10  Troubleshooting
10.1.2  Troubleshooting of Alarms
10-18
A.C92:
Encoder 
Communications 
Timer Error
Noise interference occurred on 
the I/O signal line from the 
encoder.
−
Take countermeasures against noise 
for the encoder wiring.
Excessive vibration and shocks 
were applied to the encoder.
Check the operating environment.
Reduce the machine vibration or 
correctly install the servomotor.
An encoder fault occurred. −
Turn the power supply OFF and 
then ON again. If the alarm still 
occurs, the servomotor may be 
faulty. Replace the servomotor.
A fault occurred in the SERVO-
PACK.
−
Turn the power supply OFF and 
then ON again. If the alarm still 
occurs, the SERVOPACK may be 
faulty. Replace the SERVOPACK.
A.CA0:
Encoder Parameter 
Error
An encoder fault occurred. −
Turn the power supply OFF and 
then ON again. If the alarm still 
occurs, the servomotor may be 
faulty. Replace the servomotor.
A fault occurred in the SERVO-
PACK.
−
Turn the power supply OFF and 
then ON again. If the alarm still 
occurs, the SERVOPACK may be 
faulty. Replace the SERVOPACK.
A.Cb0:
Encoder Echoback 
Error
The wiring and contact for 
encoder cable are incorrect.
Check the wiring. Correct the wiring.
Noise interference occurred due 
to incorrect cable specifications 
of encoder cable.
−
Use tinned annealed copper 
shielded twisted-pair or screened 
unshielded twisted-pair cable with a 
core of at least 0.12 mm
2
.
Noise interference occurred 
because the wiring distance for 
the encoder cable is too long.
−
The wiring distance must be 50 m 
max.
The FG potential varies because 
of influence from machines on 
the servomotor side, such as the 
welder.
Check the cable layout for encoder 
cable.
Properly ground the machines to 
separate from encoder FG.
Excessive vibration and shocks 
were applied to the encoder.
Check the operating environment.
Reduce the machine vibration or 
correctly install the servomotor.
An encoder fault occurred. −
Turn the power supply OFF and 
then ON again. If the alarm still 
occurs, the servomotor may be 
faulty. Replace the servomotor.
A fault occurred in the SERVO-
PACK.
−
Turn the power supply OFF and 
then ON again. If the alarm still 
occurs, the SERVOPACK may be 
faulty. Replace the SERVOPACK.
A.CC0:
Multiturn Limit 
Disagreement
The multiturn limit value of the 
encoder is different from that of 
the SERVOPACK. Or, the multi-
turn limit value of the SERVO-
PACK has been changed.
Check the value of the Pn205 of the 
SERVOPACK.
Execute Fn013 at the occurrence of 
alarm.
A fault occurred in the SERVO-
PACK.
−
Turn the power supply OFF and 
then ON again. If the alarm still 
occurs, the SERVOPACK may be 
faulty. Replace the SERVOPACK.
(cont’d)
Alarm Number:
Alarm Name
(Alarm Description)
Cause Investigative Actions Corrective Actions