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9. TROUBLESHOOTING

9.1 Alarms and warning list

When a fault occurs during operation, the corresponding alarm or warning is displayed. If any alarm or
warning has occurred, refer to section 9.2 or 9.3 and take the appropriate action.
After its cause has been removed, the alarm can be deactivated in any of the methods marked in the
alarm deactivation column.
Alarm deactivation
Display Name Power
Error reset CPU reset
OFF ON
10 Undervoltage
12 Memory error 1
13 Clock error
15 Memory error 2
16 Encoder error 1
17 Board error
19 Memory error 3
1A Motor combination error
20 Encoder error 2
24 Main circuit error
25 Absolute position erase (Note 2)
30 Regenerative error (Note 1) (Note 1) (Note 1)
Alarms

31 Overspeed
32 Overcurrent
33 Overvoltage
34 CRC error
35 Command frequency error
36 Transfer error
37 Parameter error
45 Main circuit device overheat (Note 1) (Note 1) (Note 1)
46 Servo motor overheat (Note 1) (Note 1) (Note 1)
50 Overload 1 (Note 1) (Note 1) (Note 1)
51 Overload 2 (Note 1) (Note 1) (Note 1)
52 Error excessive
8E Serial communication error
88 Watchdog
92 Open battery cable warning
96 Home position setting warning
9F Battery warning
E0 Excessive regenerative warning
Warnings

E1 Overload warning
Removing the cause of occurrence
E3 Absolute position counter warning
deactivates the alarm automatically.
E4 Parameter warning
E6 Servo forced stop warning
E7 Controller forced stop warning
E9 Main circuit off warning
EE SSCNET error warning
Note 1. Deactivate the alarm about 30 minutes of cooling time after removing the cause of occurrence.
2. For confirming the connection to the servo system controller, the alarm may not be reset unless turning the power on twice or
more times.

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9. TROUBLESHOOTING

9.2 Remedies for alarms

When any alarm has occurred, eliminate its cause, ensure safety, then reset the
alarm, and restart operation. Otherwise, injury may occur.
If an absolute position erase alarm (25) occurred, always make home position
CAUTION
setting again. Otherwise, misoperation may occur.
As soon as an alarm occurs, mark Servo-off and power off the main circuit and
control circuit.

POINT
When any of the following alarms has occurred, always remove its cause
and allow about 30 minutes for cooling before resuming operation. If
operation is resumed by switching control circuit power off, then on to reset
the alarm, the servo amplifier and servo motor may become faulty. To
protect the main circuit elements, any of these servo alarms cannot be
deactivated from the servo system controller until the specified time elapses
after its occurrence. Judging the load changing condition until the alarm
occurs, the servo amplifier calculates this specified time automatically.
Regenerative error (30)
Overload 1 (50)
Overload 2 (51)
The alarm can be deactivated by switching power off, then on or by the
error reset command CPU reset from the servo system controller. For
details, refer to section 9.1.

When an alarm occurs, the dynamic brake is operated to stop the servo motor. At this time, the display
indicates the alarm No.
The servo motor comes to a stop. Remove the cause of the alarm in accordance with this section. The MR
Configurator (servo configuration software) may be used to refer to the cause.
Display Name Definition Cause Action
10 Undervoltage Power supply 1. Power supply voltage is low. Check the power supply.
voltage dropped. 2. There was an instantaneous
MR-J2S- B: control circuit power failure of
160VAC or less 60ms or longer.
MR-J2S- B1: 3. Shortage of power supply capacity
83VAC or less caused the power supply voltage to
drop at start, etc.
4. Main voltage has dropped to the
following voltage or less.
MR-J2S- B: 200VDC
MR-J2S- B1: 158VDC
5. Faulty parts in the servo amplifier Change the servo amplifier.
Checking method
Alarm (10) occurs if power is
switched on after CN1A, CN1B
and CN3 connectors are
disconnected.

12 Memory error 1 RAM, memory fault Faulty parts in the servo amplifier Change the servo amplifier.
13 Clock error Printed board fault Checking method
Alarm (any of 12 and 13)
occurs if power is switched on
after disconnection of all cables
but the control circuit power
supply cables.

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9. TROUBLESHOOTING

Display Name Definition Cause Action

15 Memory error 2 EEP-ROM fault 1. Faulty parts in the servo amplifier Change the servo amplifier.
Checking method
Alarm (15) occurs if power is
switched on after disconnection
of all cables but the control
circuit power supply cables.

2. The number of write times to EEP-

ROM exceeded 100,000.
16 Encoder error 1 Communication 1. Encoder connector (CN2) Connect correctly.
error occurred disconnected.
between encoder 2. Encoder fault Change the servo motor.
and servo amplifier. 3. Encoder cable faulty Repair or change the cable.
(Wire breakage or shorted)
17 Board error CPU/parts fault 1. Faulty parts in the servo amplifier Change the servo amplifier.
Checking method
Alarm (17) occurs if power is
switched on after disconnection
of all cable but the control circuit
power supply cable.

