M90/91 OPLC

Installation Guide
Models M90/91

This guide provides basic information for Unitronics M90/91 OPLC.

General Description
M90/91 OPLC are palm-sized programmable logic controllers that comprise a built-in operating
panel containing a multilingual text-only LCD screen and a keypad. M90 series offer a single text line
display. M91 offers 2 text lines.
All M90/M91 controllers
comprise a serial port. M90
series support RS232 only.
An M91 serial port may be
set to RS485.
CANbus and SMS/GSM
support are modeldependent features.

Communications

I/O Options

Programming

M90/91 supports digital, high-speed,

and analog I/Os via:
Onboard I/O Configuration
Differs from model to model.
I/O Expansion Modules
Via I/O expansion port, most
M90 models can be
expanded by up to 64 I/Os,
M91 by up to 96. Check the
specifications of your model
for details.
Write both the HMI and Ladder control
application using U90 Ladder freeware.

The M90 User Guide and the products technical specification sheet contain additional information.
These documents are located on the Unitronics Setup CD. They may also be downloaded from the
Technical Library at www.unitronics.com.

Standard Kit Contents

M90 or M91 controller

Programming cable + RS232 adapter

Mounting brackets (x2)

Rubber seal (mounted in back of panel)

I/O connectors (x2)

Unitronics Setup CD

5-pin CANbus connector and CANbus network termination resistor (CANbus models)

Unitronics

10/06

M90/91 OPLC

Danger Symbols
When any of the following symbols appear, read the associated information carefully.
Symbol

Caution

Meaning

Description

Danger

The identified danger causes physical and property damage.

Warning

The identified danger could cause physical and property damage.

Caution

Use caution.

Before using this product, the user must read and understand this document.
All examples and diagrams are intended to aid understanding, and do not guarantee operation.
Unitronics accepts no responsibility for actual use of this product based on these examples.
Please dispose of this product according to local and national standards and regulations.
Only qualified service personnel should open this device or carry out repairs.
Failure to comply with appropriate safety guidelines can cause severe injury or property damage.
Do not attempt to use this device with parameters that exceed permissible levels.
To avoid damaging the system, do not connect/disconnect the device when power is on.

Environmental Considerations
Do not install in areas with: excessive or conductive dust, corrosive or flammable gas,
moisture or rain, excessive heat, regular impact shocks or excessive vibration, in accordance
with the standards given in the products technical specification sheet.
Ventilation: 10mm space required between controllers top/bottom edges & enclosure walls.
Do not place in water or let water leak onto the unit.
Do not allow debris to fall inside the unit during installation.
Install at maximum distance from high-voltage cables and power equipment.

Mounting
Dimensions

Unitronicsnitronic

Installation Guide

10/06

Panel mounting
Before you begin, note that the
mounting panel cannot be more
than 5 mm thick.
1. Make a panel cut-out
measuring 92 x 92 mm
(3.622 x 3.622).
2. Slide the controller into the
cut-out, ensuring that the
rubber seal is in place.
3. Push the 2 mounting brackets
into their slots on the sides of
the controller as shown in the
figure to the right.
4. Tighten the bracket screws
against the panel. Hold the
bracket securely against the
unit while tightening the
screw.
5. When properly mounted, the
controller is squarely situated
in the panel cut-out as shown
in the figure to the right.

Unitronics

10/06

M90/91 OPLC

DIN-rail mounting
1. Snap the controller onto the DIN rail
as shown in the figure to the right.

2. When properly mounted, the controller

is squarely situated on the DIN-rail as
shown in the figure to the right.

I/O Modules
The controllers offer an on-board I/O configuration that differs according to the controller model; I/O
wiring diagrams are in the controllers technical specification sheet.
Additional I/Os may be integrated into the system via I/O Expansion Modules that you plug into the
controllers I/O expansion port. Note that the relevant wiring diagrams are in the modules technical
specification sheet, and that an I/O adapter is required for most modules.

Wiring: General
Do not touch live wires.
Unused pins should not be connected. Ignoring this directive may damage the device.
Caution

To avoid damaging the wire, do not exceed a maximum torque of 0.5 Nm (5 kgfcm).
Do not use tin, solder, or any substance on stripped wire that might cause the wire
strand to break.

Use crimp terminals for wiring; use 26-14 AWG wire (0.13 mm 22.08 mm2).
1. Strip the wire to a length of 70.5mm (0.2500.300).
2. Unscrew the terminal to its widest position before inserting a wire.
3. Insert the wire completely into the terminal to ensure a proper connection.
4. Tighten enough to keep the wire from pulling free.

Unitronicsnitronic

Installation Guide

10/06

Power Supply
The controller requires an external 12 or 24VDC power supply, according to the controller model.
Exact information may be found in the controllers technical specification sheet.
A non-isolated power supply can be used if a 0V signal is connected to the chassis.
You must use an external circuit protection device.
Install an external circuit breaker. Guard against shortcircuiting in external wiring.
Double-check all wiring before turning on the power
supply.
Do not connect either the Neutral or Line signal of the
110/220VAC to devices 0V pin.
In the event of voltage fluctuations or non-conformity to
voltage power supply specifications, connect the device
to a regulated power supply.

