Function Address Registers CRC
01 04 00 06 00 02 91 CA

Data
Device Function Byte Reg-1 Reg-2 CRC
Address Code Count Hi Lo Hi Lo Lo Hi
01 04 04 00 64 13 4E 37 5F
Register 1 is the Integer portion of the System Pressure or (0064h, 100 decimal). Register 2
is the Fraction portion of the System Pressure or (134Eh, 4942 decimal). Each fraction has
a range between 0 and 9999. So the System Pressure, expressed as a floating point
number is 100.4942 psi.
Example: Read Single Channel IEEE 32-Bit Floating Point Number
To continue with the example, when you decide to get the System Pressure as an IEEE 32
Bit floating point number you must issue the following command:
22204796 Rev. B, Version 3.10
Number of
01 04 0B BE 00 02 13 CB

Data
Device Function Byte Reg-1 Reg-2 CRC
Address Code Count Hi Lo Hi Lo Lo Hi
01 04 04 42 DC D4 C6 F1 54
So the System Pressure, expressed as a floating point number is 110.4155731201 psi.

IEEE floating-point numbers are represented in 32 bits as shown below.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
exponent mantissa
sign
Convert hexadecimal registers 1 and 2 (Reg-1, Reg-2) into decimal values ...
Register Byte Symbol Hex Decimal
1 Hi R1HB 42 66
1 Lo R1LB DC 220
2 Hi R2HB D4 212
2 Lo R2LB C6 198
Determine the sign (positive = 0 or negative = 1) ...

Sign = (R1HB And 128) / 128, where And is defined as a bit-wise And
Sign = (66 And 128) / 128 = 0
Determine the exponent ...
Exponent = ((R1HB And 127) ∗ 2) + INT(R1LB / 128), where INT is defined as INTEGER
Exponent = ((66 And 127) ∗ 2) + INT(220/128) = 133
Determine the mantissa...
Mantissa = ((((R1LB And 127) ∗ 256) + R2HB) ∗ 256) + R2LB
Mantissa = ((((220 And 127) ∗ 256) + 212) ∗ 256) + 198 = 6083782
Putting the 32 bit IEEE value together...
Value = (-1sign) ∗ (2(exponent - 127)) ∗ ((Mantissa ∗ 2-23) + 1)
Value = (-10) ∗ (2(133- 127)) ∗ ((6083782 ∗ 2-23) + 1) = 110.4155731201
NOTE
When Sign = Exponent = Mantissa = 0, Value = 0. This is a special case for the
above equation.
22204796 Rev. B, Version 3.10

Example: Read Multiple Channels

The procedure for reading multiple channels is the same as reading a single channel with
the exception of requesting more data. NOTE: You must read a contiguous group of
registers (channels) for a single command.
Function 05 - Force Single Coil

Forces a single coil (MODBUS 0x references) to either ON or OFF. When broadcast, the
function forces the same coil reference in all attached slaves. Refer to the table below for
MODBUS Absolute Addresses for each coil supported by the CMC-MODBUS Interface.
NOTE
The Force Single Coil command will override the CMC’s current state. The forced
state will remain valid until the CMC next solves the coil. The coil will remain forced if
it is not programmed in the CMC logic.
CAUTION
For all of the following Remote Coils, the compressor’s REMOTE

COMMUNICATIONS DISABLED/ENABLED selector switch must be in the ENABLED
position for these commands to execute. When DISABLED, the CMC ignores (there
is no exception response) these coils being forced ON or OFF.
Absolute Relative
Address Address Coil Name - Write Only
(decimal) (hex)
00221 00-DC Remote Horn Silence (Acknowledge)
00222 00-DD Remote Reset
00223 00-DE Remote Load
00224 00-DF Remote Unload
00225 00-E0 Remote Start
00226 00-E1 Remote Stop
Example: Forcing a Coil

For all MODBUS devices, a value of FF 00 hex requests the coil to be ON. A value of 00 00
requests it to be OFF. All other values are illegal and will not affect the coil. NOTE: For the
CMC, forcing the above listed coils OFF is not meaningful because the default state of each
of the above coils is OFF. When using these commands, they should be sent once
(momentary) and the CMC will execute the commands. To remotely reset the compressor,
the following command is issued:
Forced
Device Function Address Data CRC
01 05 00 DD FF 00 1C 00
22204796 Rev. B, Version 3.10

The response from this command is identical to the command sent:

Number of
01 05 00 DD FF 00 1C 00
Function 06 - Preset Single Register

Presets a value into a single holding register (MODBUS 4x reference). When broadcast, the
function presets the same register reference in all attached slaves. Refer to the table for the
Holding Register list for the MODBUS Absolute Addresses supported by the CMC-
MODBUS Interface.
NOTE
The Preset Single Register command will override the CMC’s current state. The
preset value will remain valid in the register until the CMC logic next solves the
register contents. The register's value will remain if it is not programmed in the
controller's logic.
CAUTION
This function can only set a single 16-bit holding register. Since the CMC
operates with 32-bit values, you must use Function 16 (10 Hex) - Preset Multiple
Registers for setting the 32-bit IEEE register values. Also, you may not set the 16-bit
fraction without its 16-bit integer. Therefore, you must use the Preset Multiple
Registers function to send this 32-bit pair. See the examples that follow for
Function 16.
CAUTION
The position of the REMOTE COMMUNICATIONS DISABLED/ENABLED

selector switch is NOT considered when forcing coils or writing registers to the CMC.
Reads and Writes are always enabled. Repeatedly writing a value to a register or
forcing a coil without regard to the position of the switch can effectively disable a local
write. Please use caution when writing registers or forcing coils. The REMOTE
COMMUNICATIONS DISABLED/ENABLED selector switch is typically located on the
front door of the Compressor’s Control Panel.
Example: Presetting a Single Register (16-bit) Integer

To change the integer value for the User Pressure Setpoint (absolute address 40269,
relative address 01-0C) to 100 (00-64 hex) psi, send the following command...
22204796 Rev. B, Version 3.10

Register
Device Function Address Value CRC
01 06 01 0C 00 64 49 DE
The response from this command is identical to the command sent:

Register
Device Function Address Value CRC
01 06 01 0C 00 64 49 DE
Function 15 (0F Hex) - Force Multiple Coils

Forces each coil (MODBUS 0x reference) in a series of contiguous coils to either ON or
OFF. When broadcast, the function forces the same coil references in all attached slaves
(CMC Base Control Modules). Refer to the table for the Coil list for the MODBUS Absolute
Addresses supported by the CMC-MODBUS Interface.
NOTE
The Force Multiple Coils command will override the CMC’s current state. The forced
it is not programmed in the controller's logic.
CAUTION

Example: Forcing Multiple Coils

To force a reset (absolute address 00222, relative address DD) and start (absolute address
00225, relative address E0) of the compressor the following command is sent...
Number of Number Coil
Device Function Address Coils of Data Data CRC
Address Code Hi Lo Hi Lo Bytes Lo Lo Hi
01 0F 00 DD 00 04 01 09 12 83
The number of contiguous coils is four (00225, 00224, 00223 and 00222). The number of
data bytes is one because we can set up to eight coils in a single byte. The coil data is nine
22204796 Rev. B, Version 3.10

because we want to set the first bit and fourth bit in the byte (0000-1001, the bytes are
numbered right to left). All bits not used are padded with zero.
The response from this command is similar to the command sent except that the number of
data bytes and the coil data themselves are not echoed:
Number of
01 0F 00 DD 00 04 C4 32
Function 16 (10 Hex) - Preset Multiple Registers

Presets values into a sequence of contiguous holding registers (MODBUS 4x references).
When broadcast, the function presets the same register references in all attached slaves
(CMC Base Control Modules). Refer to the table for the Input Register list for the MODBUS
Absolute Addresses supported by the CMC-MODBUS Interface.
NOTE
The Preset Multiple Registers command will override the CMC’s current state. The
forced state will remain valid until the CMC next solves the register. The register will
remain forced if it is not programmed in the controller's logic.
CAUTION

Example: Presetting Holding Registers for 32-bit Values

The difficulty in setting 32-bit values is determining the four data bytes for the number you
want to send. The process required is...
1. Determine the sign (positive = 0 or negative = 1). This is the first bit.
2. Divide the decimal value by 2 until the result is less than 2, but greater than 1. Count
the number of iterations required. Add 127 to the number of iterations. This result is the
exponent. Convert this result to binary. These are the next eight bits.
3. From the result obtained from step 2, subtract 1. Then, multiply this result by 2. If the
result is less than 1, then the value of the first mantissa bit is 0. Otherwise, the
mantissa bit is 1. If the result is greater than or equal to 1, then subtract 1 from the
result and proceed with step 3 until the result is 0 or you have gone through this
process 23 times.
22204796 Rev. B, Version 3.10

4. Combine all 32 bits from the steps above and convert this value to hexadecimal. These
32 bits are the 4 hexadecimal data bytes needed for the command.
As an example, we will start with the decimal value Iteration Decimal Result
of 105.4. 1 105.40000 / 2 = 52.700000
2 52.70000 / 2 = 26.350000
1. Since this is a positive number, the first bit is 0. 3 26.35000 / 2 = 13.175000
4 13.17500 / 2 = 6.587500
2. Determine the exponent bits by ... 5 6.58750 / 2 = 3.293750
6 3.29375 / 2 = 1.646875
It took us six iterations to get the result to a number
that is less than two and greater than or equal to one.
Now, we must add 127 for an exponent of 133. Iteration Decimal Operatio Result Bit
n
Converting this to binary, the next eight bits are 1 1.646875 -1*2= 1.29375 1
represented as 10000101. 2 1.29375 -1*2= 0.5875 0
3 0.5875 *2= 1.175 1
3. Determine the mantissa bits by 4 1.175 -1*2= 0.35 0
5 0.35 *2= 0.7 0
From the table at right, 0100101100110011001100 6 0.7 *2= 1.4 1
represent the next 23 bits. 7 1.4 -1*2= 0.8 0
8 0.8 *2= 1.6 1
4. Combining the bits in sign, exponent and then 9 1.6 -1*2= 1.2 1
mantissa order ... 10 1.2 -1*2= 0.4 0
11 0.4 *2= 0.8 0
0100-0010-1101-0010-1100-1100-1100-1100 12 0.8 *2= 1.6 1
13 1.6 -1*2= 1.2 1
This converts to 42-D2-CC-CC in hexadecimal. 14 1.2 -1*2= 0.4 0
15 0.4 *2= 0.8 0
To change the holding registers for user pressure 16 0.8 *2= 1.6 1
setpoint (for 32 bit IEEE floating point numbers the 17 1.6 -1*2= 1.2 1
absolute address is 43269, relative address 0C-C4) to 18 1.2 -1*2= 0.4 0
105.4, issue the following command... 19 0.4 *2= 0.8 0
20 0.8 *2= 1.6 1
21 1.6 -1*2= 1.2 1
22 1.2 -1*2= 0.4 0
23 0.4 *2= 0.8 0
Number of Number Data Bytes for Data Bytes for

Device Function Address Registers of Data Register #1 Register #2 CRC
Address Code Hi Lo Hi Lo Bytes Hi Lo Hi Lo Lo Hi
01 10 0C C4 00 02 04 42 D2 CC CC 4A 18
data bytes and the data bytes themselves are not echoed:
Number of
01 10 0C C4 00 02 03 65
NOTE
Sending 32 bit values are typically not necessary. Sending the data as a 16 bit
integer only or a 16 bit integer and 16 bit fraction will satisfy most requirements. Some
systems have 32 bit capability built directly into their products. We have provided this
feature for those systems.
22204796 Rev. B, Version 3.10

CAUTION

Example: Presetting a 16-bit Integer and 16-bit Fraction Holding Register

Change the integer and fraction value for the user pressure setpoint (absolute address
40269, relative address 01-0C) to 110.5 psi. The integer portion of the number 110 (00-6E
hex) is placed at address 40269 and the fraction 0.5 is converted to 5000 (13-88 hex) and
is placed at address 40270 (or the second data byte). To change the register, issue the
following command...
Number of Number Data Bytes for Data Bytes for
Device Function Address Registers of Data Register #1 Register #2 CRC
Address Code Hi Lo Hi Lo Bytes Hi Lo Hi Lo Lo Hi
01 10 01 0C 00 02 04 00 6E 13 88 92 E1
data bytes and the data bytes themselves are not echoed:
Number of
01 10 01 0C 00 02 80 37
Exception Responses
Except for broadcast messages, when a master device sends a query to a slave device it
expects a normal response, in all other cases a time out or exception response is returned.
The four possible responses to a the master's query are:
• If the slave device receives the query without a communication error, and can handle
the query normally, it returns a normal response.
• If the slave does not receive the query due to a communication error, no response is
returned. The master program will eventually process a time-out condition for the query.
• If the slave receives the query, but detects a communication error (parity, or CRC), no
response is returned. The master program will eventually process a time-out condition
for the query.
• If the slave receives the query without a communication error, but cannot handle it (for
example, if the request is to read a nonexistent coil or register), the slave will return an
exception response informing the master of the nature of the error.
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The exception response message has two fields that differentiate it from a normal
response:
Function Code Field

For a normal response, the UCM echoes the function code of the original query in the
function code field of the response. All function codes have their most significant bits set to
zero; therefore, the values are always below 80 hexadecimal. When an exception response
occurs, the UCM sets the most significant bit of the function code to 1. This makes the
function code value in an exception response exactly 80 hexadecimal higher than the value
would be for a normal response.
Most Significant Bit Least Significant Bit
7 6 5 4 3 2 1 0
1 0 0 0 0 0 0 0
With the function code's most significant bit set, the application program can recognize an
exception response and can examine the data field for the exception code.
Data Field
For a normal response, the UCM will return information in the data field (depending upon
the query message sent). For an exception response, the UCM returns an exception code
in the data field. This defines the UCM’s condition that caused the exception.
22204796 Rev. B, Version 3.10

Exception Codes Supported by the CMC Microcontroller
Code Name Meaning

01 Illegal Function The function code received in the query is not an allowable action for the slave. This exception code happens when:
(1) the function code is other than 1, 2, 3, 4, 5, 6, 15 or 16
(2) a message has the incorrect number of bytes for the function specified
02 Illegal Data Address The data address received in the query is not an allowable address for the slave. This exception code happens when:
(1) the address is not programmed into the Base Control Module (BCM)
(2) the address is outside of the ranges
(a) 00001-00512 for coils
(b) 10001-10512 for discrete inputs
(c) 30001-31024 for integer and fractional analog inputs
(d) 33001-34024 for floating point analog inputs
(e) 40001-41024 for integer and fractional input registers
(f) 43001-44024 for floating point analog input registers
03 Illegal Data Value A value contained in the query data field is not an allowable value for the slave. This exception code happens when:
(1) the number of coils, discrete inputs, registers or analog inputs is equal to zero
(2) request for more than the maximum number of parameters
(3) the force single coil command, Function 05, is issued and the value is other than FF00 or 0000
(4) the force multiple coil command, Function 15, is issued and the number of bytes does not equal the number of bits
to set
(5) the preset single register command, Function 6, and preset multiple registers commands, Function 16, is issued
and the starting address is not even, the number of registers specified does not correspond to the number of bytes in
the message, the integer part of the number is outside the range –32768 to +32767, the fractional part of the number
is outside of the range 0-9999, or the value is not a valid 32 bit IEEE floating point number
04 Slave Device Failure An unrecoverable error occurred while the slave was attempting to perform the requested action. This exception code
happens when:
(1) no response from the Base Control Module (BCM) since 800 milliseconds from the time the message was sent …
BCM not wired properly, BCM hardware problem or BCM Module ID not equal to one
(2) when there is an unexpected response from the BCM … this is the default exception response
Maximum Query / Response Parameters

The listing below shows the maximum amount of data that the CMC Microcontroller can
return in a single slave response from a valid MODBUS command.
Function Maximum
Dec Hex Description Parameters
01 01 Read Coil Status 512 coils
02 02 Read Input Status 512 inputs
03 03 Read Holding Registers 64 registers
04 04 Read Input Registers 64 registers
05 05 Force Single Coil 1 coil
06 06 Preset Single Register 1 register
15 0F Force Multiple Coils 512 coils
16 10 Preset Multiple Registers 64 registers
CMC Data
The CMC Microcontroller supports several data types. They are coil, integer, fraction and
floating point.
• Coil - 1 bit, 1 means True or Active, 0 means False or Not Active.
• Integer - 16 bit signed integer, –32768 to +32767.
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• Fraction - 16 bit unsigned integer, 0 – 9999, represents the decimal (fractional) part of
the number (1 represents 0.0001, 10 represents 0.0010, 100 represents 0.0100 and
1000 represents 0.1000).
• Floating Point - 32 bit IEEE number (requires reading two registers to get full number).
For example if the System Pressure input is located on Channel 3 (address 30007) and the
value of the pressure is 100.5 then:
Address 30007 contains 100
Address 30008 contains 5000
Address 33007 contains the high 16 bits of the IEEE value for 100.5
Address 33008 contains the low 16 bits of IEEE value for 100.5
Additionally, the type of data in a location determines the commands that can be used to
access the data. For the previous example of System Pressure addresses 00007, 03007,
10007, 13007, 40007 and 43023 return errors because coil, input status and holding
register commands cannot read input register data.
Scaling and Units of Measure