The output 2. The wiring of U, V, W is Correctly connect the output terminals U,

terminals U, V, W of disconnected or not connected. V, W of the servo amplifier and the input
the servo amplifier terminals U, V, W of the servo motor.
and the input
terminals U, V, W of
the servo motor are
not connected.
19 Memory error 3 ROM memory fault Faulty parts in the servo amplifier Change the servo amplifier.
Checking method
Alarm (19) occurs if power is
switched on after disconnection
of all cable but the control circuit
power supply cable.

1A Motor Wrong combination Wrong combination of servo Use correct combination.

combination of servo amplifier amplifier and servo motor connected.
error and servo motor.
20 Encoder error 2 Communication 1. Encoder connector (CN2) Connect correctly.
error occurred disconnected.
between encoder 2. Encoder fault Change the servo motor.
and servo amplifier.3. Encoder cable faulty Repair or change the cable.
(Wire breakage or shorted)
Encoder detected 4. Excessive acceleration is occurred 1. Decrease the speed control gain 2.
acceleration error. due to oscillation and others. 2. Decrease the auto tuning response level.
24 Main circuit Ground fault 1. Power input wires and servo motor Connect correctly.
error occurred at the output wires are in contact at
servo motor outputs main circuit terminal block (TE1).
(U,V and W phases) 2. Sheathes of servo motor power Change the cable.
of the servo cables deteriorated, resulting in
amplifier. ground fault.
3. Main circuit of servo amplifier Change the servo amplifier.
failed.
Checking method
Alarm (24) occurs if the servo is
switched on after disconnecting
the U, V, W power cables from
the servo amplifier.
25 Absolute Absolute position 1. Battery voltage low Change the battery.
position erase data in error 2. Battery cable or battery is faulty. Always make home position setting again.
Power was switched 3. Super capacitor of the absolute After leaving the alarm occurring for a few
on for the first time position encoder is not charged. minutes, switch power off, then on again.
in the absolute Always make home position setting again.
position detection
system.
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9. TROUBLESHOOTING

Display Name Definition Cause Action

30 Regenerative Permissible 1. Mismatch between used Set correctly.
error regenerative power regenerative option and
of the built-in parameter No. 2 setting
regenerative 2. Built-in regenerative resistor or Connect correctly.
resistor or regenerative option is not
regenerative option connected.
is exceeded. 3. High-duty operation or continuous 1. Reduce the frequency of positioning.
regenerative operation caused the 2. Use the regenerative option of larger
permissible regenerative power of capacity.
the regenerative option to be 3. Reduce the load.
exceeded.
Checking method
Call the status display and check
the regenerative load ratio.

4. Power supply voltage is abnormal. Review power supply

MR-J2S- B:260VAC or more
MR-J2S- B1:135VAC or more
5. Built-in regenerative resistor or Change the servo amplifier or
regenerative option faulty. regenerative option.
Regenerative 6. Regenerative transistor faulty. Change the servo amplifier.
transistor fault
Checking method
1) The regenerative option has
overheated abnormally.
2) The alarm occurs even after
removal of the built-in
regenerative resistor or
regenerative option.

31 Overspeed Speed has exceeded 1. Small acceleration/deceleration Increase acceleration/deceleration time

the instantaneous time constant caused overshoot to constant.
permissible speed. be large.
2. Servo system is instable to cause 1. Reset servo gain to proper value.
overshoot. 2. If servo gain cannot be set to proper
value.
1) Reduce load inertia moment ratio; or
2) Reexamine acceleration/
deceleration time constant.
3. Encoder faulty. Change the servo motor.
32 Overcurrent Current that flew is 1. Short occurred in servo amplifier Correct the wiring.
higher than the output phases U, V and W.
permissible current 2. Transistor of the servo amplifier Change the servo amplifier.
of the servo faulty.
amplifier. (When Checking method
the alarm (32)
Alarm (32) occurs if power is
occurs, switch the
power OFF and switched on after U,V and W
then ON to reset the are disconnected.
alarm. Then, turn
3. Ground fault occurred in servo Correct the wiring.
on the servo-on.
amplifier output phases U, V and
When the alarm (32)
W.
still occurs at the
4. External noise caused the Take noise suppression measures.
time, the transistor
overcurrent detection circuit to
(IPM IGBT) of the
misoperate.
servo amplifier may
be at fault. Do not
switch the power
OFF/ON repeatedly;
check the transistor
according to the
cause 2 checking
method.)
Current higher than 5. Improper wiring of the Wire the regenerative option correctly.
the permissible regenerative option.
current flew in the
regenerative
transistor.
(MR-J2S-500B only)