M91 only: Earthing the Power Supply

To maximize system performance, avoid electromagnetic interference by:
Mounting the controller on a metal panel.
Earthing the controllers power supply: connect one end of a 14 AWG wire to the chassis
signal; connect the other end to the panel.
Note: The wire used to earth the power supply must not exceed 10 cm in length. If your
conditions do not permit this, do not earth the power supply

Communication Ports
Note that different controller models offer different serial and CANbus communication options. To
see which options are relevant, check your controllers technical specifications.
Turn off power before making communications connections.
Caution

Note that the serial ports are not isolated.

Signals are related to the controllers 0V; the same 0V is used by the power supply.
Always use the appropriate port adapters.

Serial Communications
Both M90 and M91 comprise an RJ-11 type serial port that supports RS232.
An M91 serial port can be set to either RS232 or RS485 according to jumper settings.
Use RS232 to download programs from a PC, and to communicate with serial devices and
applications, such as SCADA.
Use RS485 to create a multi-drop network containing up to 32 devices.

Unitronics

10/06

M90/91 OPLC

Pinouts
The pinouts below show the signals between the adapter and port.
RS232

RS485

Controller Port

Pin #

Description

Pin #

Description

1*

DTR signal

A signal (+)

0V reference

(RS232 signal)

TXD signal

(RS232 signal)

RXD signal

(RS232 signal)

0V reference

(RS232 signal)

6*

DSR signal*

B signal (-)

Pin #1

*Standard programming cables do not provide connection points for pins 1 and 6.
M91 only: RS232 to RS485: Changing Jumper Settings
To access the jumpers, open the controller and then remove the modules PCB board.
Before you begin, turn off the power supply, disconnect and dismount the controller.
When a port is adapted to RS485, Pin 1 (DTR) is used for signal A, and Pin 6 (DSR)
signal is used for signal B.
If a port is set to RS485, and flow signals DTR and DSR are not used, the port can also
be used to communicate via RS232; with the appropriate cables and wiring.
Before performing these actions, touch a grounded object to discharge any electrostatic
charge.
Avoid touching the PCB board directly. Hold the PCB board by its connectors.

1. Turn power off before opening the

controller.
2. Locate the 4 slots on the sides of the
controller.
3. Using the blade of a flat-bladed
screwdriver, gently pry off the back of
the controller.

4. Gently remove the top PCB board:

a. Use one hand to hold the top-most
PCB board by its top and bottom
connectors.
b. With the other hand, grasp the
controller, while keeping hold of the
serial ports; this will keep the
bottom board from being removed
together with the top board.
c. Steadily pull the top board off.
5. Locate the jumpers, and then change
the jumper settings as required.
Jumper settings are shown on
page 7.
6

Unitronicsnitronic

Installation Guide

10/06

6. Gently replace the PCB board. Make

certain that the pins fit correctly into
their matching receptacle.
a. Do not force the board into place;
doing so may damage the
controller.
7. Close the controller by snapping the
plastic cover back in its place. If the
card is placed correctly, the cover will
snap on easily.

RS232/RS485 Jumper Settings

RS232/RS485 Jumper Setting

RS485 Termination

To use as

Jumper 1

Jumper 2

Termination

Jumper 3

Jumper 4

RS232*

ON*

RS485

OFF

*Default factory setting.

Unitronics

10/06

M90/91 OPLC

CANbus Communications
Certain controllers comprise a CANbus port. Use
this to create a decentralized control network of
up to 63 controllers using Unitronics proprietary
CANbus protocol.

24V Power
Supply

+
Circuit
protection
device

The CANbus port is galvanically isolated.

CANbus Wiring
Use twisted-pair cable. DeviceNet thick
shielded twisted pair cable is recommended.

121
terminating
resistor

-V
L
PE
H
+V

Network terminators: These are supplied with the

controller. Place terminators at each end of the
CANbus network.
Resistance must be set to 1%, 121R, 1/4W.

-V
L

Connect ground signal to the earth at only one

point, near the power supply.

PE
H
+V

The network power supply need not be at the

end of the network
CANbus Connector

-V
L
PE
H
+V

121
terminating
resistor

The information in this document reflects products at the date of printing. Unitronics reserves the right, subject to all applicable laws, at any time, at its sole
discretion, and without notice, to discontinue or change the features, designs, materials and other specifications of its products, and to either permanently or
temporarily withdraw any of the forgoing from the market.
All information in this document is provided "as is" without warranty of any kind, either expressed or implied, including but not limited to any implied warranties of
merchantability, fitness for a particular purpose, or non-infringement. Unitronics assumes no responsibility for errors or omissions in the information presented in
this document. In no event shall Unitronics be liable for any special, incidental, indirect or consequential damages of any kind, or any damages whatsoever arising
out of or in connection with the use or performance of this information.
The tradenames, trademarks, logos and service marks presented in this document, including their design, are the property of Unitronics (1989) (R"G) Ltd. or other
third parties and you are not permitted to use them without the prior written consent of Unitronics or such third party as may own them
5409-0400-4

Unitronicsnitronic