The MODBUS data are scaled in English engineering units. All pressures are in psi,
temperatures in degrees F, vibrations in mils, and current in amps. For example, when the
CMC Operator User Interface displays the system pressure as 7.73 kg/cm2, the value for
system pressure obtained through MODBUS communications is 110 psi.
Communication Parameters
Configuration of the communication speed (baud rate), parity, number of data bits and
number of stop bits is available through the Ingersoll-Rand Service Tool and will be
provided by a certified Ingersoll-Rand Service Representative.
22204796 Rev. B, Version 3.10

The CMC-DF1 Interface

Introduction
Customers may want to communicate to the CMC control systems for remote compressor
control and monitoring through their Allen-Bradley data highway plus (DH+) network.
Adding Allen-Bradley DF1 protocol to the UCM module allows our customers to incorporate
our compressors into their plant-wide Allen-Bradley PLC control system. This
communication capability also provides for flexibility in the customer's compressed air
operation through remote start, stop, and data gathering for preventative maintenance.
The customer or his representative must write system software to suit his individual needs
for remote control and monitoring. Since the customer writes this interface, the system can
be as flexible as the customer desires.
One avenue for communicating with the CMC is via DF1 protocol over a full duplex RS-422
link. This requires an Allen-Bradley interface module 1770-KF2 to link our intelligent RS-
422A asynchronous device, Universal Communication Module (UCM), to the Allen-Bradley
DH+ network.
The CMC Microcontroller can communicate with other devices over a variety of
communication standards. Supported standards, or protocols, include RS-232, IRBUS
(Ingersoll-Rand Proprietary), Modicon’s MODBUS, and Allen-Bradley DF1. The built-in
ports of the CMC’s Universal Communication Module access communications. This UCM-
DF1 Interface defines the message structure that a CMC Microcontroller uses to exist on a
DH+ network. This interface will allow the DH+ network to gather information and control
the compressor.
The information presented in these sections that follow do not include the Allen-Bradley
DF1 protocol details. Detailed information can be obtained from “Allen-Bradley Publication
1770-6.5.117 - October 1996” - DF1 Protocol and Command Set Reference Manual and
“Data Highway or Data Highway Plus Asynchronous (RS-232-C or RS-422-A) Interface
Module (Cat. No. 1770-KF2) User’s Manual”.
A DH+ link implements peer-to-peer communication with a token-passing scheme to rotate
mastership among the nodes connected to that link. In order to communicate over Allen-
Bradley DH+ network, an Allen-Bradley 1770-KF2 interface module must be used. The
1770-KF2 always acts as one node on the DH+ network, which translates DH+ messages
to DF1 format, and passes these messages on to the UCM on the RS-422A asynchronous
end, or vice versa.
The following is a picture of 1770-KF2:
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Full-Duplex Protocol
The UCM-DF1 interface only supports the point-to-point full-duplex DF1 protocol, which is
like a two-lane bridge; traffic can travel in both directions at one time. Full-duplex protocol
also provides higher performance applications to get the highest possible throughput.
DF1 Full-Duplex Protocol Message Frames

The following table shows the general format of a DF1 full-duplex message frame. The
control symbols DLE STX bytes are sender symbols indicating the start of a message
frame. The control symbols DLE ETX BCC (CRC) bytes are sender symbols that terminates
a message frame. The bytes comprised in the command data field vary from command to
command.
DLE STX DST SRC CMD STS TNS Command Data DLE ETX BCC(CRC)
NOTE
The standard definitions of the control characters used by DF1 full-duplex protocol
are listed below:
Abbreviation Hexadecimal Value

STX 02
ETX 03
ENQ 05
ACK 06
DLE 10
NAK 0F
DF1 Device Address

Configuration of the DF1 device address is available through the Ingersoll-Rand UCM-
Wizard Tool and will be configured by a certified Ingersoll-Rand Service Representative.
CAUTION
The UCM must be configured to have the same node address as 1770-KF2
interface module. Otherwise, the DF1 messages will not be relayed to the IRBUS port
of the UCM.
Destination (DST) Byte

This byte indicates the destination node address for the message. For a command
message, it will be the address of the 1770-KF2 module. The UCM must have the same
address as the 1770-KF2, which can be configured using the Ingersoll-Rand UCM-wizard
software.
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Source (SRC) Byte

This byte indicates the source node address of the message. If the command is initiated
from an Allen-Bradley PLC, the SRC byte will be the address of the processor module.
Command (CMD) and Function (FNC) Bytes

The CMD byte defines the command type. The FNC byte defines the specific function
under that command type. These bytes together define the activity being performed by the
command message at the destination node. The message format depends on the CMD and
FNC values.
CMD Byte
Bit: 7 6 5 4 3 2 1 0
0 0:Command msg 0: normal priority(for DH+) 0 Command code
1:Reply msg 1: high priority(only applies to DH link)
From the figure above, the CMD byte of a reply message for DH+ network is always 40h
ORed with the CMD byte of its original command message.
Status (STS) Byte - Status Error Code

Bit: 7 6 5 4 3 2 1 0
Remote Error Nibble Local Error Nibble
Bits 7, 6, 5, and 4 are used to report remote errors - errors that occur when the command
executor at the destination node tries to execute the command message. Bits 3, 2, 1, and 0
are used to report local errors - errors found by the local source node and code 09h through
0Fh are not used. The UCM-DF1 driver uses mainly the higher nibble to report errors occur
in CMC. A special error code with non-zero local error nibble, 3Fh, is used to report errors
caused by illegal CMC data table address or count. The maximum number of data table
entries allowed to be read or set for CMC is 16 currently. If a read command requests more
than 16 data items from CMC, an exception response of 3Fh will be returned.
Following is a list of status error code supported by the UCM-DF1 driver:
Transaction (TNS) Bytes

The two TNS bytes contain a unique 16-bit transaction identifier. Generate this number by
maintaining a 16-bit counter. Increment the counter each time your command initiator
creates a new message, and store the counter value in the two TNS bytes of the new
message. You must use only one TNS counter in a multi-tasking environment.
If the command initiator is an Allen-Bradley PLC, the PLC will maintain the counter
internally. The reply message should have the same TNS value as the original command
message. The UCM-DF1 driver copies the original TNS field of the command message into
the TNS field of the corresponding reply message.
BCC (Block Check Character) and CRC (Cyclic Redundancy Check)

At the end of each DF1 command message, there is a one-byte BCC field, or a two-byte
CRC field for error checking. These bytes allow you to verify the accuracy of each message
frame transmission. SW-1 of 1770-KF2 module allows you to select BCC or CRC error
checking for the command messages sent to CMC. The Ingersoll-Rand UCM-wizard
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software allows you to configure BCC or CRC error checking for the UCM-DF1 driver,
which needs to be the same error checking method as 1770-KF2.
BCC (One Byte)
The BCC field contains the 2’s compliment of the 8-bit sum of all data bytes between DLE
STX and DLE ETX BCC control characters. BCC provides a medium level of data security.
It cannot detect either the transposition of bytes during transmission nor the insertion or
deletion of the value zero within a message frame.
Another way to quickly determine a BCC value, add up the hex values of all data bytes
between DLE STX and DLE ETX BCC in the message frame. If the total is greater than
100h, drop the most significant digit, and then subtract the result from 100h. This gives you
the BCC.
CRC (Two Bytes)
This provides a higher level of data security than BCC but is more difficult to implement. All
the data bytes between DLE STX and DLE ETX CRC plus the ETX byte are used to
calculate the CRC value.
The following explains how to calculate the CRC value:
• Before starting the calculation, a 16-bit register used to store the CRC value is cleared
to be zero.
• As a byte is fetched from the data buffer, it is XORed (least-significant bit to the right)
with the right eight bits of the CRC register.
• The result is placed in the right eight bits of the CRC register.
• Inserting 0s on the left then shifts the 16-bit CRC Register right eight times. Each time a
1 is shifted out on the right, the CRC register is XORed with a 16-bit constant A0-01h.
• As each additional byte is fetched, it is included in the value in the register the same
way.
• After the ETX byte transmitted is also included in the calculation, the CRC calculation is
complete. The 16-bit CRC value is transmitted low byte first then high byte.
Comparing the calculated BCC/CRC bytes with the received BCC/CRC bytes always
validates the DF1 messages received by UCM.
CAUTION
To transmit the data value of 10 hex, you must use the data symbol DLE DLE
(double-stuffing DLEs). However, only one of these DLE bytes is included in the
BCC/CRC calculation. However, if your BCC check sum is 10 hex, send it as DLE
and not DLE DLE.
The rest of this section explains the meaning of the data bytes between DLE STX and DLE
ETX BCC/CRC control characters.
Usually, a command message stripping off the control characters has the following format,
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DST SRC CMD STS TNS command specific data packet
a reply message to a read command has the format below,

SRC DST CMD STS TNS command specific data packet
a reply message to a write command has the following format,

SRC DST CMD STS TNS
The DST and SRC bytes of a reply message are formed by interchanging the DST and
SRC bytes of the corresponding command message. The combination of SRC, CMD, and
TNS bytes uniquely identifies every message packet. If all fields are the same, the message
is considered to be a duplicate. The UCM-DF1 driver does not detect duplicate messages.
Scaling and Units of Measure

The MODBUS data are scaled in English engineering units. All pressures are in psi,
temperatures in degrees F, vibrations in mils, and current in amps. For example, when the
CMC Operator User Interface displays the system pressure as 7.73 kg/cm2, the value for
system pressure obtained through MODBUS communications is 110 psi.
Data Addressing
The CMC is primarily a 32-bit floating-point microprocessor controller. We support two
methods for determining the analog data value. These methods are two 16-bit integers
representing the integer and fraction part of the number and one 32-bit IEEE floating point
number. (NOTE: If you use the 16-bit system, you must get two 16-bit numbers and
combine them into one 32-bit floating point number.) The UCM-DF1 interface can prepare
data as either two 16-bit integers or one 32-bit floating point number with respect to the
received DF1 command. The Allen-Bradley PLC floating point format is a subset of IEEE
STD 754-1985.
Accessing data from the CMC via DF1 interface emulates accessing data from a PLC5 or
SLC5/04. In SLC 5/04, each data file can hold up to 256 data elements (element number: 0-
255) and the file number has to be in the same range (0-255). The UCM-DF1 addressing
scheme uses this file/element structure and complies with the SLC5/04’s limits on file
number and element number. Please see next section for details.
A DF1 command initiator is a device on the DH+ network that initiates the query or set
commands to the CMC. It can be an Allen-Bradley PLC or other device that can
send/receive a PLC5 Typed Read (Write) or SLC Typed Logical Read (Write)
command/response.
CMC as PLC5
As to treating CMC as a PLC5, the command initiator can issue a PLC5 Typed Read
(Write) command to the CMC. Please see the section on Supported Functions for detailed
message format.
For a PLC5 Typed Write command, the data can be sent as either two 16-bit integers or
one 32-bit floating point. If a PLC5 or SLC5/04 issues the command, the setpoint data type
is determined by the local data file type used to store it.
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The PLC5 Typed Read commands for requesting data in integer or float format is exactly
the same messages. The UCM-DF1 driver cannot tell the requested data type from the
command bytes received. Therefore, the returned data type has to be pre-configured in
UCM via the Ingersoll-Rand UCM-wizard tool. Default is the integer type. If a PLC5 or
SLC5/04 issues the command, the local data file used to store the gathered data should be
the same type. Otherwise, you get erroneous data or an error status code due to data type
mismatch.
CMC as SLC5/04
As to treating a CMC as a SLC5/04, the command initiator can issue a SLC Typed Logical
Read (Write) command to the CMC. Please see the section on Supported Functions for
detailed message format.
If the command initiator is another SLC5/04, you can do either integer or float data type.
However, if the command initiator is a PLC5, only integer type is supported for the time
being.
Data File Addressing for PLC5/SLC504

When RSLogix software is used to program message instructions in PLC for sending
read/write commands to the CMC, the target data table address is in the form of either
Fxx:yyy or Nxx:yyy, where xx is the file number (10-14) and yyy (0-255) is the
corresponding CMC data table address. The target file type (F for float, N for integer)
should be consistent with the local file type.
NOTE
File numbers 10-14 are reserved for address only!
The UCM-DF1 interface designates file number 10 for discrete usage (READ ONLY). Each
element represents 16 Boolean data bit-packed together in two bytes. File type can be
either N (integer) or B (bit) type. The following table shows the address in file 10 for discrete
values.
PLC CMC Data Table 16 Discretes
File Address Packed as Binary Bits in Two Bytes
Address (decimal) 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
B10:10 160-175 175 174 173 172 171 170 169 168 167 166 165 164 163 162 161 160
B10:11 176-191 191 190 189 188 187 186 185 184 183 182 181 180 179 178 177 176
B10:12 192-207 207 206 205 204 203 202 201 200 199 198 197 196 195 194 193 192
B10:13 208-223 223 222 221 220 219 218 217 216 215 214 213 212 211 210 209 208
Bit 10-15 of integer element 10 in data file 10 represents digital input channels 1-6 (CMC
data table address 170-175). Bit 0-9 of integer element 11 represent digital input channels
7-16 (CMC data table address 176-185). Bit 10-15 of integer element 11 represents digital
output channels 1-6 (CMC data table address 186-191). Bit 0-9 of integer element 12
represent digital output channels 7-16 (CMC data table address 192-201). Bit 10-15 of
integer element 11 represents digital output channels 1-6 (CMC data table address 186-
191). Bit 10-15 of integer element 12 and bit 0-10 of integer element 13 represent various
compressor states (CMC data table address 202-218).
Currently, CMC data table has 512 entries. In order to satisfy the (0-255) limit of elements
per data file for SLC5/04, the CMC data table is divided into two segments; each has 256
22204796 Rev. B, Version 3.10
entries. File number 11 is designated to the first 256 entries. File number 12 is for the
second 256 entries. If the CMC data table gets expanded later, the subsequent file number
will be used.
According to the above, N11:170 refers to the 170-th item in the CMC data table, which is
the digital input channel 1. Similarly, N12:170 will be the 426-th = (170+256) item in the
CMC data table. If an invalid file or element number is used, you will get a 3Fh-status error
code. See the status error code section for details.
The number of bytes per element is 2 for integer type and 4 for float type. The assigned
message length in elements for local data file should be a multiple of 2 for integer type. If it
is an odd number, only the 2-byte integer (whole) part will be transmitted for the last data
item.
Since the CMC has programmable analog and discrete inputs and outputs, the programmer
must use the electrical schematic supplied with the machine to determine which function
name and units of measure are associated with each input and output.
22204796 Rev. B, Version 3.10

