Mitsubishi Electric MELSERVO MR-J2S- A Instruction Manual page 205

10. TROUBLESHOOTING
Display Name
AL.52 Error excessive
(Note)
AL.8A Serial
communication
time-out error
AL.8E Serial
communication
error
88888 Watchdog
Note. The error excessive detection for 2.5 revolutions is available only when the servo amplifier of software version B0 or later is used.
For the servo amplifier of software version older than B0, an error excessive alarm occurs when the deviation (deviation counter
value) between the instructed position and the actual servo motor position exceeds 10 revolutions.
Definition
The difference 1. Acceleration/deceleration time
between the model constant is too small.
position and the
2. Torque limit value (parameter
actual servomotor
No.28) is too small.
position exceeds 2.5
3. Motor cannot be started due to
rotations.
torque shortage caused by power
(Refer to the
supply voltage drop.
function block
4. Position control gain 1 (parameter
diagram in Section
No.6) value is small.
1.2.)
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.
RS-232C or RS-422 1. Communication cable breakage.
communication
2. Communication cycle longer than
stopped for longer
parameter No. 56 setting.
than the time set in
3. Wrong protocol.
parameter No.56.
Serial 1. Communication cable fault
communication (Open cable or short circuit)
error occurred
2. Communication device (e.g.
between servo
personal computer) faulty
amplifier and
communication
device (e.g. personal
computer).
CPU, parts faulty Fault of parts in servo amplifier
Alarm (88888) occurs if power
is switched on after disconnection
of all cables but the control circuit
power supply cable.
Cause
Checking method
10 - 12
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 communication cable
Set correct value in parameter.
Correct protocol.
Repair or change the cable.
Change the communication device (e.g.
personal computer).
Change servo amplifier.