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9. TROUBLESHOOTING

Display Name Definition Cause Action

33 Overvoltage Converter bus 1. Regenerative option is not used. Use the regenerative option.
voltage exceeded 2. Though the regenerative option is Make correct setting.
400VDC. used, the parameter No. 2 setting
is " 00 (not used)".
3. Lead of built-in regenerative 1. Change the lead.
resistor or regenerative option is 2. Connect correctly.
open or disconnected.
4. Regenerative transistor faulty. Change the servo amplifier.
5. Wire breakage of built-in 1. For wire breakage of built-in
regenerative resistor or regenerative resistor, change the servo
regenerative option amplifier.
2. For wire breakage of regenerative
option, change the regenerative option.
6. Capacity of built-in regenerative Add regenerative option or increase
resistor or regenerative option is capacity.
insufficient.
7. Power supply voltage high. Review the power supply.
8. Ground fault occurred in servo Correct the wiring.
amplifier output phases U, V and W.
9. The jumper across BUE-SD of the Fit the jumper across BUE-SD.
FR-BU2 brake unit is removed.
34 CRC error Bus cable is faulty 1. Bus cable disconnected. Connect correctly.
2. Bus cable fault Change the cable.
3. Noise entere bus cable. Take measures against noise.
4. Termination connector Connect termination connector.
disconnected.
5. The same No. exists in the servo Set correctly.
amplifier side axis setting.
35 Command Input frequency of 1. Command given is greater than Review operation program.
frequency error command pulse is the maximum speed of the servo
too high. motor.
2. Noise entered bus cable. Take action against noise.
3. Servo system controller failure Change the servo system controller.
36 Transfer error Bus cable or printed 1. Bus cable is disconnected. Connect the connector of the bus cable.
board is faulty 2. Bus cable fault. Change the cable.
3. Printed board is faulty. Change the servo amplifier.
4. Terimination connector Connect termination connector.
disconnected
37 Parameter Parameter setting is 1. Servo amplifier fault caused the Change the servo amplifier.
error wrong. parameter setting to be rewritten.
2. There is a parameter whose value Change the parameter value to within the
was set to outside the setting setting range.
range by the controller.
3. The number of write times to EEP- Change the servo amplifier.
ROM exceeded 100,000 due to
parameter write, etc.
45 Main circuit Main circuit device 1. Servo amplifier faulty. Change the servo amplifier.
device overheat overheat 2. The power supply was turned on The drive method is reviewed.
and off continuously by overloaded
status.
3. Air cooling fan of servo amplifier 1. Change the servo amplifier or cooling
stops. fan.
2. Reduce ambient temperature.

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9. TROUBLESHOOTING

Display Name Definition Cause Action

46 Servo motor Servo motor 1. Ambient temperature of servo Review environment so that ambient
overheat temperature rise motor is over 40 (104 ). temperature is 0 to 40 (32 to 104 ).
actuated the 2. Servo motor is overloaded. 1. Reduce load.
thermal sensor. 2. Review operation pattern.
3. Use servo motor that provides larger
output.
3. Thermal sensor in encoder is Change the servo motor.
faulty.
50 Overload 1 Load exceeded 1. Servo amplifier is used in excess 1. Reduce load.
overload protection of its continuous output current. 2. Review operation pattern.
characteristic of 3. Use servo motor that provides larger
servo amplifier. output.
2. Servo system is instable and 1. Repeat acceleration/
hunting. deceleration to execute auto tuning.
2. Change the auto tuning response
setting.
3. Set auto tuning to OFF and make gain
adjustment manually.
3. Machine struck something. 1. Review operation pattern.
2. Install limit switches.
4. Wrong connection of servo motor. Connect correctly.
Servo amplifier's output terminals
U, V, W do not match servo
motor's input terminals U, V, W.
5. Encoder faulty. Change the servo motor.
Checking method
When the servo motor shaft is
rotated with the servo off,the
cumulative feedback pulses do
not vary in proportion to the
rotary angle of the shaft but the
indication skips or returns midway.

51 Overload 2 Machine collision or 1. Machine struck something. 1. Review operation pattern.

the like caused max. 2. Install limit switches.
For the time of the 2. Wrong connection of servo motor. Connect correctly.
alarm occurrence, Servo amplifier's output terminals
refer to the section U, V, W do not match servo
11.1. motor's input terminals U, V, W.
3. Servo system is instable and 1. Repeat acceleration/deceleration to
hunting. execute auto tuning.
2. Change the auto tuning response
setting.
3. Set auto tuning to OFF and make gain
adjustment manually.
4. Encoder faulty. Change the servo motor.
Checking method
When the servo motor shaft is
rotated with the servo off,the
cumulative feedback pulses do
not vary in proportion to the
rotary angle of the shaft but the
indication skips or returns midway.