CMC Data Addressing

Refer to the table below for data addresses supported by the UCM-DF1 Interface.
Data Data Data Data
Address Address Description Address Address Description
1 01 Analog Input, Ch 1 (J2-P1,3) 42 2A Analog Input, Ch 4 (J1-P4) – Hi Trip Setpoint
2 02 Analog Input, Ch 2 (J2-P5,7) 43 2B Analog Input, Ch 4 (J1-P4) – Hi Alarm Setpoint
3 03 Analog Input, Ch 3 (J1-P1) 44 2C Analog Input, Ch 4 (J1-P4) - Lo Alarm Setpoint
4 04 Analog Input, Ch 4 (J1-P4) 45 2D Analog Input, Ch 4 (J1-P4) - Lo Trip Setpoint
5 05 Analog Input, Ch 5 (J1-P5) 46 2E Analog Input, Ch 5 (J1-P5) - Hi Trip Setpoint
6 06 Analog Input, Ch 6 (J1-P8) 47 2F Analog Input, Ch 5 (J1-P5) - Hi Alarm Setpoint
7 07 Analog Input, Ch 7 (J1-P9) 48 30 Analog Input, Ch 5 (J1-P5) - Lo Alarm Setpoint
8 08 Analog Input, Ch 8 (J1-P12) 49 31 Analog Input, Ch 5 (J1-P5) - Lo Trip Setpoint
9 09 Analog Input, Ch 9 (J1-P13) 50 32 Analog Input, Ch 6 (J1-P8) - Hi Trip Setpoint
10 0A Analog Input, Ch 10 (J1-P16) 51 33 Analog Input, Ch 6 (J1-P8) - Hi Alarm Setpoint
11 0B Analog Input, Ch 11 (J1-P17) 52 34 Analog Input, Ch 6 (J1-P8) - Lo Alarm Setpoint
12 0C Analog Input, Ch 12 (J1-P20) 53 35 Analog Input, Ch 6 (J1-P8) - Lo Trip Setpoint
13 0D Analog Input, Ch 13 (J1-P21) 54 36 Analog Input, Ch 7 (J1-P9) - Hi Trip Setpoint
14 0E Analog Input, Ch 14 (J1-P24) 55 37 Analog Input, Ch 7 (J1-P9) - Hi Alarm Setpoint
15 0F Analog Input, Ch 15 (J1-P25) 56 38 Analog Input, Ch 7 (J1-P9) - Lo Alarm Setpoint
16 10 Analog Input, Ch 16 (J1-P28) 57 39 Analog Input, Ch 7 (J1-P9) - Lo Trip Setpoint
17 11 Analog Input, Ch 17 (J1-P29) 58 3A Analog Input, Ch 8 (J1-P12) - Hi Trip Setpoint
18 12 Analog Input, Ch 18 (J1-P32) 59 3B Analog Input, Ch 8 (J1-P12) - Hi Alarm Setpoint
19 13 Analog Input, Ch 19 (J1-P33) 60 3C Analog Input, Ch 8 (J1-P12) - Lo Alarm Setpoint
20 14 Analog Input, Ch 20 (J1-P36) 61 3D Analog Input, Ch 8 (J1-P12) - Lo Trip Setpoint
21 15 Analog Input, Ch 21 (J1-P37) 62 3E Analog Input, Ch 9 (J1-P13) - Hi Trip Setpoint
22 16 Analog Input, Ch 22 (J1-P40) 63 3F Analog Input, Ch 9 (J1-P13) - Hi Alarm Setpoint
23 17 Analog Input, Ch 23 (J1-P41) 64 40 Analog Input, Ch 9 (J1-P13) - Lo Alarm Setpoint
24 18 CT Input (J9-P1,2) 65 41 Analog Input, Ch 9 (J1-P13) - Lo Trip Setpoint
25 19 Reserved 66 42 Analog Input, Ch 10 (J1-P16) - Hi Trip Setpoint
26 1A Analog Output, Ch 1 (J3-P1,3) 67 43 Analog Input, Ch 10 (J1-P16) - Hi Alarm Setpoint
27 1B Analog Output, Ch 2 (J3-P4,6) 68 44 Analog Input, Ch 10 (J1-P16) - Lo Alarm Setpoint
28 1C Analog Output, Ch 3 (J3-P7,9) 69 45 Analog Input, Ch 10 (J1-P16) - Lo Trip Setpoint
29 1D Analog Output, Ch 4 (J3-P10,12) 70 46 Analog Input, Ch 11 (J1-P17) - Hi Trip Setpoint
30 1E Analog Input, Ch 1 (J2-P1,3) – Hi Trip Setpoint 71 47 Analog Input, Ch 11 (J1-P17) - Hi Alarm Setpoint
31 1F Analog Input, Ch 1 (J2-P1,3) – Hi Alarm Setpoint 72 48 Analog Input, Ch 11 (J1-P17) - Lo Alarm Setpoint
32 20 Analog Input, Ch 1 (J2-P1,3) – Lo Alarm Setpoint 73 49 Analog Input, Ch 11 (J1-P17) - Lo Trip Setpoint
33 21 Analog Input, Ch 1 (J2-P1,3) – Lo Trip Setpoint 74 4A Analog Input, Ch 12 (J1-P20) - Hi Trip Setpoint
34 22 Analog Input, Ch 2 (J2-P5,7) – Hi Trip Setpoint 75 4B Analog Input, Ch 12 (J1-P20) - Hi Alarm Setpoint
35 23 Analog Input, Ch 2 (J2-P5,7) – Hi Alarm Setpoint 76 4C Analog Input, Ch 12 (J1-P20) - Lo Alarm Setpoint
36 24 Analog Input, Ch 2 (J2-P5,7) – Lo Alarm Setpoint 77 4D Analog Input, Ch 12 (J1-P20) - Lo Trip Setpoint
37 25 Analog Input, Ch 2 (J2-P5,7) – Lo Trip Setpoint 78 4E Analog Input, Ch 13 (J1-P21) - Hi Trip Setpoint
38 26 Analog Input, Ch 3 (J1-P1) – Hi Trip Setpoint 79 4F Analog Input, Ch 13 (J1-P21) - Hi Alarm Setpoint
39 27 Analog Input, Ch 3 (J1-P1) – Hi Alarm Setpoint 80 50 Analog Input, Ch 13 (J1-P21) - Lo Alarm Setpoint
40 28 Analog Input, Ch 3 (J1-P1) – Lo Alarm Setpoint 81 51 Analog Input, Ch 13 (J1-P21) - Lo Trip Setpoint
41 29 Analog Input, Ch 3 (J1-P1) – Lo Trip Setpoint 82 52 Analog Input, Ch 14 (J1-P24) - Hi Trip Setpoint
22204796 Rev. B, Version 3.10

Data Data Data Data

83 53 Analog Input, Ch 14 (J1-P24) - Hi Alarm Setpoint 142 8E Start Timer
84 54 Analog Input, Ch 14 (J1-P24) - Lo Alarm Setpoint 143 8F CT Ratio
85 55 Analog Input, Ch 14 (J1-P24) - Lo Trip Setpoint 144 90 Reserved
86 56 Analog Input, Ch 15 (J1-P25) - Hi Trip Setpoint 145 91 Reserved
87 57 Analog Input, Ch 15 (J1-P25) - Hi Alarm Setpoint 146 92 Reserved
88 58 Analog Input, Ch 15 (J1-P25) - Lo Alarm Setpoint 147 93 Reserved
89 59 Analog Input, Ch 15 (J1-P25) - Lo Trip Setpoint 148 94 Power on hours
90 5A Analog Input, Ch 16 (J1-P28) - Hi Trip Setpoint 149 95 Running Hours
91 5B Analog Input, Ch 16 (J1-P28) - Hi Alarm Setpoint 150 96 Loaded Hours
92 5C Analog Input, Ch 16 (J1-P28) - Lo Alarm Setpoint 151 97 Number of starts
93 5D Analog Input, Ch 16 (J1-P28) - Lo Trip Setpoint 152 98 Reserved
94 5E Analog Input, Ch 17 (J1-P29) - Hi Trip Setpoint 153 99 Reserved
95 5F Analog Input, Ch 17 (J1-P29) - Hi Alarm Setpoint 154 9A Reserved
96 60 Analog Input, Ch 17 (J1-P29) - Lo Alarm Setpoint 155 9B Reserved
97 61 Analog Input, Ch 17 (J1-P29) - Lo Trip Setpoint 156 9C Reserved
98 62 Analog Input, Ch 18 (J1-P32) - Hi Trip Setpoint 157 9D Reserved
99 63 Analog Input, Ch 18 (J1-P32) - Hi Alarm Setpoint 158 9E Reserved
100 64 Analog Input, Ch 18 (J1-P32) - Lo Alarm Setpoint 159 9F Reserved
101 65 Analog Input, Ch 18 (J1-P32) - Lo Trip Setpoint 160 A0 Reserved
102 66 Analog Input, Ch 19 (J1-P33) - Hi Trip Setpoint 161 A1 Reserved
103 67 Analog Input, Ch 19 (J1-P33) - Hi Alarm Setpoint 162 A2 Inlet Valve Proportional Constant
104 68 Analog Input, Ch 19 (J1-P33) - Lo Alarm Setpoint 163 A3 Inlet Valve Integral Constant
105 69 Analog Input, Ch 19 (J1-P33) - Lo Trip Setpoint 164 A4 Reserved
106 6A Analog Input, Ch 20 (J1-P36) - Hi Trip Setpoint 165 A5 Bypass Valve Proportional Constant
107 6B Analog Input, Ch 20 (J1-P36) - Hi Alarm Setpoint 166 A6 Bypass Valve Integral Constant
108 6C Analog Input, Ch 20 (J1-P36) - Lo Alarm Setpoint 167 A7 Reserved
109 6D Analog Input, Ch 20 (J1-P36) - Lo Trip Setpoint 168 A8 Reserved
110 6E Analog Input, Ch 21 (J1-P37) - Hi Trip Setpoint 169 A9 Compressor Control Mode
111 6F Analog Input, Ch 21 (J1-P37) - Hi Alarm Setpoint 170 AA Digital Input, Ch 1 (J4-P2)
112 70 Analog Input, Ch 21 (J1-P37) - Lo Alarm Setpoint 171 AB Digital Input, Ch 2 (J4-P3)
113 71 Analog Input, Ch 21 (J1-P37) - Lo Trip Setpoint 172 AC Digital Input, Ch 3 (J4-P4)
114 72 Analog Input, Ch 22 (J1-P40) - Hi Trip Setpoint 173 AD Digital Input, Ch 4 (J4-P5)
115 73 Analog Input, Ch 22 (J1-P40) - Hi Alarm Setpoint 174 AE Digital Input, Ch 5 (J4-P6)
116 74 Analog Input, Ch 22 (J1-P40) - Lo Alarm Setpoint 175 AF Digital Input, Ch 6 (J4-P7)
117 75 Analog Input, Ch 22 (J1-P40) - Lo Trip Setpoint 176 B0 Digital Input, Ch 7 (J4-P8)
118 76 Analog Input, Ch 23 (J1-P41) - Hi Trip Setpoint 177 B1 Digital Input, Ch 8 (J4-P9)
119 77 Analog Input, Ch 23 (J1-P41) - Hi Alarm Setpoint 178 B2 Digital Input, Ch 9 (J5-P2)
120 78 Analog Input, Ch 23 (J1-P41) - Lo Alarm Setpoint 179 B3 Digital Input, Ch 10 (J5-P3)
121 79 Analog Input, Ch 23 (J1-P41) - Lo Trip Setpoint 180 B4 Digital Input, Ch 11 (J5-P4)
122 7A Reserved 181 B5 Digital Input, Ch 12 (J5-P5)
123 7B Reserved 182 B6 Digital Input, Ch 13 (J5-P6)
124 7C Reserved 183 B7 Digital Input, Ch 14 (J5-P7)
125 7D Reserved 184 B8 Digital Input, Ch 15 (J5-P8)
126 7E Reserved 185 B9 Digital Input, Ch 16 (J5-P9)
127 7F Reserved 186 BA Digital Output, Ch 1 (J15-P7,8)
128 80 Reserved 187 BB Digital Output, Ch 2 (J15-P5,6)
129 81 Reserved 188 BC Digital Output, Ch 3 (J15-P3,4)
130 82 Reserved 189 BD Digital Output, Ch 4 (J15-P1,2)
131 83 Surge Pressure Rate 190 BE Digital Output, Ch 5 (J14-P7,8)
132 84 Surge Current Rate 191 BF Digital Output, Ch 6 (J14-P5,6)
133 85 Motor Current 192 C0 Digital Output, Ch 7 (J14-P3,4)
134 86 User Pressure Setpoint 193 C1 Digital Output, Ch 8 (J14-P1,2)
135 87 MinLoad (Throttle Limit, TL) 194 C2 Digital Output, Ch 9 (J13-P7,8)
136 88 MaxLoad (High Load Limit, HLL) 195 C3 Digital Output, Ch 10 (J13-P5,6)
137 89 Autodual Reload Percent 196 C4 Digital Output, Ch 11 (J13-P3,4)
138 8A Autodual Unload Point 197 C5 Digital Output, Ch 12 (J13-P1,2)
139 8B Autodual Unload Timer 198 C6 Digital Output, Ch 13 (J12-P7,8)
140 8C Pressure Setpoint Ramp Rate 199 C7 Digital Output, Ch 14 (J12-P5,6)
141 8D Inlet Valve Unload Position 200 C8 Digital Output, Ch 15 (J12-P3,4)
22204796 Rev. B, Version 3.10

Data Data Data Data

201 C9 Digital Output, Ch 16 (J12-P1,2) 213 D5 Compressor State - Loading
202 CA Compressor State - Waiting 214 D6 Compressor State - Loaded
203 CB Compressor State - Coasting 215 D7 Compressor State - Full Load
204 CC Compressor State – Starting 216 D8 Compressor State - Analog Input Failed
205 CD Compressor State - Not Ready 217 D9 Any Compressor Trip
206 CE Compressor State - Ready 218 DA Any Compressor Alarm
207 CF Compressor State - Surge Unload 220 DC Remote Acknowledge
208 D0 Compressor State - Autodual Unload 221 DD Remote Reset
209 D1 Compressor State - Unloading 222 DE Remote Load
210 D2 Compressor State - Unloaded 223 DF Remote Unload
211 D3 Compressor State - Min load 224 E0 Remote Start
212 D4 Compressor State - Max load 225 E1 Remote Stop
Supported Functions
The listing below shows the DF1 commands supported by the CMC Microcontroller.
Command Function
Code Code Function Name
(hex) (hex)
0F 68 PLC5 Typed Read
0F 67 PLC5 Typed Write
0F A2 SLC Typed Logical Read
0F AA SLC Typed Logical Write
Command 0F/Function 68 - PLC5 Typed Read

The CMC is treated as a PLC5 when this command is issued. This command reads a block
of data from CMC starting at a specified data table address.
As to the format of floating point number, Allen-Bradley DF1 protocol always put low byte
first then high byte, low word first then high word, which is different from the UCM-
MODBUS protocol. The byte format for a floating point value, 105.4, is differentiated
between the two interfaces as below (Byte 1 to 4 is in the order of transmission):
Floating Point Byte Representation
Protocol Byte 1 Byte 2 Byte 3 Byte 4
UCM-MODBUS 42 D2 CC CD
UCM-DF1 CD CC D2 42
Example: Reading an Analog Input

After reviewing the Electrical Schematic for your compressor, you determine that the analog
input for system pressure is located on J1-P1 (Channel 3). From the CMC data table above,
the address is 03h. The UCM should be configured to represent data type as desired.
Following is a table illustrating how the PLC5 system address is mapped to the CMC data
table address.
22204796 Rev. B, Version 3.10

CMC PLC5 PLC5 System Address

Data Target Data Element
Address Table Address File Number
3 N11:3 07 00 0B 03
254 N11:254 07 00 0B FE
255 N11:255 07 00 0B FF FF 00
256 N12:0 07 00 0C 00
259 N12:3 07 00 0C 03
As 16-Bit Integer and Fraction

To get the reading of system pressure as 16-bit integer and 16-bit fraction, the following
command is issued (data are presented in hexadecimal format):
DLE STX DST SRC CMD STS TNS FNC Packet Total PLC5 System Address Size DLE ETX BCC
Offset Trans
10 02 0D 11 0F 00 21 BD 68 00 00 02 00 07 00 0B 03 02 00 10 03 74

DLE STX DST SRC CMD STS TNS A B DLE ETX BCC
10 02 11 0D 4F 00 21 BD 99 09 05 42 64 00 5C 09 10 03 03
In the response above, the first two bytes (low byte first then high byte) in field B is the
integer portion of the system pressure (00-64h, 100 decimal). The second two bytes in field
B are the fraction portion of the system pressure (09-5Ch, 2396 decimal). Each fraction has
a range between 0 and 9999. So the system pressure, expressed as a floating-point
number, is 100.2396 PSIG.
The following table contains a list of data types and the ID value of each supported by
Allen-Bradley DF1 protocol:
Data Type ID Data Type
1 bit
2 bit string
3 byte (or character) string
4 integer
5 Allen-Bradley timer
6 Allen-Bradley counter
7 Allen-Bradley general control structure
8 IEEE floating point
9 array of similar elements
15 address data
16 binary-coded decimal (BCD)
The first byte, 99h, in field A of the above response message is a flag byte, which has the
format below:
Data Type ID Data Type Size
Bit: 7 6 5 4 3 2 1 0
1 0 0 1 1 0 0 1
If the data type ID is greater than 7, set bit 7 of this flag byte to 1 and insert the number of
bytes to follow that contains the data type ID value in bits 4, 5, and 6. These additional ID
bytes follow directly after the flag byte. In the above response message, the additional one
byte is 09h, which means array of similar elements.
22204796 Rev. B, Version 3.10

If the data type defined uses more than 7 bytes for each data element, enter 1 in bit 3 of the
flag byte and enter the number of bytes to follow that contains the number of bytes used for
each data element. These additional size bytes follow the flag byte and any ID bytes.
The individual bytes in field A and B of the above response message is explained in the
following table:
Field Byte (hex) Definition
99 flag byte
09 data type ID byte: array of similar elements
A 05 number of bytes to follow
42 descriptor byte
4: type ID for integer
2: two bytes per element
64
B 00 4 data bytes
5C
09
As IEEE 32-Bit Floating Point Number

If the UCM is configured to read data as floating point, the following command is sent:
Offset Trans
10 02 0D 11 0F 00 21 BD 68 00 00 01 00 07 00 0B 03 01 00 10 03

10 02 11 0D 4F 00 21 BD 99 09 06 94 08 C6 D4 DC 42 10 03
The individual bytes in field A and B of the above response message is explained in the
table below:
Field Byte (hex) means
99 flag byte
09 data type ID byte: array of similar elements
A 06 number of bytes to follow
94 descriptor byte
9: one byte to follow
4: four bytes per element
08 type ID for floating point
C6
B D4 4 data bytes
DC
42
After the proper byte swapping, the system pressure (42-DC-D4-C6), expressed as a
floating point number is 110.4155731201 PSIG.
IEEE floating-point numbers are represented in 32 bits as shown below.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
exponent mantissa
sign
Convert hexadecimal words 1 and 2 (W1, W2) into decimal values ...
22204796 Rev. B, Version 3.10
Word Byte Symbol Hex Decimal

Lo 1 Lo W1LB C6 198
Lo 1 Hi W1HB D4 212
Hi 2 Lo W2LB DC 220
Hi 2 Hi W2HB 42 66
Determine the sign (positive = 0 or negative = 1) ...

