IS620P User Manual                                                                                            Chapter 6 Troubleshooting
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11.  Er.950: Forward overtravel
Cause: 
 
•
The logic of the DI allocated with function FunIN.14: P-OT (forward drive forbidden) is 
effective.
Cause Conrming Method Corrective Action
The logic of the DI 
allocated with function 
FunIN.14: P-OT 
(forward drive forbidden) 
is effective.
 
•
Check whether a parameter in 
group H03 has been allocated 
with the FunIN14 (P-OT) 
function.
 
•
Check whether the logic of the 
corresponding DI is effective 
though H0B-03 (monitored DI 
states).
Check the running mode. Send a 
reverse reference or rotate the motor 
in the prerequisite of ensuring safety 
to make the logic of the forward 
overshoot switch terminal ineffective.
12. Er.952: Reverse overtravel
Cause: 
 
•
The logic of the DI allocated with function FunIN.15: N-OT (reverse drive forbidden) is 
effective.
Cause Conrming Method Corrective Action
The logic of the DI 
allocated with function 
FunIN.15: N-OT 
(reverse drive forbidden) 
is effective.
 
•
Check whether a parameter in 
group H03 has been allocated 
with the FunIN15: N-OT 
function.
 
•
Check whether the logic of the 
corresponding DI is effective 
though H0B-03 (monitored DI 
states).
Check the running mode. Send a 
reverse reference or rotate the motor 
in the prerequisite of ensuring safety 
to make the logic of the reverse 
overshoot switch terminal ineffective.
13. Er.980: Encoder internal fault
Cause: 
 
•
The encoder algorithm error.
Cause Conrming Method Corrective Action
Encoder internal fault
 
•
The encoder is faulty if the fault 
is still reported after several 
times of power-off and re-
power-on.
Replace the servo motor.