Mitsubishi Electric MR-J2S-*B Series Instruction Manual page 138

9. TROUBLESHOOTING
Display Name
52
(Note)
Error excessive
8E Serial
communication
error
88 Watchdog
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 BI, 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).
Definition
The deviation 1. Acceleration/deceleration time
between the model constant is too small.
position and the
2. Torque limit value is too small.
actual servo motor
3. Motor cannot be started due to
position exceeds the
torque shortage caused by power
parameter No.31
supply voltage drop.
setting value (initial
4. Position control gain 1 (parameter
value: 2
No.13) value is small.
revolutions).
5. Servo motor shaft was rotated by
external force.
6. Machine struck something.
7. Encoder faulty
8. Wrong connection of servo motor.
Servo amplifier's output terminals
U, V, W do not match servo
motor's input terminals U, V, W.
Serial
1. Communication cable fault
communication
(Open cable or short circuit)
error occurred
2. Communication device (e.g.
between servo
amplifier and
personal computer) faulty
communication
device (e.g. personal
computer).
CPU, parts faulty Fault of parts in servo amplifier
Alarm (88) occurs if power is
switched on after disconnection
of all cable but the control circuit
power supply cable.
Cause
Checking method
9 - 7
Action
Increase the acceleration/deceleration
time constant.
Increase the torque limit value.
1. Review the power supply capacity.
2. Use servo motor which provides larger
output.
Increase set value and adjust to ensure
proper operation.
1. When torque is limited, increase the
limit value.
2. Reduce load.
3. Use servo motor that provides larger
output.
1. Review operation pattern.
2. Install limit switches.
Change the servo motor.
Connect correctly.
Repair or change the cable.
Change the communication device (e.g.
personal computer).
Change servo amplifier.