Sign = (W2HB And 128) / 128, where And is defined as a bit-wise And
Sign = (66 And 128) / 128 = 0
Determine the exponent ...
Exponent = ((W2HB And 127) * 2) + INT (W2LB / 128), where INT is defined as
INTEGER
Exponent = ((66 And 127) * 2) + INT (220/128) = 133
Determine the mantissa...
Mantissa = ((((W2LB And 127) * 256) + W1HB) * 256) + W1LB
Mantissa = ((((220 And 127) * 256) + 212) * 256) + 198 = 6083782
Putting the 32 bit IEEE value together...
Value = (-1sign) * (2(exponent - 127)) * ((Mantissa * 2-23) + 1)
Value = (-10) * (2(133- 127)) * ((6083782 * 2-23) + 1) = 110.4155731201
NOTE
When Sign = Exponent = Mantissa = 0, Value = 0. This is a special case for the
above equation.
Example: Read Multiple Analog Channels

The procedure for reading multiple channels is the same as reading a single channel with
the exception of requesting more data. The message length in elements should be set as
desired but no more than 16 data at a time, because IRBUS can handle at most 16 data in
one query for the time being.
NOTE
A contiguous group of data (channels) must be read for a single command.
Example: Reading a Discrete Value

Reading discrete values from file number 11 or higher is the same as reading analog data.
To read a digital output (Channel 3, 188h) as a two-byte integer, the following command is
sent:
DLE STX DST SRC CMD STS TNS FNC Packet Total PLC5 System Size DLE ETX BCC
Offset Trans Address
10 02 0D 11 0F 00 A1 C2 68 00 00 01 00 07 00 0B BC 01 00 10 03 38
22204796 Rev. B, Version 3.10

The response to this command is:

10 02 11 0D 4F 00 A1 C2 99 09 03 42 01 00 10 03 48
Example: Reading Multiple Discrete Values

To read digital output channels 1-6 as integers, the following command is sent:
DLE STX DST SRC CMD STS TNS FNC Packet Total PLC5 System Size DLE ETX BCC
10 02 0D 11 0F 00 41 17 68 00 00 0C 00 07 00 0B BA 0C 00 10 03 2F
The response to this command is:

DLE STX DST SRC CMD STS TNS A B
10 02 11 0D 4F 00 41 17 99 09 19 42 00 00 00 00 00 00 00 00 01 00 00 00
B DLE ETX BCC

00 00 00 00 00 00 00 00 00 00 00 00 10 03 3D
Example: Reading Bit-Packed Discrete Data

Reading discrete values from file number 10 is to read the 16 bit-packed discrete values in
a two-byte integer format. When the following command is sent,
Offset Trans
10 02 0D 11 0F 00 61 C4 68 00 00 01 00 07 00 0A 0B 01 00 10 03 28
the response from this command is:

10 02 11 0D 4F 00 61 C4 99 09 03 42 28 10 10 10 03 4F
NOTE
The data value 10h in field B is transmitted as 10h 10h to be distinguished from the
control character DLE. Please see the DF1 Full-Duplex Protocol Message Frames
section for more details.
In the above example, the local data file type can be either bit or integer types. Local data
element B10:11 covers CMC data table address 176-191. Bit 10-15 is for digital output
channels 1-6. You can determine the remote trouble contact (Channel 3, J15-P3,4) by bit
12 in the returned integer. The table below graphically depicts the individual bit value for the
returned two-byte integer.
Response (hex) Bit 7 6 5 4 3 2 1 0
CMC Data Address 183 182 181 180 179 178 177 176
Byte 1 28 0 0 1 0 1 0 0 0
Bit 15 14 13 12 11 10 9 8
CMC Data Address 191 190 189 188 187 186 185 184
Byte 2 10 0 0 0 1 0 0 0 0
A bit response of 1 means that the output is ON and a response of 0 means that the output
is OFF.
22204796 Rev. B, Version 3.10

Command 0F/Function 67 - PLC5 Typed Write
CAUTION

The CMC is treated as a PLC5 when this command is issued. This command writes data to
the CMC starting at the specified data table address. You can write to a setpoint with either
an integer or floating point number.
Example: Presetting Analog Setpoints for 32-bit Values
To write 105.4 PSIG as a floating point number to the user pressure setpoint (CMC data
table address, 86h), issue the following command:
DLE STX DST SRC CMD STS TNS FNC Packet Total PLC5 System
10 02 0D 11 0F 00 81 CE 67 00 00 01 00 07 00 0B 86
A B DLE ETX BCC

99 09 06 94 08 CD CC D2 42 10 03 93

DLE STX DST SRC CMD STS TNS DLE ETX BCC
10 02 11 0D 4F 00 81 CE 10 03 44
The difficulty in setting 32-bit values is determining the four data bytes for the number you
want to send. The process required is ...
1. Determine the sign (positive = 0 or negative = 1). This is the first bit.
2. Divide the decimal value by 2 until the result is less than 2, but greater than 1. Count
the number of iterations required. Add 127 to the number of iterations. This result is the
exponent. Convert this result to binary. These are the next eight bits.
3. From the result obtained from step 2, subtract 1. Then, multiply this result by 2. If the
result is less than 1, then the value of the first mantissa bit is 0. Otherwise, the mantissa
bit is 1. If the result is greater than or equal to 1, then subtract 1 from the result and
proceed with step 3 until the result is 0 or you have gone through this process 23 times.
4. Combine all 32 bits from the steps above and convert this value to hexadecimal. These
32 bits are the 4 hexadecimal data bytes needed for the command.
As an example, we will start with the decimal value of 105.4.
1. Since this is a positive number, the first bit is 0.
22204796 Rev. B, Version 3.10

2. Determine the exponent bits by ...

Iteration Decimal Result
1 105.40000 / 2 = 52.700000
2 52.70000 / 2 = 26.350000
3 26.35000 / 2 = 13.175000
4 13.17500 / 2 = 6.587500
5 6.58750 / 2 = 3.293750
6 3.29375 / 2 = 1.646875
It took us six iterations to get the result to a number that is less than two and greater than or
equal to one. Now, we must add 127 for an exponent of 133. Converting this to binary, the
next eight bits are represented as 10000101.
3. Determine the mantissa bits by ...
Iteration Decimal Operation Result Bit
1 1.646875 - 1 * 2 = 1.29375 1
2 1.29375 -1*2= 0.5875 0
3 0.5875 *2= 1.175 1
4 1.175 -1*2= 0.35 0
5 0.35 *2= 0.7 0
6 0.7 *2= 1.4 1
7 1.4 -1*2= 0.8 0
8 0.8 *2= 1.6 1
9 1.6 -1*2= 1.2 1
10 1.2 -1*2= 0.4 0
11 0.4 *2= 0.8 0
12 0.8 *2= 1.6 1
13 1.6 -1*2= 1.2 1
14 1.2 -1*2= 0.4 0
15 0.4 *2= 0.8 0
16 0.8 *2= 1.6 1
17 1.6 -1*2= 1.2 1
18 1.2 -1*2= 0.4 0
19 0.4 *2= 0.8 0
20 0.8 *2= 1.6 1
21 1.6 -1*2= 1.2 1
22 1.2 -1*2= 0.4 0
23 0.4 *2= 0.8 0
From the table above, 10100101100110011001100 represent the next 23 bits.

4. Combining the bits in sign, exponent and then mantissa order ...
0100-0010-1101-0010-1100-1100-1100-1100
This converts to 42-D2-CC-CC in hexadecimal. To conform to DF1 floating point format, the
bytes are swapped as CC-CC-D2-42.
Example: Presetting a 16-bit Integer and 16-bit Fraction Analog Setpoint

To change the integer and fraction value for the user pressure setpoint to 105.4 PSIG,
issue the command below. The integer portion of the number 105 (00-69h) and the fraction
0.4 is converted to 4000 (0F-A0h). These four bytes are placed in field B in the order of (69-
00-A0-0F).
22204796 Rev. B, Version 3.10

DLE STX DST SRC CMD STS TNS FNC Packet Total PLC5 System Address
Offset Trans
10 02 0D 11 0F 00 41 D0 67 00 00 02 00 07 00 0B 86
A B DLE ETX BCC

99 09 05 42 69 00 A0 0F 10 03 C0

10 02 11 0D 4F 00 41 D0 10 03 82

Forcing a single coil to either ON or OFF. Refer to the table below for each coil supported
by the UCM-DF1 interface. An integer value of one or greater forces the coil to be ON. An
integer value of zero forces the coil to be OFF.
CMC Data Table CMC Data Table Coil Name
Address (decimal) Address (hex) (Write only)
220 DC Remote Acknowledge
221 DD Remote Reset
222 DE Remote Load
223 DF Remote Unload
224 E0 Remote Start
225 E1 Remote Stop
NOTE
For the CMC, forcing the above listed coils OFF is not meaningful because the
default state of each of the above coils is OFF. When using these commands, they
should be sent once (momentary) and the CMC will execute the commands.
NOTE
The Forcing Coil command will override the CMC’s current state. The forced state will
remain valid until the CMC next solves the coil. The coil will remain forced if it is not
programmed in the controller's logic.
22204796 Rev. B, Version 3.10

CAUTION
For all of the Remote Coils, the compressor’s REMOTE COMMUNICATIONS

DISABLED/ENABLED selector switch must be in the ENABLED position for these
commands to execute. When DISABLED, the CMC ignores these coils being forced
ON. The REMOTE COMMUNICATIONS DISABLED/ENABLED selector switch is
typically located on the front door of the Compressor’s Control Panel.
To remotely acknowledge the compressor’s alarm or trip condition, the following command
is issued:
Offset Trans
10 02 0D 11 0F 00 E1 F8 67 00 00 01 00 07 00 0B DC
A B DLE ETX BCC

99 09 03 42 01 00 10 03 BC

10 02 11 0D 4F 00 E1 F8 10 03 BA
The following command works the same:

Offset Trans
10 02 0D 11 0F 00 41 E3 67 00 00 02 00 07 00 0B DC
A B DLE ETX BCC

99 09 05 42 01 00 00 00 10 03 6E

10 02 11 0D 4F 00 41 E3 10 03 6F

Forces each coil in a series of contiguous coils to either ON or OFF. Refer to the data table
above for a coil list supported by the UCM-DF1 Interface.
NOTE
The Forcing Multiple Coils command will override the CMC’s current state. The forced
it is not programmed in the controller's logic.
To force a reset (CMC data table address, DDh) and start (CMC data table address, E0h)
of the compressor the following command is sent:
22204796 Rev. B, Version 3.10

Offset Trans
10 02 0D 11 0F 00 21 0C 67 00 00 08 00 07 00 0B DD
A B DLE ETX BCC

99 09 11 42 01 00 00 00 01 00 00 00 01 00 00 00 01 00 00 00 10 03 4F

10 02 11 0D 4F 00 21 0C 10 03 66
The number of contiguous coils is four (DD, DE, DF, and E0h). The message length of
integer elements is 8 and the number of data bytes in field B is 16.
Command 0F/Function A2 - SLC Typed Logical Read

The CMC is treated as an SLC5/04 when this command is issued. This function reads a
block of data from CMC starting at a specified data table address.
Example: Reading an Analog Value
To read the pressure setpoint (CMC data table address 86h) as a floating point number, the
following command is issued:
DLE STX DST SRC CMD STS TNS FNC Byte File File Ele S/Ele DLE ETX BCC
Size No. Type No. No.
10 02 0D 0B 0F 00 D4 19 A2 04 0B 8A 86 00 10 03 2B

DLE STX DST SRC CMD STS TNS Data DLE ETX BCC
10 02 0B 0D 4F 00 D4 19 CD CC D2 42 10 03 FF
The important command bytes are explained below:

Field Description
Byte Size The number of data bytes to be read.
File Number Address files 0-255 only. For CMC, file 10 is designated for discrete
only. File (11+N) is for the (N+1) th 256 entries in the CMC data table.
File Type 85h: bit
89h: integer
8Ah: float
Element Number Address elements 0-255 only. The address byte format is the same as
PLC5 for CMC.
254: (FE)
255: (FF-FF-00)
Sub-Element Number Not used, always 00h.
The four bytes in data field of the response message are converted to a floating point
number, 105.4 PSIG.
To read the pressure setpoint value as integer, the following command is sent:
10 02 0D 0B 0F 00 D4 27 A2 04 0B 89 86 00 10 03 1E
22204796 Rev. B, Version 3.10

10 02 0B 0D 4F 00 D4 27 69 00 A0 0F 10 03 86
The first two bytes in data field represent the integer portion, 106 (00-69h), of the setpoint.
The second two bytes represent the fraction portion, 4000 (0F-A0h), of the setpoint.
Example: Reading Multiple Analog Values

The following command reads analog inputs channels 3-9 as integer:
10 02 0D 0B 0F 00 D5 A9 A2 1C 0B 89 03 00 10 03 06

DLE STX DST SRC CMD STS TNS Data
10 02 0B 0D 4F 00 D5 A9 63 00 5C 21 09 00 0F 0A 20 00 D6 00 62 00 E7 0B
Data DLE ETX BCC

00 00 FF 0B 2E 00 66 14 BC 00 83 1E 10 03 C0
Example: Reading Single Discrete Data

input for emergency stop push button is located on J4-P5 (Channel 4). The CMC data table
address is ADh for the input in question. Therefore, to read the state of the emergency stop
push button as a two byte integer, the following command is issued:
10 02 0D 0B 0F 00 D6 79 A2 02 0B 89 AD 00 10 03 A5

10 02 0B 0D 4F 00 D6 79 01 00 10 03 49
The data response (01) means that the input is ON, or the emergency stop push button is
pressed.
Example: Reading 16 Bit-Packed Discrete Data

To read 16 bit-packed discrete values for digital outputs as a two-byte integer, the following
command is sent:
10 02 0D 0B 0F 00 E1 41 A2 02 0A 85 0B 00 10 03 79
Note that the file number must be 10. The local data file used to store the returned data can
be either bit (85h) or integer (89h) type. The response from this command is:
10 02 0B 0D 4F 00 E1 41 28 10 10 10 03 3F
Please refer to the PLC5 Typed Read command section for the method to interpret the 16-
bit discrete values.
22204796 Rev. B, Version 3.10
Command 0F/Function AA - SLC Typed Logical Write

The CMC is treated as a SLC5/04 when this command is issued. This command writes a
block of data to CMC starting at a specified data table address. You can write to a setpoint
with either an integer or floating point number.
Example: Presetting Analog Setpoint for 32-bit Value

To write 105.4 PSIG as a floating point number to the user pressure setpoint (CMC data
table address, 86h), issue the following command:
DLE STX DST SRC CMD STS TNS FNC Byte File File Ele S/Ele Data DLE ETX BCC
10 02 0D 0B 0F 00 E1 70 AA 04 0B 8A 86 00 CD CC D2 42 10 03 12

10 02 0B 0D 4F 00 E1 70 10 03 48
Example: Presetting a 16-bit Integer and 16-bit Fraction Analog Setpoint

To change the integer and fraction value for the user pressure setpoint to 105.4 PSIG,
issue the command below. The integer portion of the number 105 (00-69h) and the fraction
0.4 is converted to 4000 (0F-A0h). These four bytes are placed in field B in the order of (69-
00-A0-0Fh).
10 02 0D 0B 0F 00 E1 82 AA 04 0B 89 86 00 69 00 A0 0F 10 03 96

10 02 0B 0D 4F 00 E1 82 10 03 36

Forces a single coil to either ON or OFF. Refer to the CMC data table for each coil
supported by the UCM-DF1 interface. See the same example in the PLC5 Typed Write
command section for more details.
is issued:
10 02 0D 0B 0F 00 E1 A3 AA 04 0B 89 DC 00 01 00 00 00 10 03 36

10 02 0B 0D 4F 00 E1 A3 10 03 15
works the same:
10 02 0D 0B 0F 00 E1 AD AA 02 0B 89 DC 00 01 00 10 03 2E
22204796 Rev. B, Version 3.10


10 02 0B 0D 4F 00 E1 AD 10 03 0B

Forces each coil in a series of contiguous coils to either ON or OFF. Refer to the CMC data
table for a list of coils supported by the UCM-DF1 interface. To force a reset (CMC data
table address, DDh) and start (E0h) of the compressor, the following command is sent:
DLE STX DST SRC CMD STS TNS FNC Byte File File Ele S/Ele Data
10 02 0D 0B 0F 00 E2 3A AA 10 10 0B 89 DD 00 01 00 00 00 01 00 00 00
Data DLE ETX BCC

01 00 00 00 01 00 00 00 10 03 8E
NOTE
The byte size value 10h is transmitted as 10h 10h to be distinguished from the control
character DLE.