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9. TROUBLESHOOTING

Display Name Definition Cause Action

52 (Note) The deviation 1. Acceleration/deceleration time Increase the acceleration/deceleration
Error excessive between the model constant is too small. time constant.
position and the 2. Torque limit value is too small. Increase the torque limit value.
actual servo motor 3. Motor cannot be started due to 1. Review the power supply capacity.
position exceeds the torque shortage caused by power 2. Use servo motor which provides larger
parameter No.31 supply voltage drop. output.
setting value (initial 4. Position control gain 1 (parameter Increase set value and adjust to ensure
value: 2 No.13) value is small. proper operation.
revolutions). 5. Servo motor shaft was rotated by 1. When torque is limited, increase the
external force. limit value.
2. Reduce load.
3. Use servo motor that provides larger
output.
6. Machine struck something. 1. Review operation pattern.
2. Install limit switches.
7. Encoder faulty Change the servo motor.
8. Wrong connection of servo motor. Connect correctly.
Servo amplifier's output terminals
U, V, W do not match servo
motor's input terminals U, V, W.
8E Serial Serial 1. Communication cable fault Repair or change the cable.
communication communication (Open cable or short circuit)
error occurred
error 2. Communication device (e.g. Change the communication device (e.g.
between servo
amplifier and personal computer) faulty personal computer).
communication
device (e.g. personal
computer).
88 Watchdog CPU, parts faulty Fault of parts in servo amplifier Change the servo amplifier.
Checking method
Alarm (88) occurs if power is
switched on after disconnection
of all cable but the control circuit
power supply cable.

Note. The error excessive detection for 2 revolutions is available only when the servo amplifier of software version B1 or later is used.
For the servo amplifier of software version older than B1, an error excessive alarm occurs when the deviation (deviation counter
value) between the instructed position and the actual servo motor position exceeds the parameter No. 1 setting value (initial
value: 8 revolutions).

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9. TROUBLESHOOTING

9.3 Remedies for warnings

POINT
When any of the following alarms has occurred, do not resume operation
by switching power of the servo amplifier OFF/ON repeatedly. The servo
amplifier and servo motor may become faulty. If the power of the servo
amplifier is switched OFF/ON during the alarms, allow more than 30
minutes for cooling before resuming operation.
Excessive regenerative warning (E0)
Overload warning 1 (E1)
If servo forced stop warning (E6), controller forced stop warning (E7) or SSCNET error warning (EE)
occurs, the servo off status is established. If any other warning occurs, operation can be continued but an
alarm may take place or proper operation may not be performed. Eliminate the cause of the warning
according to this section. Use the MR Configurator (servo configuration software) to refer to the cause of
warning.
Display Name Definition Cause Action
92 Open battery Absolute position 1. Battery cable is open. Repair cable or changed.
cable warning detection system battery 2. Battery voltage supplied from the servo Change the battery.
voltage is low. amplifier to the encoder fell to about
3.2V or less.
(Detected with the encoder)
96 Home position Home position return 1. Droop pulses remaining are greater Remove the cause of droop pulse
setting warning could not be made in the than the in-position range setting. occurrence.
precise position. 2. Home position return was executed Reduce creep speed.
during operation command.
3. Creep speed high.
9F Battery warning Voltage of battery for Battery voltage fell to 3.2V or less. Change the battery.
absolute position (Detected with the servo amplifier)
detection system reduced.
E0 Excessive There is a possibility that Regenerative power increased to 85% or 1. Reduce frequency of
regenerative regenerative power may more of permissible regenerative power of positioning.
warning exceed permissible built-in regenerative resistor or 2. Change regenerative option
regenerative power of regenerative option. for the one with larger
built-in regenerative Checking method capacity.
resistor or regenerative Call the status display and check 3. Reduce load.
option. regenerative load ratio.

E1 Overload There is a possibility that Load increased to 85% or more of overload Refer to 50, 51.
warning overload alarm 1 or 2 alarm 1 or 2 occurrence level.
may occur. Cause, checking method
Refer to 50, 51.

E3 Absolute position Absolute position encoder 1. Noise entered the encoder. Take noise suppression
counter warning pulses faulty. measures.
2. Encoder faulty. Change the servo motor.
E4 Parameter Parameter outside Parameter value set from servo system Set it correctly.
warning setting range. controller is outside setting range
E6 Servo forced stop EM1 is off. External forced stop was made valid. Ensure safety and deactivate
warning (EM1 turned off.) forced stop.
E7 Controller forced Forced stop signal was entered into the Ensure safety and deactivate
stop warning servo system controller. forced stop.
E9 Main circuit off Servo-on command was Switch on main circuit power.
warning issued with main circuit
power off.
EE SSCNET error The servo system
warning controller connected is
not SSCNET-compatible.

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