12.2  Alarm Displays
 12.2.2  Troubleshooting Alarms
12-31
A.C51:
Overtravel 
Detected during 
Polarity Detection
The overtravel signal 
was detected during 
polarity detection.
Check the overtravel 
position.
Wire the overtravel sig-
nals. Execute polarity 
detection at a position 
where an overtravel sig-
nal would not be 
detected.
page 4-37
A.C52: 
Polarity Detec-
tion Not Com-
pleted
The servo was turned 
ON under the follow-
ing circumstances.
• Before polarity 
detection was com-
pleted
• Before /P-DET was 
input
– Input the /P-DET signal.
page 5-29
A.C53:
Out of Range of 
Motion for Polar-
ity Detection
The travel distance 
exceeded the setting 
of Pn48E (Polarity 
Detection Range) in 
the middle of detec-
tion.
–
Increase the setting of 
Pn48E (Polarity Detection 
Range). Or, increase the 
setting of Pn481 (Polarity 
Detection Speed Loop 
Gain).
–
A.C54: 
Polarity Detec-
tion Failure 2
An external force was 
applied to the Servo-
motor.
–
Increase the setting of 
Pn495 (Polarity Detection 
Confirmation Force Refer-
ence). Increase the setting 
of Pn498 (Polarity Detec-
tion Allowable Error 
Range). Increasing the 
allowable error will also 
increase the motor tem-
perature.
–
A.C80: 
Encoder Clear 
Error or Multiturn 
Limit Setting Error
A failure occurred in 
the encoder.
–
Turn the power supply to 
the SERVOPACK OFF and 
ON again. If an alarm still 
occurs, the Servomotor or 
linear encoder may be 
faulty. Replace the Servo-
motor or linear encoder.
–
A failure occurred in 
the SERVOPACK.
–
Turn the power supply to 
the SERVOPACK OFF and 
ON again. If an alarm still 
occurs, the SERVOPACK 
may be faulty. Replace the 
SERVOPACK.
–
Continued on next page.
Continued from previous page.
Alarm Number: 
Alarm Name
Possible Cause Confirmation Correction Reference