10 02 0B 0D 4F 00 E2 3A 10 03 7D
The number of contiguous coils is four (DD, DE, DF, and E0h). The assigned local
message buffer length is 8 integer elements, which is 16-byte long.
Allen-Bradley SLC 504 Example
Data Files
RSLogix 500 Ladder Diagram

The following ladder logic example is the fastest and most reliable method for gathering
data from a CMC.
22204796 Rev. B, Version 3.10

First Pass
S2:1 N7:0
0000 U
15 15
MSG
0001 Read/Write Message EN
Type Peer-To-Peer
Read/Write Read DN
Target Device 500CPU
Local/Remote Local ER
Control Block N7:0
Control Block Length 14
Setup Screen
N7:0 N7:0 N7:0

0002 U
12 10 15
N7:0 MSG
0003 Read/Write Message EN
13 Type Peer-To-Peer
Read/Write Read DN
Target Device 500CPU
Local/Remote Local ER
Control Block N7:20
Control Block Length 14
Setup Screen
N7:20 N7:20 N7:20

0004 U
12 10 15
N7:20 N7:0 N7:20 N7:0

0005 U
13 13 10 15
0006 END
UCM STS Error Codes

STS Code
(hex) Definition
00 Success - no error
10 Illegal command or function
30 Remote node host is missing, disconnected, or shutdown
3F Illegal CMC data address or count
D0 Illegal data type
E0 Cannot form CMC data table query/set list
NOTE
The UCM-DF1 driver does not support EXT STS. According to Allen-Bradley DF1
protocol convention, EXT STS is part of the message only if STS = F0h.
22204796 Rev. B, Version 3.10

When the CMC receives a DF1 command without any communication error and the
command is executed successfully, a normal response with status code 00h is returned.
If the UCM does not receive the command due to a communication error, no response is
returned and the command initiator will eventually time out.
If the UCM does receive the command, but detects error (invalid BCC/CRC...), control
characters DLE NAK is returned to the command initiator, which in turns retransmits the
command message and restarts a time out to wait for the response. This can be repeated a
few times depending on the limit preset for retransmission. Once the limit is exceeded, the
command initiator is informed of the failure and proceeds to the next command.
If the time out expired before a response is received, the command initiator sends out DLE
ENQ control characters to request a retransmission of the last response. It restarts a time
out and wait for the response. There is a limit on the number of inquiries allowed per
command message. When this limit is exceeded, the command initiator proceeds to the
next command.
When UCM receives DLE ENQ or DLE NAK message, it resends the last response to the
command initiator. When DLE ACK message is received by the UCM, no response is
returned.
When the UCM receives a command without any communication error, but cannot handle
it, the UCM will return an exception response with the appropriate status code informing the
command initiator of the nature of failure.
NOTE
The table below explains the meanings of different control symbols for DF1 protocol:
Control Symbol Definition

DLE ACK a message frame has been successfully received
DLE NAK a message frame was not received successfully
DLE ENQ request retransmission of a response from the destination node
Communication Parameters
Configuration of the UCM RS-422 port’s communication speed (baud rate), parity, number
of data bits, number of stop bits... is available through the Ingersoll-Rand Service Tool for
the UCM and will be configured by a certified Ingersoll-Rand Service Representative. The
settings should be the same as the 1770-KF2 interface module.
Network Setup
The network diagram that follows depicts the communication interface between Allen-
Bradley DF1 network and Ingersoll-Rand CMC Microcontroller.
The 1770-KF2 always acts as a slave. The slave cannot initiate a command; i.e., the UCM
cannot initiate a command over DH+ network. It only returns response messages to queries
that are addressed to them individually. Broadcast is not supported over the DF1 network.
22204796 Rev. B, Version 3.10

CMC Panel
CENTAC  Microcontroller
RS-232 Network for

Operator User Interface,
Twisted Pair Wires with
Common (3 Wires)
Serial Port
IRBUS (RS-485) Network (COM1)
for Base Control Modules
and Universal
Base Communication Modules,
Control Twisted Pair Wires with
Ground (3 Wires) INGERSOLL-RAND
Module
Service Tool
(BCM)
470
IRBUS ohm
Address: 1 IRBUS IN
(For IR Use)
IRBUS OUT
(For IR Use)
Service Tool
Base
Plug on Universal
Control Communication
Panel Door
Module Module (UCM)
(BCM) IRBUS
Address 4
IRBUS Network Card

Address: 2 Comm Port on
Server
INGERSOLL-RAND
Air System Controller
(ASC) Cat5
Cable
Universal Next CMC Panel(s) for
Comm. use in ASC
Module Ethernet to
(UCM) Modbus
IRBUS Modbus Network #1 Bridge
Address 5 Full or Half Duplex
RS-422 or RS-485 To DH+
Universal Network
Comm.
Module Allen-Bradley
(UCM) 1770-KF2
IRBUS Interface Module
DF1 Network
Address 6 Full Duplex RS-422A
22204796 Rev. B, Version 3.10

1770-KF2 Setup
A 1770-KF2 module links asynchronous devices (RS-422A or RS-232C) to an Allen-
Bradley Data Highway or Data Highway Plus network. The 1770-KF2 module has 8 switch
assemblies that let you select various communication options. The switch assemblies are
shown in the diagram below:
Switch Assembly Communication Option
SW-1 Asynchronous link features
SW-2, SW-3, SW-4 Node number
SW-5 Network link communication rate
SW-6 Asynchronous link communication rate
SW-7 DH/DH+ network link section
SW-8 RS-232C/RS-422A selection
CAUTION
The 1770-KF2 module reads the status of these communication option

switches only at power up, so you need to change switch settings with 1770-KF2
powered off.
SW-1 (Asynchronous Link Features)

The following table shows the different combinations available for setting the asynchronous
link with the 5 dipswitches of SW-1.
SW-1 Settings
3
Error Embedded (Duplicate 4
Protocol Check Parity Response 1 2 Message) (Hand 5
ON: ignore Shake)
OFF: accept
Full Duplex BCC None No OFF OFF OFF OFF OFF
Full Duplex BCC Even No ON OFF OFF OFF OFF
Full Duplex BCC None Yes OFF ON OFF OFF OFF
Full Duplex BCC Even Yes ON ON OFF OFF OFF
Full Duplex CRC None Yes OFF ON OFF OFF ON
CAUTION
Only the UCM-DF1 driver supports the full duplex options. Half duplex is not
supported.
SW-2, SW-3, SW-4 (Node Address)

These three switch assemblies are used to set the network node number of the 1770-KF2
module. Set both switches in SW-2 OFF for DH+ link because the node number should be
22204796 Rev. B, Version 3.10

a 2-digit octal number that identifies the 1770-KF2 as a unique node on DH+. Valid node
numbers for 1770-KF2 in DH+ network are 00 to 77 octal.
First digit (SW-2) should always be set to zero.
SW-2 Setting
1 2 Digit
OFF OFF 0
OFF ON 1
ON OFF 2
ON ON 3
Second and third digits:

SW-3, SW-4 Setting
1 2 3 Digit
OFF OFF OFF 0
OFF OFF ON 1
OFF ON OFF 2
OFF ON ON 3
ON OFF OFF 4
ON OFF ON 5
ON ON OFF 6
ON ON ON 7
SW-5 (Network Link Communication Rate)

Switch assembly SW-5 lets you select the communication rate for the 1770-KF2 module’s
network link (DH+). Set both switches ON for a network communication rate of 57,600 bits
per second. Be sure to set all modules on the same DH+ network for this communication
rate.
SW-6 (Asynchronous Link Communication Rate and Diagnostic Commands)

Switches #1, #2, #3 of SW-6 let you select the communication rate for the 1770-KF2
module’s asynchronous port. Meanwhile, switch #4 determines how 1770-KF2 module
treats diagnostic commands sent by a remote DH+ node. It is recommended to set at 9600
baud or higher, and execute received diagnostic commands.
SW-6 Setting
4
Execute received diagnostic commands ON
Pass any received diagnostic commands to the attached asynchronous device OFF
The available baud rate settings are shown below:

Baud Rate SW-6 Setting
(Bits per second) 1 2 3
110 OFF OFF OFF
300 ON OFF OFF
600 OFF ON OFF
1200 ON ON OFF
2400 OFF OFF ON
4800 ON OFF ON
9600 OFF ON ON
19200 ON ON ON
22204796 Rev. B, Version 3.10

SW-7 (Network Link Selection)

UCM only supports DH+ network. SW-7 should always select DH+.
Network SW-7 Setting
Mode 1 2
DH OFF OFF
DH+ ON OFF
SW-8 (RS-232C/RS-422A Selection)

The UCM-DF1 interface uses RS-422 communication. SW-8 should select RS422.
Communication SW-8 Setting
Type 1 2
RS-232C OFF ON
RS-422A ON OFF
Wiring Diagram for RS-422A
1770 KF2
Module
RS-422
GND UCM
1 RS-422
TX+ Cable not to exceed 4000 feet
14 RX+
TX-
25 RX-
RX+
16 TX+
RX-
18 TX-
20
22204796 Rev. B, Version 3.10

Documentation
An Electrical Schematic drawing is provided as standard after order placement. Control Panel
Outline drawings are optional. Logic diagrams are considered proprietary and are not available.
System Information
Status Codes
The following table lists the status codes for the Base Control Module (BCM) only. These
codes indicate every operating condition, both normal and abnormal, for the system. A code
always exists for the system; for example, Status 05h indicates that the system is running
properly.
These codes, except Status 00h and 05h, are shown on a blank screen in the upper left
hand corner of the Operator User Interface (OUI). Since Status 00h and 05h are normal
operating conditions, these codes are not displayed. When a code is displayed, contact
your local Ingersoll-Rand Service Representative.
Status
Code Definition Comments
00h Booting The BCM is in the boot process. This is a normal process during BCM power up.
This state will not be displayed.
01h Stay In Boot The BCM is held in boot mode by the hardware configuration. This condition exists
only when the boot jumper (hardware device) is plugged into the display (OUI) port.
This hardware jumper is only required when doing system level reprogramming of
the module.
02h ROM CRC Failed The BCM software is not valid. This condition occurs when the CRC (Cyclic
Redundancy Check) calculated by the module does not equal the CRC value written
to the module when programmed. This would typically occur when the programming
process is aborted (halted). The module must be reprogrammed.
03h Commanded To Boot The BCM is currently in the process of being programmed. If this message does not
disappear after programming is completed, power cycle the unit.
04h Invalid Application The BCM software has failed to operate properly. Cycling the power on the module
will restart the system. Once restarted, the program will operate properly until the
same condition reoccurs.
05h Application Running Normal operating condition. This state will not be displayed.
06h Fatal Exit Operating system error. Cycling the power on the module will restart the system.
Once restarted, the program will operate properly until the same condition reoccurs.
07h System Error Operating system error. Cycling the power on the module will restart the system.
08h Incompatible Software The BCM application software and tables are not compatible. The module must be
Versions reprogrammed.
09h A-D System Error Analog input system error. A hardware malfunction has occurred.
0Ah D-A System Error Analog output system error. A hardware malfunction has occurred.
0Bh Digital I/O System Error Digital input and output system error. A hardware malfunction has occurred.
0Ch Logic Engine System or Ladder logic processing system or loop task error. The module must be
Loop Task Error reprogrammed.
0Dh Comparator System Error Comparator system error. The module must be reprogrammed.
0Eh Operator User Interface Operator User Interface system error. Cycling the power on the module will restart
Error the system. Once restarted, the program will operate properly until the same
condition reoccurs.
0Fh Data Logging System Error Data logging system error. Cycling the power on the module will restart the system.
10h Low Power Power supply voltage (+24 VDC) dropped below minimum operating level. Check
power supply. Cycle power when voltage is within proper operating limits. Once
restarted, the program will operate properly until the same condition reoccurs.
22204796 Rev. B, Version 3.10

Status
Code Definition Comments
11h Task Overrun System processing capabilities do not meet requirements for operation. Cycling the
power on the module will restart the system. Once restarted, the program will
operate properly until the same condition reoccurs.
12h Watchdog Failure The internal backup system monitor is not operational. BCM hardware should be
replaced. Cycling the power on the module will restart the system. Once restarted,
the program will operate properly until the same condition reoccurs.
13h Intermodule Data Error An error has occurred while generating a message to be sent from one BCM to the
other BCM in a multi-module configuration. The module must be reprogrammed.
14h Calculation Block Error A stack underflow or overflow has occurred in a calculation block. The module must
be reprogrammed.
15h Interpolation System Error An error has occurred in the interpolation block. The module must be
reprogrammed.
16h Calibration System Error Occurs during initialization of the EEPROM block. The module must be
reprogrammed.
22204796 Rev. B, Version 3.10

Base Control Module (BCM)

Module Layout
J15-Digital Outputs, Channels 4-1

Pin 1 Pin 1 Pin 1 Pin 1
J10-Power Input
(24 VDC) F102-Fuse for AnalogI/O F101-Fuse for Operator
Pin 1 (J1, J2 and J3) User Interface (Display)
J9-Current Transformer F103-Fuse for Digital F100-Fuse for Base
Input (0-5 Amps) Inputs (J4 and J5) Module CPU Card
J8-Speed Sensor
Input (1-150 Hz)
Pin 1
J7-RS485 Serial
Data Link (IRBUS)
Pin 4
All Fuses are 5x20mm, GMA
J7-RS232 Serial 1.5 amp, Fast Blow

Pin 1
J6-RS232 Serial
Female DB9
Inputs (24 VDC),
Channels 9-16
Pin 1
Inputs (24 VDC),
Channels 1-8
Pin 1
J3-Analog Outputs
(4-20mA)
Channels 1-4
Pin 25
Pin 7 Pin 5 Pin 1
Pin 1
Pin 1 J1-Grounded Analog Inputs,
22204796 Rev. B, Version 3.10

Connector Description
Tag Type Channel Module Connector Mating Connector
J1 Grounded Analog Inputs, 4-20 mA 3-23 (12) Phoenix (2) Phoenix MDST
MDSTB 2, 5/2-G-5, 2, 5/24-3T-5, 08
08
J2 Floating Analog Inputs, 4-20 mA 1-2 (2) Phoenix MDSTB (2) Phoenix MDST
2, 5/2-G-5, 08 2, 5/4-3T-5, 08
J3 Analog Outputs, 4-20 mA 1-4 (3) Phoenix MDSTB (2) Phoenix MDST
2, 5/2-G-5, 08 2, 5/6-3T-5, 08
J4 Digital (Discrete) Inputs, 24 VDC 1-8 Phoenix MSTBA 2, Phoenix MSTB 2,
J5 9-16 5/10-G-5, 08 5/10-ST-5, 08
J6 RS232 Serial Data Link (Operator na 9 Position “D” Sub 9 Position “D” Sub
User Interface) Miniature (Female) Miniature (Male)
J7 RS232 Serial Data Link (OUI) na Phoenix MSTBA 2, Phoenix MSTB 2,
RS485 (IRBUS) Serial Data Link 5/9-G-5, 08 5/5-ST-5, 08
J8 Speed Sensor Input, Variable Phoenix MSTBA 2, Phoenix MSTB 2,
Reluctance 5/3-G-5, 08 5/3-ST-5, 08
J9 Current Transformer Input na Terminal Strip Wire Lugs
J10 Power na Phoenix MSTBA2, Phoenix MSTB 2,
5/5-G-5, 08 5/5-ST-5, 08
J12 Digital Outputs 13-16 (4) Phoenix MSTBA (4) Phoenix MSTB
J13 9-12 2, 5/8-G-5, 08 2, 5/8-ST-5, 08
J14 5-8
J15 1-4
NOTES:
1. BCM Weight: 1775 ± 177g [3.92 ± .39 lb.]
2. BCM Size: Length=355.6 mm [14.0 in] x Width=247 mm [9.7 in] x Depth=45 mm [1.8 in]
3. To ensure chassis ground, install 12-gauge ground strap between this module and the
NEMA enclosure. Place external tooth lock washer between this module and the ground
strap.
4. “na” is defined as “not applicable”.
5. All Phoenix connectors may be replaced with an equal supplier.
22204796 Rev. B, Version 3.10

Connector Input and Output (I/O)

