Mitsubishi Electric MR-J2S-CP Instruction Manual page 239

11. TROUBLESHOOTING
Display Name
AL.51 Overload 2 Machine collision or
the like caused max.
For the time of the
alarm occurrence,
refer to the section
13.1.
AL.52 Error excessive The difference
between the model
position and the
actual servo motor
position exceeds 2.5
rotations. (Refer to
the function block
diagram in section
1.1.1)
AL.61 Operation "1" or more has been
alarm set to auxiliary
function of point
table No. 31.
AL.8A Serial RS-232C or RS-422
communication communication
time-out error stopped for longer
than the time set in
parameter No.23.
AL.8E Serial Serial
communication communication
error error occurred
between servo
amplifier and
communication
device (e.g. personal
computer).
88888 Watchdog CPU, parts faulty
Definition
1. Machine struck something.
2. Wrong connection of servo motor.
Servo amplifier's output terminals
U, V, W do not match servo motor's
input terminals U, V, W.
3. Servo system is instable and
hunting.
4. Encoder faulty.
Checking method
When the servo motor shaft is
rotated with the servo off, the
cumulative feedback pulses do
not vary in proportion to the
rotary angle of the shaft but the
indication skips or returns midway.
1. Acceleration/deceleration time
constant is too small.
2. Internal torque limit 1 (parameter
No.28) is too small.
3. Motor cannot be started due to
torque shortage caused by power
supply voltage drop.
4. Position control gain 1 (parameter
No.7) value is small.
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.
Setting mistake of auxiliary function
of point table No. 31.
1. Communication cable breakage.
2. Communication cycle longer than
parameter No. 23 setting.
3. Wrong protocol.
1. Communication cable fault
(Open cable or short circuit)
2. Communication device (e.g.
personal computer) 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 cables.
Cause
Checking method
11 - 8
Action
1. Review operation pattern.
2. Install limit switches.
Connect correctly.
1. Repeat acceleration/deceleration to
execute auto tuning.
2. Change auto tuning response setting.
3. Set auto tuning to OFF and make gain
adjustment manually.
Change the servo motor.
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.
Set "0" to auxiliary function of point table
No. 31.
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.