Pin J1-Grounded Analog Inputs Pin J3-Analog Outputs Pin J8-Speed Sensor
1 Analog Input Channel 3 1 Analog Output Channel 1+ 1 SS+
2 Power 24 VDC, Channels 3 & 4 2 Power 24 VDC, Channels 1 & 2 2 SS-
3 Shield, Channels 3 & 4 3 Analog Output Channel 1- 3 SS Ground
4 Analog Input Channel 4 4 Analog Output Channel 2+
5 Analog Input Channel 5 5 Shields, Channels 1 & 2 Pin J9-Current Transformer
6 Power 24 VDC, Channels 5 & 6 6 Analog Output Channel 2- 1 CT+
7 Shield, Channels 5 & 6 7 Analog Output Channel 3+ 2 CT-
8 Analog Input Channel 6 8 Power 24 VDC, Channels 3 & 4
9 Analog Input Channel 7 9 Analog Output Channel 3- Pin J10-Power
10 Power 24 VDC, Channels 7 & 8 10 Analog Output Channel 4+ 1 Power +24V DC
11 Shield, Channels 7 & 8 11 Shields, Channels 3 & 4 2 Power Ground
12 Analog Input Channel 8 12 Analog Output Channel 4- 3 Chassis Ground
13 Analog Input Channel 9 4 Display Power +24VDC
14 Power 24 VDC, Channels 9 & 10 Pin J4-Digital Inputs 5 Display Power Ground
15 Shield, Channels 9 & 10 1 Power 24 VDC, Channels 1-8
16 Analog Input Channel 10 2 Digital Input Channel 1 Pin J12-Digital Outputs
17 Analog Input Channel 11 3 Digital Input Channel 2 1 Digital Output Channel 16
18 Power 24 VDC, Channels 11 & 12 4 Digital Input Channel 3 2 Digital Output Channel 16
19 Shield, Channels 11 & 12 5 Digital Input Channel 4 3 Digital Output Channel 15
24 Analog Input Channel 14 10 Ground, Channels 1-8 8 Digital Output Channel 13
25 Analog Input Channel 15
26 Power 24 VDC, Channels 15 & 16 Pin J5-Digital Inputs Pin J13-Digital Outputs
27 Shield, Channels 15 & 16 1 Power 24 VDC, Channels 9-16 1 Digital Output Channel 12
35 Shield, Channels 19 & 20 9 Digital Input Channel 16
36 Analog Input Channel 20 10 Ground, Channels 9-16 Pin J14-Digital Outputs
37 Analog Input Channel 21 1 Digital Output Channel 8
38 Power 24 VDC, Channels 21 & 22 Pin J6-RS232 (Display) 2 Digital Output Channel 8
39 Shield, Channels 21 & 22 1 Not Used 3 Digital Output Channel 7
40 Analog Input Channel 22 2 Receive Data (RxD) 4 Digital Output Channel 7
41 Analog Input Channel 23 3 Transmit Data (TxD) 5 Digital Output Channel 6
42 Power 24 VDC, Channel 23 4 Not Used 6 Digital Output Channel 6
43 Shield, Channel 23 5 Signal Ground 7 Digital Output Channel 5
44 Spare 6 Not Used 8 Digital Output Channel 5
45 Spare 7 Not Used
46 Power 24 VDC, Spare 8 Not Used Pin J15-Digital Outputs
47 Shield, Spare 9 Not Used 1 Digital Output Channel 4
48 Spare 2 Digital Output Channel 4
Pin J7-RS232 (Display) / RS485 (IRBUS) 3 Digital Output Channel 3
Pin J2-Floating Analog Inputs 1 Receive Data (RxD) (Display) 4 Digital Output Channel 3
1 Analog Input Channel 1+ 2 Transmit Data (TxD) (Display) 5 Digital Output Channel 2
2 Power 24 VDC, Channel 1 3 Signal Ground (Display) 6 Digital Output Channel 2
3 Analog Input Channel 1- 4 Data Link 1+ (IRBUS) 7 Digital Output Channel 1
4 Shield, Channel 1 5 Data Link 1- (IRBUS) 8 Digital Output Channel 1
5 Analog Input Channel 2+ 6 Data Link Ground (IRBUS)
6 Power 24 VDC, Channel 2 7 Data Link 1+ (IRBUS)
7 Analog Input Channel 2- 8 Data Link 1- (IRBUS)
8 Shield, Channel 2 9 Data Link Ground (IRBUS)
22204796 Rev. B, Version 3.10

Operator User Interface Module (OUI)

Module Layout
Side View
J1-RS232 Port
Pin 1
J3-RS232 Port
Pin 1
Pin 1
J2-Input Power
Tag Type Module Connector Mating Connector
J1 RS232 Port 9 Position “D” Sub 9 Position “D” Sub

Miniature (Female) Miniature (Male)
J2 Input Power Phoenix MSTBA2, Phoenix MSTW2,
5/2-G-5, 08 5/2-ST-5, 08
J3 RS232 Port Phoenix MC 1.5/5- Phoenix MC 1.5/5-
G-3.81 ST-3.81
NOTES:
1. OUI Weight: 410 g [0.90 lb.]
2. OUI Size: Length=267 mm [10.5 in] x Width=175 mm [6.9 in] x Depth=60 mm [2.4 in]

Pin J1-RS232 Port Pin J2-Input Power Pin J3-RS232 Port
1 No Connection 1 +12 To +24 VDC 1 RS232 Data Link Tx
(VPOWER)
2 Transmit (TX) 2 Ground (GND) 2 RS232 Data Link Rx
3 Receive (RX) 3 Common (Com)
4 No Connection 4 IRBUS RS485 Data Link (DL+)
5 Signal Common 5 IRBUS RS485 Data Link (DL-)
6 No Connection
7 No Connection
8 No Connection
9 No Connection
22204796 Rev. B, Version 3.10

OUI PCB Assembly (Cover Removed)

Showing replaceable fuse
J1
9 Position
Fast-Acting, SMF, .75A, 125V "D" Sub
Littlefuse 0451.750 or 0453.750
or Equivalent Connector
J3
5 Pin
Connector
F2
J2
2 Pin
Connector
CMC User Interface/Bezel Cleaning Instructions

The following procedure is recommended to clean the CMC User Interface vinyl overlay
material and/or the User Interface bezel.
1. Stop the compressor and depress the maintained ‘Emergency Stop’ push-button, this
will prevent an inadvertent start up or trip of the compressor during the cleaning
process.
2. Dampen a soft cloth or paper towel with water and wipe any dust, dirt or liquids from the
surface of the User Interface, do not use an abrasive pad or brush to clean the surface
of the User Interface vinyl overlay or bezel.
3. If more aggressive measures are required to clean the User Interface and/or bezel
surface use a mild non-abrasive household cleaner (such as Formula 409, Fantastik,
etc.) sprayed or wiped directly onto the surface to be cleaned. Dampen a soft cloth or
paper towel with water and wipe any remaining cleaner from the surfaces.
Ingersoll-Rand Company recommends the following for cleaning the OUI and bezel:
Cleaners: Water or mild household cleaner, no petroleum or acetone based fluids.
Cleaning wipes: Soft cotton clothe or paper towels.
Backlight Replacement Procedure

Tools Needed:
1. Flat blade screwdriver with a small tip (1/8 inch)
2. Number 1 Phillips Screwdriver
3. Electrostatic Discharge Strap Connected to Earth Ground
22204796 Rev. B, Version 3.10

Step 1 Step 2
J1 User
Terminal
J3 User
Terminal
Tx
Rx
COM
DL+
DL-
Remove Unplug connector
Lift cover to remove cabling and remove nylon
cable retainer screws
J2 Display
Power
+
-
Loo
s en
scr
ew
s, s
l ide
righ
t
Step 3 Step 4
Remove screws from the

lower printed circuit
board, then use a
screwdriver to gently pry
the backlight panel loose.
Use circular stand-offs to The backlight is part of a larger panel

rest screwdriver shaft that is removed as an assembly.
against while prying
backlight panel out.
22204796 Rev. B, Version 3.10

Step 5 Step 6
Insert screws being careful
Backlight panel is not to over tighten.
inserted into display
between the circuit board
and the LCD glass with
the white plastic backing
sheet and wires facing
toward the circuit boards.
Slide the backlight panel

in place and align the
screw holes so the screws
may be inserted and
tightened. Route wiring, replace nylon cable retainers,
insert backlight plug, replace main cover
and connect power and communication
cable to complete installation.
22204796 Rev. B, Version 3.10

Universal Communication Module (UCM) Optional

Module Layout
Side View
J2-Service/Modem J1-Microcontroller/Network
J3-Input Power
(RS232) Port (RS422/RS485) Port
Pin 1 Pin 1 Pin 1
Top View
RS232 Activity IRBUS RS485

Indicator Activity Indicator
RS422/485 Activity Indicator
22204796 Rev. B, Version 3.10

Tag Type Module Connector Mating Connector
J1 Microcontroller/Network Phoenix MSTBA2, Phoenix MSTBW2,
(RS422/485) Port 5/8-G-5, 08 5/24-ST-5, 08
J2 Service/Modem (RS232) 9 Position “D” Sub 9 Position “D” Sub
Port Miniature (Female) Miniature (Male)
J3 Input Power Phoenix MSTBA2, Phoenix MSTW2,
5/2-G-5, 08 5/2-ST-5, 08
NOTES:
1. UCM Weight: 410 g [0.90 lb.]
2. UCM Size: Length=136 mm [5.4 in] x Width=143 mm [5.6 in] x Depth=31 mm [1.2 in]

Pin J1-Microcontroller/Network Port Pin J2-Service/Modem Port Pin J3-Input Power
1 IRBUS RS485 Datalink + (DL+) 1 No Connection 1 +12 To +24 VDC (VPOWER)
2 IRBUS RS485 Datalink - (DL-) 2 Transmit (TX) 2 Ground (GND)
3 Ground (GND) 3 Receive (RX)
4 RS422/485 Transmit + (TX+) 4 No Connection
5 RS422/485 Transmit - (TX-) 5 Signal Common
6 RS422/485 Receive + (RX+) 6 No Connection
7 RS422/485 Receive - (RX-) 7 No Connection
8 Ground (GND) 8 No Connection
9 No Connection
22204796 Rev. B, Version 3.10

UCM Port Activity LEDs

The UCM has three light emitting diodes (LEDs) to indicate the activity of the RS232,
RS422/485 and the IRBUS RS485 ports. The following table indicates the different states of
these ports.
RS422 IRBUS
RS232 RS485 RS485 UCM State
off off off No power (24 VDC)
on off off Boot mode, check A1 switch for being non-zero (cycle
power to exit boot mode)
on on on Running, but no communication on any port
on on blinking Multi-module job with inter-module communication
blinking on blinking Service Tool in use
blinking on on Service Tool in use, but no response from BCM … check
connection between BCM and UCM
on blinking blinking MODBUS communication in use
on blinking on RS-422 port in use, but no response from BCM … check
connection between BCM and UCM or Modbus and DF1
address
blinking blinking blinking All blinking together imply a continuous reboot or application
problem
UCM Communications Parameters

The UCM has three communication ports, RS232, RS422/485 and IRBUS RS485. Each of
these ports has its own communication parameters that it supports.
Service Tool Modbus/DF1 IRBUS

Parameter RS-232 RS-422/485 RS-485
Distance 50 feet (15.2 meters) 4000 feet (1218.3 Meters) 100 feet (30.4 Meters)
Baud Rate 9600 300, 600, 1200, 2400, 9600
9600, 19200, 38400
Parity None None, Even, Odd None
Data Bits 8 8 8
Stop Bits 1 1, 1.5, 2 1
Configurable No Yes* No
* A certified Ingersoll-Rand Service Representative will provide this configuration.
22204796 Rev. B, Version 3.10

RS422/485 Network Wiring Diagram - Full Duplex
Compressor Panel #n B
SERVER
(Modbus Master) Modbus Address - nn
120 VAC IRBUS Address - any The maximum
distance of a
MODBUS Network is
To Server's 4000 electrical feet;
Network Card i.e., the length of the
wire from the Ethernet
Bridge (Location A) to
the last compressor's
Universal
Ethernet Communication
Module (Location B).
Ethernet Switch Compressor Panel #6
Cable 3 Com
The maximum number
Cat5 or
of devices (nodes) on
Better Modbus Address - 06
120 VAC IRBUS Address - any a MODBUS Network is
30.
Compressor Panel #5 A terminating resistor

is not required at the
end of the network.
Modbus Address - 05
IRBUS Address - any
Rx- Rx+ Tx+ Tx-
Ethernet / Compressor Panel #4

Modbus RS-422
Modbus Address - 04
Bridge IRBUS Address - any 2 Twisted Pair Wires
174 CEV with Ground (5 Wires)
300
24VDC + Compressor Panel #3
Fused -
Modbus Address - 03
IRBUS Address - any
RS-422
2 Twisted
Pair Wires
Plus Gnd.
(5 Wires) To
To
To
To
Connect Power Power
BCM BCM
Supply Supply
Ground
One End
Only 24+ Gnd DL+ DL- Gnd Tx+ Tx- Rx+ Rx- Gnd RS-422 24+ Gnd DL+ DL- Gnd Tx+ Tx- Rx+ Rx- Gnd
RS-232 RS-232
Power RS-485 RS-422/485 DB-9
2 Twisted Power RS-485 RS-422/485 DB-9
Pair Wires
with Ground
(5 Wires)
Universal Communication Module (UCM) Universal Communication Module (UCM)
Modbus Address - 01 Modbus Address - 02

(Set through software) (Set through software)
Compressor Panel #1 Compressor Panel #2
22204796 Rev. B, Version 3.10

RS422 Network Wiring Diagram - Half Duplex
Compressor Panel #n B
SERVER
(Modbus Master) Modbus Address - nn
120 VAC IRBUS Address - any The maximum
distance of a
MODBUS Network is
4000 electrical feet;
i.e., the length of the
To Server's wire from the Ethernet
Network Card Bridge (Location A) to
the last compressor's
Universal
Ethernet Communication
Module (Location B).
Ethernet Switch Compressor Panel #6
Cable 3 Com
The maximum number
Cat5 or
of devices (nodes) on
Better Modbus Address - 06
120 VAC IRBUS Address - any a MODBUS Network is
30.
Compressor Panel #5 A terminating resistor

is not required at the
end of the network.
Modbus Address - 05
IRBUS Address - any
Rx- Rx+ Tx+ Tx-
Ethernet / Compressor Panel #4

Modbus RS-422
Bridge Modbus Address - 04
IRBUS Address - any Twisted Pair Wires
174 CEV with Ground (3 Wires)
300
24VDC + Compressor Panel #3
Fused - A
Modbus Address - 03
IRBUS Address - any
RS-422
Twisted Pair
Wires
With Ground
(3 Wires) To
To
To
To
Connect Power Power
BCM BCM
Supply RS-422 Supply
Ground
Twisted Pair
One End
Wires with
Only 24+ Gnd DL+ DL- Gnd Tx+ Tx- Rx+ Rx- Gnd 24+ Gnd DL+ DL- Gnd Tx+ Tx- Rx+ Rx- Gnd
RS-232 Ground (3 RS-232
Power RS-485 RS-422/485 DB-9 Power RS-485 RS-422/485 DB-9
Wires)
Universal Communication Module (UCM) Universal Communication Module (UCM)
Modbus Address - 01 Modbus Address - 02

(Set through software) (Set through software)
Compressor Panel #1 Compressor Panel #2
22204796 Rev. B, Version 3.10

Terminating Resistor – Modbus Network

The RS422/485 circuitry built into each UCM supports Alternate-Fail-safe AC Termination.
This termination circuitry enhances the UCM's ability to operation in harsher (electrically
noisier) environments. Since this circuitry is built into the product, no external terminating
resistor is required. For a thorough discussion of the various termination techniques, please
refer to "A Comparison of Differential Termination Techniques", National Semiconductor
Application Note 903 (AN-903), August 1993. This application note can be obtained from
the Internet at "www.national.com".
Terminating Resistor – IRBUS Network

Due to the data rate the RS485 IRBUS is provided with termination resistors mounted
inside the panel. The value of each resistor is 470 ohms. The purpose of the termination is
to prevent reflections. Reflections occur when a signal encounters different impedance and
is reflected back towards the source. This can corrupt the intended data transmission.
Where IRBUS is networked with other panels two termination resistors are required, one at
each end of the network.
22204796 Rev. B, Version 3.10

Typical System Layout
Operator User Interface (OUI)
24 VDC Power
RS232
Base Control Module

(BCM) #1
470
ohm
IRBUS OUT
IRBUS IN
120/240 VAC
24 VDC Power
IRBUS (RS485)
IRBUS (RS485)
Universal
Communications
Module (UCM)
Base Control Module Power Supply

(BCM) #2
24 VDC
Service Tool
Port Not Shown
24 VDC
Optional
Equipment
22204796 Rev. B, Version 3.10

Network Diagram
CMC Panel
RS-232 Network for

Operator User Interface,
Twisted Pair Wires with
Common (3 Wires)
Serial Port
IRBUS (RS-485) Network (COM1)
for Base Control Modules
and Universal
Base Communication Modules,
Control Twisted Pair Wires with
Ground (3 Wires) INGERSOLL-RAND
Module
Service Tool
(BCM)
470
IRBUS ohm
Address: 1 IRBUS IN
(For IR Use)
IRBUS OUT
(For IR Use)
Service Tool
Base
Plug on Universal
Control Communication
Panel Door
Module Module (UCM)
(BCM) IRBUS
Address 4
IRBUS Network Card

Address: 2 Comm Port on
Server
INGERSOLL-RAND
Air System Controller
(ASC) Cat5
Cable
Universal Next CMC Panel(s) for
Comm. use in ASC
Module Ethernet to
(UCM) Modbus
IRBUS Modbus Network #1 Bridge
RS-422 or RS-485
Universal
Comm. To next CMC Panel
Module or any other
(UCM) Modbus compliant
IRBUS Modbus Network #2 product
RS-422 or RS-485
22204796 Rev. B, Version 3.10

Technical Specification
DESCRIPTION OF STANDARD PHYSICAL DATA
Switches, Lights and Push Buttons Panel Construction
Control Power On/Off switch... activates panel power and prelube pump NEMA 12 enclosure
Compressor trouble light (red) Formed and welded 11-gauge carbon steel cabinet, 14 gauge door
Emergency stop pushbutton Door gasket with butt type hinges
Back panel for component mounting
Microprocessor OUI
240x128 pixel LCD graphic display window
Dimensions
Tabbed folders for ease of navigation Panel1 Panel2 Controller Board
Status Bar with compressor state Height 54 in (137.2 cm) 54 in (137.2 cm) 14.0 in (35.5 cm)
Eighteen screens of compressor information and setup data Width 32 in (81.3 cm) 35 in (88.9 cm) 9.7 in (24.6 cm)
Left/Right/Up/Down/Return push buttons Depth 12 in (30.5 cm) 14 in (35.6 cm) 1.0 in (2.5 cm)
Acknowledge/Reset push buttons 1 - No Starter or size 5 starter panels
Start/Stop push buttons 2 - with size 5DP or size 6 starter panels
Load/Unload push buttons
Contrast Button Weight
Without starter 300 lb. (136.1 kg)
Event Log With size 5 starter 350 lb. (158.8 kg)
With size 6 starter 375 lb. (170.1 kg)
Most recent 224 events with name, time, date and value
Logged events Component Data
Alarms Canadian Standard Association (CSA)
Trips Underwriters Laboratories (UL) approved components
Command key press (local and remote) Control Wiring
E-Stop pressed
High voltage and low voltage wiring segregation
Module control power up and down
TEW wire with PVC insulation (meets NEMA VM-1 for Flame
MinLoad reset
Retardant
Analog input failed
105 degC temperature rise on insulation
Setpoint change (local and remote)
600 V rating, 18 gauge for instrumentation and signal, 16 gauge for
Automatic start and stop (when Auto Hot Start purchased)
control
Surge Unload
Heat shrink wire markers for harness
Compressor Started
Clip-on wire markers internal to panel
Driver Failed to Start
Wire Ferules
Loss of Motor Power
Language and Units of Measure Terminal Blocks
300 VAC design for #22 through #10 wire size
Language and Units of Measure Sets Tubular clamp contacts and tang clamping collar, DIN Rail mounted
Two Language and Units of Measure sets are select-able from the display.
NOTE: The English language and psia, degF, mils are standard for all Push Buttons/Selector Switches/Indicating Lights
units. English and kPA, degC, microns are the default alternate Corrosion resistant, Oil-tight
language unless otherwise specified. Other Units of Measure are Designed and manufactured to NEMA 4/12/13
available upon request. Pilot lights are 120 VAC full voltage type
Languages Control Interposing Relays
Arabic Bulgarian Chinese Croatian
Two normally open and Two normally closed contacts rated:
Czech Danish Dutch French
1/3HP 10AMP 120VAC
Finnish German Greek Hungarian
1/2HP 10AMP 240VAC
Italian Norwegian Polish Portuguese
10AMP 28VDC
Romanian Russian Slovakian Slovenian
Coil rated 120 VAC
Spanish Swedish Turkish
Units of Measure Contacts
Available upon request. Normally Open, 5 amps at 120 VAC
Control Functions Pressure Transducers

Modulate or Autodual Ranges 0-50 PSIG, 0-200 PSIG, 0-500 PSIG, 4-20 mA Output
Channel
Manual Valve control for compressor setup 7/16-20 SAE or 1/4" NPT pressure port fitting
High motor load limit (controls maximum opening of inlet valve) Hirschmann GSA3000N connection head fitting for machine mounted
MinLoad (controls minimum opening of inlet valve) model
Partial Unload on Surge Temperature Transducers
Moves inlet valve to minimum load setting and bumps the bypass valve 0-500 degF operating range, 4-20 mA transmitter
open to exit the surge condition 100 ohm platinum, TCR=0.00385
Minimizes duration and magnitude of pressure drop from surge Four compression type terminals
Surge Indexing NEMA 4 rating
Actual/Alarm/Trip Functions Vibration Transmitters

Low oil pressure Eddy current probe
High/low oil temperature Vibration range 0-4 mils, Frequency range 5-3000 Hz
High air temperature into last compression stage Output Channel 4-20 mA and 200 mV/Mil, Supply voltage 18-50 VDC
High stage shaft vibrations, single plane Barrier type screw terminals, DIN rail mountable
Hardened against 150 MHz and 440 MHz radio interference
Alarm Function
Surge Wiring Harness
One wiring harness per device
Trip Function NEMA 4 rated
Low seal air (interlocked w/ prelube pump operation)
Display Functions (Read Only)
Motor current
System air pressure
Copper Ground Bar
22204796 Rev. B, Version 3.10

Automatic Starting
OPTIONS Automatic Hot Start
REMOTE FUNCTIONS DISABLED/ENABLED Selector Switch
Analog Inputs (Monitor, Alarm and Trip) Solenoid Valves for Intercoolers
Any Temperature CMC settable start up pressure setpoint
Any Pressure Post Run Water Flow Timer
Any Vibration Automatic Cold Start
Any 4-20 mA signal CONTROL POWER LOCAL/OFF/ COLD Selector Switch
Strobe Light
Digital (Discrete) Inputs (Monitor and Alarm or Trip) Solenoid Valves for Intercoolers and Instrument Air Line
Low water flow CMC settable start up pressure setpoint
Dirty inlet filter (switch supplied loose) Post Run Water Flow Timer
Dirty oil filter Start Timer
Low oil level Lube Oil Alarm Bypass Timer
High condensate level (common for all traps)
High motor temperature
Any Discrete Input COMMUNICATIONS OPTIONS
Panel Enclosures Communications Card(s)
Cooing Fan with Filter Up to three cards per module RS-422/485
110/115 VAC, 50/60 Hz, 0.24 Amps, 20 Watts Local/Network Selector Switch
Air flow with filter 36 CFM (61 M3/Hr)
NEMA 4 Enclosure
Direct CMC Communication with RS422/RS-485
Space Heater, Vortex Tube Cooler Requires programming application by customer
Utilizes standard MODBUS protocol or Allen-Bradley DF1 protocol for
NEMA 4X Enclosure PLC2, PLC5 and SLC500 devices
Space Heater, Vortex Tube Cooler
Stainless steel or epoxy coated carbon steel Hard Wired Communication
Space Heater REMOTE FUNCTIONS DISABLED/ENABLED Selector Switch
120 VAC, 120 Watts, finned strip heater Contacts for Remote Start/Stop, Load/Unload, Acknowledge/Reset
Bimetallic baseboard type thermostat set at 45 degF (7 degC) Trouble Indication Contacts (Alarm and Trip, Alarm Only or Trip Only)
Vortex Tube Cooler Remote 4-20 for Pressure Setpoint
25 SCFM (42 NM3/Hr) at 100 PSIG (7 BarG) of compressed air Running Unloaded Contact
1500 BTU/Hr (378 kCal/Hr), Thermostat set at 90 degF (32 degC)
Solenoid operated valve, Air Filter Air System Controller (ASC)
Type Z Purge Features
Select-able quick and normal flow rates with meters Sequencing, load sharing and energy management for eight (8)
Differential pressure switch set at 0.2 inches (5 mm) of water compressors (more depending on network design and hardware)
Loss of purge indication, Relief valve, Warning label A CMC Communication Adapter mounted in each CMC panel
Max distance from last compressor to Communication Adapter is 4000
Fused Control Power Disconnect feet (1218 meters)
Rotary handle through door, 30 amp fuse Modbus to Ethernet Bridge
Ground Fault Protector for UL Panels Ethernet Switch
120 Vac circuits protected against ground fault currents. ASC Personal Computer (running Server Software)
Control Electrical Package (Standard on CV) Pentium IV processor (Minimum 1.4GHz microprocessor)
256 MB RAM (512 Recommended)
Prelube Pump Motor Starter
144 MB 3.5 inch diskette drive
Two horsepower and less
Network Interface card
Available voltages 380, 460, 575 VAC
Recordabel/Rewriteable CD ROM Drive
Maximum voltage rating 600 VAC, 10 Amp rating, 120 VAC coils
144 MB 3.5 inch diskette drive
IEC Style
Minimum 40.0 GB hard drive
Heater Contactor
IEC Style, Adjustable ambient compensated overloads
Available voltages 380, 460, 575 VAC CUSTOMER RESPONSIBILITIES
Maximum voltage rating 600 VAC, 10 Amp rating, 120 VAC coils
Control Power Transformer Three phase power
Machine tool type, 230, 460, 575 VAC to 120/95 VAC Clean, dry control air 80-150 PSIG (5.62-10.55 kg/cm2)
500 VA or optional 1000 and 1500 VA, 50 or 60 Hz Control air tubing from control air header, 1/4 in (0.635 cm) FNPT
Transient Voltage Surge Suppressor connection
UL 1449 Listed Mount and wire external switches and field wired devices
Tested to ANSI / IEEE C62.41 category A and B environments.
Tuning control parameters for system
Stage Data Package (Standard on CV) Current transformer – instrument grade
Interstage Air Pressure and Temperature each stage 0-5 amp
Better than 1% accuracy
Alarm Horn
80-95 dBA, 2900 Hz
CONTROLLER OPERATING ENVIRONMENT
Running Unloaded Shutdown Timer
Timing range and mode select-able through CMC Electrical Operation
Water Solenoid Post Run Timer 115 VAC ±5%
Timing range and mode select-able through CMC 24 VDC Instruments except three wire RTDs
32 VA of AC power requirement
Inlet Valve Tight Closure 50/60 Hz AC supply frequency
Keeps inlet valve closed until motor reaches full speed
0-30 second timer range settable by IR Service Tech Temperatures
Operating temperature 32 to 140 degF (0 to 60 degC)
Diesel Engine Driven Compressor Control Storage temperature -4 to 158 degF (-20 to 70 degC)
Steam and Gas Turbine Driven Compressor Control Relative Humidity

95% (maximum) non-condensing
Main Motor Starter (Wye-Delta)
NEMA Size 5 or 6
Open transition type, Ambient compensated overloads
DOCUMENTATION
Available voltages 380, 460, 575 VAC, 120 VAC coils Instruction book
Electrical schematic
Power Regulating Transformer Panel Outline drawing (Optional)
120 VAC, 60 Hz, 250 VA
-65% Input Channel line variation, Output Channel +5-10% NEMA
Specification
±15% Input Channel line variation, Output Channel ±3%
22204796 Rev. B, Version 3.10

Glossary Auto-Dual — The control mode that automatically unloads a

modulating compressor when the bypass valve position
reaches a specified value or the check valve closes. Once
The following glossary is generic; therefore, unloaded, this control mode will automatically reload the
some terms do not apply to all CMC systems. compressor when the system pressure drops below a
specified value.
Auto-Dual Unload Timer  The time delay, in seconds, at
AB — See Allen-Bradley.
which the machine will be unloaded after the bypass valve
Absolute Address — For Modbus compliant devices, the
has passed and stayed below the unload point when
specific memory location for a coil, discrete input, register or
Autodual is active.
analog input. The address is a five-digit number.
Auto-Hot Start — A control mode that automatically starts
Accelerometer — An instrument used to measure
and loads the compressor on a low-pressure condition.
acceleration. These instruments are typically used for bearing
Auto-Reload — The portion of Auto-Dual control mode that
analysis.
automatically reloads the compressor when the pressure
Actuator — The device on a control valve that provides the
drops below a specified value.
power to move the valve to a position. Typically, this power is
Auto-Start Pressure  The system pressure, in pressure
supplied through control air to open (for the inlet valve) and
setpoint units, at which the machine will start when either
close (for the bypass valve). For “fail-safe” operation, a spring
auto hot or cold start is active.
is used to drive the valve in the opposite direction.
Axial Position — The position of the rotating assembly with
Address — This term is used by PLC manufacturers to
respect to the horizontal axis of the pinion.
indicate a specific memory location within the unit. These
locations typically reference the value for data items like analog
Baud Rate — Unit of signaling speed for data
inputs, analog outputs, digital inputs, digital outputs, coils and
communications. The speed in baud is the number of line
intermediate computational states. Through these memory
changes (in frequency, amplitude, etc.) or events per
locations, the current system pressure, first stage vibration and
second. At low speeds each event represents only one bit
discharge air temperature can be determined.
and baud rate equals bits per second. As speed increases,
Alarm — The term used to indicate that an abnormal condition
each event represents more than one bit, and baud rate
exists that should be addressed by an operator. This condition
does not truly equal bits per second.
has not reached a level that would shut down the compressor.
BCM — Base Control Module. The device of the CMC that
Alert — See Alarm.
receives all of the compressor inputs and outputs and makes
Allen-Bradley — A manufacturer of control products, most
decisions about how the compressor is to operate.
notably PLCs. These PLCs are used for various industrial
Binary Signal — The type of signal used in
applications including controlling compressors.
communications. Binary refers to the smallest size of data
American Wire Gage (AWG) — The measurement system
being transmitted, a bit.
used to indicate the diameter of the wire. The gage number
Blow-off Valve — Also know as a bypass valve or anti-
increases as the wire diameter decreases.
surge valve. This valve protects the compressor from surge
Ambient Control — See Polytropic Head.
by bypassing a percentage of the compressed air to the
Analog Input — An electrical device, which represents a
atmosphere, which results in keeping the compressor loaded
specific real world pressure, temperature, vibration or current.
above the surge point.
As these items fluctuate, the electrical signal to and from the
BPS — Bits per second. Unit of signaling speed for data
microprocessor board also fluctuates proportionally to the
communications.
amount of change. The electrical signal is typically in the form
Bridge — A device which forwards traffic between network
of a current that ranges from 4 to 20 milli-amps in magnitude.
segments based on data link layer information. These
Analog Output — An electrical signal, which typically
segments would have a common network layer address.
represents the inlet and bypass valve position. As these valves
Bypass Valve — See blow-off valve.
fluctuate, the electrical signal to and from the microprocessor
board also fluctuates proportionally to the amount of change.
CAT 5 — Category 5. A classification of cable used in
The electrical signal is typically in the form of a current that
twisted-pair networks.
ranges from 4 to 20 milli-amps in magnitude.
CE Mark — The CE Mark is a combination of various
Auto-Cold Start — A control mode that automatically
individual European standards into one set of standards for
energizes the panel power, opens cooling water flow valve to
the entire European community. The Mark is a self
the coolers, turns on seal air, starts and loads the compressor
declaration and self marking process. Once you have proven
on a low pressure condition.
that the particular equipment meets the requirements of CE
22204796 Rev. B, Version 3.10

Mark and have the data to back it up, you may mark the Data Link — A direct serial data communications path
product with the CE Mark. between two devices without intermediate switching nodes.
Citect — One of many SCADA software packages that can be Data Highway Plus — A communication protocol used by
used for air system integration. Allen-Bradley PLC 5 and SLC500 PLCs.
Choke — Also know as stonewall. This is the maximum flow DCS — See Distributed Control System.
that can be compressed by a given machine’s hardware degC — Degrees Celsius, Centigrade.
configuration. degF — Degrees Fahrenheit.
Circuit Breaker — An automatic switch that stops the flow of DH+ — See Data Highway Plus.
electric current in a suddenly overloaded or abnormally Derivative Mode — Provides a change in the control
stressed electric circuit. variable (through the inlet or bypass valve) based on the rate
CMC — Centac MicroController. of change of the error (setpoint pressure minus system
CMC System — Any combination of CMC control components pressure).
which when combined create a control system. The typical Derivative Constant — Also know as the rate time, in units
CMC system consists of a Base Control Module (BCM), of seconds.
Operator User Interface (OUI), and Power Supply (PS). A Design Point — The pressure and capacity required at
common variation on the typical system is the addition of a maximum ambient conditions.
Universal Communications Module (UCM). Digital Device — A device, which is either on or off; e.g., the
Coast Timer — The time interval, in seconds, between a N.C. contact on the seal air switch.
compressor stop or trip and the motor coming to a complete Discrete Device — See Digital Device.
stop. The timer is used to inhibit restarting. Discharge Pressure — The gas pressure between the last
Compressor Load, Load — The power consumption of the stage of compression and the check valve.
compressor. It is typically indicated in amps, kilowatts, SCFM, Distributed Control System — A system that attempts to
etc. control an entire plant or process with multiple independent
COM Port — See Serial Port. local controllers by networking these local controllers to a
Control Transformer — The transformer that is used to central computer through digital communications. These
reduce the incoming voltage (for the prelube pump motor and central computers can be a PC, PLCs or other larger
oil heater) to approximately 120 volts for controlling the CMC systems. Some manufacturers of these DCS products are
electrical devices (relays, power supply, etc.). Bailey, Honeywell, Allen-Bradley, Siemens, and others.
Control Valve — The inlet or bypass valve used to control Drain Wire — An insulated wire in contact with a shield
pressure or current. throughout its length, and used for terminating the shield.
Control Variable, Process Variable — The variable being Dry Contacts — A set of contacts that require a power
regulated. When at MinLoad the control variable is load for the source supplied by others (customer). This is the normal
inlet valve and System Pressure for the bypass valve. When at type of contacts that we provide.
MaxLoad the control variable is load and when loaded the
control variable is System Pressure. Electro-pneumatic — A term used to indicate a combination
CSA Approval — Canadian Standards Association approval is of electronics and pneumatics. In the past, we provided
required for all electrical devices shipped into Canada. This electro-pneumatic panels as standard equipment. With the
association is similar to UL for the United States and CE for advent of digital computers, most all control panels are
Europe. electronic.
CT — Current Transformer. ERAM — Erasable Random Access Memory.
CT Input Channel — The current transformer input channel. Event — The control transfer or “rule(s)” as used in State
CT Ratio — Current Transformer Ratio. The current Logic to transfer from one state to another.
transformer ratio used in displaying the motor current; e.g.
600:5 = 120. FactoryLink — One of many SCADA software packages
Current Transformer — The electrical device used to that can be used for air system integration.
measure the amps of the main drive motor. For our standard FLA — Motor Full Load Amps. The motor amperage at full
application, we only measure the current from one of the three load, this value is found on the motor nameplate.
phases. Flexible Conduit — Small diameter hose, made of plastic
coated aluminum, which is used to enclose wire from the
Daisy Chain — A method of wiring a communication network. control panel to machine mounted instruments.
This method starts with the “master” and it is wired directly to Fused Disconnect — As a safety precaution, this option
compressor #1. Compressor #2 is wired to compressor #1, removes power from the panel before the door is opened. By
then compressor #3 is wired to compressor #2. turning the rotary door handle, the panel power is
terminated. The disconnect would have to be mounted
22204796 Rev. B, Version 3.10

external to the panel enclosure. The short circuit capacity, (BCM), Universal Communication Modules (UCM) and
maximum ground fault, motor full load amps, motor locked rotor Operator User Interfaces (OUI).
amps and motor voltage must be known to size the disconnect
properly. Loopback — A diagnostic test in which a transmitted
communication signal is returned to the sending device after
Ground — A connection to earth or to some extended passing through all or part of the communication network.
conducting body that serves instead of the earth. This test compares the transmitted signal to the received
Ground Loop — An unwanted, continuous ground current signal. The test passes if the signals are identical.
flowing back and forth between two devices that are at different
ground potentials. MA, mA — Milliampere
Grounded System — An electrical system in which at least Maintained Contact — A contact closure that remains
one point (usually a wire) is intentionally grounded. closed.
MaxLoad — The message displayed on the OUI Status Bar
Head — See Polytropic Head. when the machine is running at MaxLoad.
High Load Limit — See HLL MinLoad — The message displayed on the OUI Status Bar
HLL — High Load Limit. The load that the controller maintains when the machine is running at MinLoad.
when at MaxLoad. MMI — Man Machine Interface. The term used to indicate
the device or method used for a human to interface with a
I/O — See Input/Output. machine. Typically these interfaces are LCD displays or
IBV — Inlet Butterfly Valve. See Inlet Valve. computer screens. For the CMC, the MMI is the Operator
IEC — International ElectroTechnical Commission is the User Interface (OUI).
governing body of Europe for electrical equipment and codes. Modbus — A sixteen-bit communication protocol originally
IGV — Inlet Guide Vanes. See Inlet Valve. developed for Modicon PLCs. This protocol has become a
Inlet Unload Position — The position of the inlet valve when in defacto standard for industrial equipment.
the unloaded state. Modicon — A PLC brand name manufactured by Schneider
Inlet Valve — The device used on the inlet pipe to the Automation.
compressor that restricts the amount of airflow to the Modulate — The control mode that opens and closes
compressor. This valve can be a butterfly valve or a valve with (modulates) the inlet or bypass valve to maintain a constant
inlet guide vanes. discharge pressure. This is the primary control mode for
Input/Output —The hardware interface between the centrifugal compressors.
compressor and the control system. This term generically Momentary Contact — A contact closure that closes and
applies to the entire interface circuit including sensor, wiring, then opens.
and junction points.
Instrument Air — The air supply to the panel that is directed to N.C. — Normally Closed. Used to indicate the state of a
the power air system for the inlet and bypass valves and the contact when no power is applied.
compressor seals. N.O. — Normally Open. Used to indicate the state of a
Integral Mode — Provides a change in the control variable contact when no power is applied.
(through the inlet or bypass valve) based on the time history of Natural Curve — The set of pressure and capacity points
the error (setpoint pressure minus system pressure). that define the operating characteristic of the centrifugal
Integral Time Constant—This value is expressed in repeats compressor.
per second and represents the number of times per second the Natural Surge — The point on the natural curve that is
integral mode acts. represented by the maximum pressure and minimum
Intellution — One of many SCADA software packages that capacity.
can be used for air system integration. NEMA — National Electrical Manufacturers Association.
Interface — The hardware or software device used to Network — A series of points, nodes or devices connected
communicate between products. by some type of communication medium.
Interlock — An electrical function that prevents the
compressor from starting in the event that the function has not On-Line/Off-Line — Control mode that allows the system
been satisfied. For example, the seal air interlock prevents the discharge pressure to fluctuate between two pressure
compressor from starting until the seal air pressure is setpoints. The compressor will load when the actual
adequate. pressure is below the lower setpoint pressure and will unload
IRBUS — The proprietary communication protocol used to when it reaches the higher setpoint pressure. This type of
communicate to and from one or many Base Control Modules control mode is normally used on reciprocating and rotary
compressors.
22204796 Rev. B, Version 3.10

OUI — Operator User Interface. The device on the CMC that RS-232 to RS-422/485 Converter — A hardware device that
gathers user inputs and provides compressor operating status. electrically converts an RS-232 signal into an RS-422 or RS-
485 signal.
Parity — The addition of non-information bits to make up a RS-422 — Electronic Industries Association interface
data transmission block that ensures the total number of 1s is standard that specifies electrical characteristics for balanced
either even (even parity) or odd (odd parity). This is used to circuits and extends transmission speed and distances
detect errors in communication transmission. beyond RS-232. This standard is a balanced voltage system
Partial Unload — See Surge Absorber. with a high level of noise immunity.
Password — The four digit parameter used to determine when RS-485 — Electronic Industries Association balanced
the user can modify setpoints. The range of this password is interface standard similar to RS-422, but uses a tri-state
0000 to 9999. driver for multi-drop applications.
PID — Proportional, Integral, Derivative. The parameters used RTD — Resistance Temperature Detector. An instrument
to adjust the behavior of PID control loops. that measures temperature by detecting the voltage across
PLC — Programmable Logic Controller. This hardware device the RTD material (mostly platinum). The temperature is
is configurable such that many types of analog and digital determined because as the temperature increases the
inputs and outputs can be utilized to control various industrial resistance increases.
products. RTU — Remote Terminal Unit. A device typically used for
PLC 5 — Type of Allen-Bradley PLC used for large data acquisition to gather data. By using this definition, the
applications. Base Control Module is an RTU.
Pneumatic — Run by or using compressed air.
Polytropic Head — The energy in foot-pounds to transfer one SCADA — Supervisor Control and Data Acquisition. The
pound of given gas from one pressure level to another. (ft-lb/lb) generic classification for software that gathers data for
Positioner — The device on a control valve that instructs the control of industrial products.
actuator how much (to what position) to move the valve. Sequencer — A hardware or software device that controls
PROM — Programmable Read Only Memory. the order in which compressors starts, stops, loads and
Proportional Mode — Provides a change in the control unloads. Some sequencers also control loading and
variable (through the inlet or bypass valve) proportional to the unloading through incremental pressure setpoints among the
error (setpoint pressure minus system pressure). compressors. For example, in a three-compressor
Proportional Band Constant — The percent change in application the setpoints may be 101 psi for compressor #1,
system air pressure that causes a percent change in the valve 100 psi for compressor #2 and 99 psi for compressor #3.
position. This value is dimensionless. Assuming the pressure transducers were calibrated within
Protocol — A formal set of conventions governing the one psi of each other and the machines were running
formatting and relative timing of message exchange between unloaded, this configuration would drive compressor #1 to
two communication systems. load first when the pressure dropped to 101 psi.
Serial Device — A Personal Computer (PC), Programmable
RAM — Random Access Memory. Logic Controller (PLC), Distributed Control System (DCS) or
Relative Address — For Modbus compliant devices, the four- any other device that can transmit, receive and interpret an
digit address within the range of 0-9999. The relative address RS422/485 formatted signal.
can be determined from the absolute address by deleting the Serial Port — The RS-232 connection on the back of a PC
type (the ten-thousandth place) and subtracting one. to communicate with other equipment. This connection is
Reload Percent — The reload pressure, in percent of user typically referred to as COM1. A single PC can have more
pressure set point, at which the machine will load when than one serial port.
Autodual is active. Service Tool — The software used on the PC to configure,
Rigid Conduit — Small diameter pipe, made of carbon steel tune, record and log data from the CMC.
with welded connections, which is used to enclose wire from Service Tool Plug — A port on Panel door to provide
the control panel to machine mounted instruments. This conduit access to IRBUS Network. Requires Laptop and external
is typically used in hazardous area classifications. UCM.
Rise To Surge — The amount of pressure from the operating Setpoint Ramp Rate — The gradual increase of the system
pressure to the natural surge pressure. This amount is usually pressure set point during a loading operation of the
expressed in percent. compressor. The ramping of the system pressure set point
RS-232 — Electronic Industries Association interface standard helps to smooth the transition and prevents a pressure
between data terminal equipment and data communication overshoot in the air system upon initial compressor loading.
equipment, using serial binary data interchange. This is the Shielded Wire — Wire that has a sheet, screen or braid of
most common standard used by industry. metal, usually copper, aluminum, or other conducting
22204796 Rev. B, Version 3.10

material placed around or between electric circuits or cables or Terminal Block — A device that is used to connect to wires.
their components, to contain any unwanted radiation, or to Typically, these blocks are provided for customer field wiring
keep out any unwanted interference. to the panel and when one wire is to be connected to
SLC500 — Type of Allen-Bradley PLC used for relatively small multiple devices.
applications and is lower in cost than an equivalent PLC 5. Terminating Resistor — A resistor placed at the end of a
Start Timer — The time interval, in seconds, between pressing communication network for absorbing or sufficiently
the Start button and the compressor is running at full speed. attenuating signals incident on it so that they are not
The timer is used to transition wye delta starters, inhibit reflected back into the transmission line at amplitudes where
loading, de-energize the prelube pump, and disable the they would cause distortion of the data signal. Typically, a
alternate alarm and trip setpoints. resistor is placed at each end of the network to help
State — A task that is currently being executed in State Logic. eliminate noise.
Only one state is active at one time. Thermocouple — A device used to measure temperatures
State Logic — State Logic is an alternative to traditional accurately and consists of two dissimilar metals joined so
control languages used for machines, systems, and processes. that a voltage is generated between to the contacts of the
State Transition — The movement from one state to another two metals as the temperature changes.
based on one or more events. Throttle Limit — See TL.
Status Bar — The Status Bar provides four distinct types of Throttled Surge — The condition created by closing the
information (Compressor Operating State, Compressor Status, inlet valve past the surge point to maintain constant
Compressor Control Location and Page Number). This region pressure.
is always visible from any folder and page combination. Tight Closure — A term used to describe the inlet valve
Stonewall — See Choke. position when the compressor is not running and starting.
Surge Absorber — The reaction of the control system to a The inlet valve ideally is closed tightly when stopped to
surge that pops the bypass valve open by a small percentage prevent reverse rotation of the compressor if the check valve
to get the compressor out of the surge condition. This feature is fails. Also, to reduce the load on the compressor during
initiated by surge detection. starting, the inlet valve can be held closed for a short period
Surge Anticipation — The ability of a control system to of time (less than thirty seconds) after the start button is
prevent surge by predicting that a surge is about to happen. pushed. This is most typically done on compressors at high
Surge Detection — The ability of a control system to indicate altitude, most notably snow making applications. Bearing
that a surge has happened. This feature is important because a analysis must be done prior to using this option.
persistent surge condition can damage the compressor. Once TL — Throttle Limit. Establishes the minimum flow through
detected, the control system can respond to the event by taking the machine when loaded, it is the maximum point of inlet
a corrective action; i.e., by opening the bypass valve. valve throttling. If system demand is below this throttle point,
Surge Indexing — A method of automatically increasing the the compressor must bypass air to maintain pressure
setting of TL upon a surge. setpoint or unload.
Surge Indexing TL — The setpoint at which the inlet valve TL increment value — When Surge Indexing is enabled, the
controls to MinLoad. TL increment value is the amount added to the Surge
Surge Line — A series of points that represent natural surge Indexing TL upon a surge. The Surge Indexing TL will stop
for various inlet pressure conditions. being incremented when and if the value reaches MaxLoad.
Surge PTX — Surge Pressure Transducer. Surge PTX is Transducer — An electrical device that provides a usable
mounted between the last compression stage and the check output (4-20 mA, 0-5 vDC, etc.) in response to a measured
valve. property (pressure, temperature, etc.).
Surge Sensitivity — A setpoint that is used to indicate the Transformer — An electrical device that transfers energy
magnitude of pressure and current changes that occur during a from one circuit to another by electromagnetic induction.
surge condition. This setpoint determines when the control Transient Voltage Surge Suppressor — An electrical
system detects a surge. device that prevents temporary over-voltages of short
Surge Unload — The reaction of the control system to a surge duration (typically associated with lightning strikes and
that unloads the compressor to exit the surge condition. This ground faults on an ungrounded system) from damaging
feature is initiated by surge detection. other electrical equipment.
Switch, Ethernet — A device connected to several other Transmitter — An electrical device that sends the digital
devices. Transfers messages across the network. representation of a real measured value (e.g., pressure,
System Pressure — The pressure at the location of the temperature), to the BCM in the control panel for analysis
system pressure transducer. and display.
Turndown — The amount of capacity that can be decreased
from full load (maximum load) at a constant pressure before
22204796 Rev. B, Version 3.10

the bypass valve begins to open to avoid surge. This amount is

usually expressed as a percent of full load capacity.
TVSS — See Transient Voltage Surge Suppressor.
Twisted Pair Wire — Paired cables allow balanced signal
transmission, which results in signals with low noise. Due to the
improved noise immunity of twisted pairs, data speeds are
usually higher than those of multi-conductor cables.
UCM — Universal Communications Module. The device that

allows outside systems to communicate with the CMC.
UL — Underwriter’s Laboratory.
Ungrounded System — An electrical system, without an
intentional connection to ground.
Unload — The operating mode that passes a small amount of
air through the compressor and bypasses it to the atmosphere.
In this mode, the inlet valve is cracked open a small amount
and the bypass valve is fully open. This mode is used when
starting the compressor before loading, stopping the
compressor and during periods of no demand.
Unload Point — The bypass valve position, in percent open, at
which the Autodual unload timer will start timing to unload the
compressor when Autodual is active.
User Pressure Set Point — The local control pressure set
point.
Valve Stroking — The process of calibrating the valves to

align the fully open position to 100 percent and the fully closed
position to 0 percent of output signal.
VDC — Volts Direct Current
Voltage Regulator — An electrical device that maintains
voltage to a predefined level.
Wait Timer — The delay interval, in seconds, between power

up and the ready state.
Wire Gage — See American Wire Gage.
Wonderware — One of many SCADA software packages that
can be used for air system integration.
Z-Purge — Required when the customer environment is

Division 2. A Type Z Purge reduces the classification within an
enclosure from Division 2 too non-hazardous. When provided,
a NEMA 4 or NEMA 4X enclosure is required. Hand valve
selectable quick and slow purges, with flow meters are
provided to regulate the amount of gas entering the panel. A
differential pressure switch is wired to a light on the front of the
panel to indicate if there is a loss of purge gas. A relief valve is
installed to prevent over-pressurization and a warning label,
text below, is affixed to the front of the panel.
22204796 Rev. B, Version 3.10


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INGERSOLL-RAND

Copyright 1996-2003 Ingersoll-Rand Company

Printing Date: 24 March 2003

22204796 Rev. B, Version 3.10

22204796 Rev. B, Version 3.10

22204796 Rev. B, Version 3.10

What’s New About the 3.10 Release

22204796 Rev. B, Version 3.10

22204796 Rev. B, Version 3.10

General - CMC Panel

22204796 Rev. B, Version 3.10

Figure 1: Compressed Air System

Control is accomplished by Natural

modulating the inlet valve within Constant Pressure Line

the compressor's throttle range. Surge Line Design

or all of the air to atmosphere.

reaching the surge line. Bypass

capacity setting. Modulate

from design to zero.

Energy Saving Control - Autodual

to the pressure setpoint and Unload

time period called the Unload Capacity

22204796 Rev. B, Version 3.10

How does Constant Pressure Modulation Work?

Figure 4: Performance Control

22204796 Rev. B, Version 3.10

desired discharge pressure.

algorithm could be eliminated by manually

22204796 Rev. B, Version 3.10

Figure 6 shows the

combinations of Pb and It.

Proportional Band and

variables used internally Time

by the control system to

act) anticipates where the process is

heading by looking at the time rate of

Derivative action depends on the slope

22204796 Rev. B, Version 3.10

settings for different process control.

Motor Current, MinLoad and MaxLoad

22204796 Rev. B, Version 3.10

When ambient conditions produce the

setpoint is reached, the compressor

Capacity - Mass Flow

Figure 10: MinLoad

22204796 Rev. B, Version 3.10

System Compressor Compressor Open Position

22204796 Rev. B, Version 3.10

22204796 Rev. B, Version 3.10

Optional Motor Power (kW)

Optional Ambient Control (Polytropic Head)

and diffusers) running compressor is capable of is fixed. If

22204796 Rev. B, Version 3.10

Insufficient Rise To Surge

Changes in System Discharge Pressure

Rapid System Demand Changes Figure 15: Changes in Discharge Pressure

22204796 Rev. B, Version 3.10

Incorrect Instrumentation Output

Incorrect Valve Response