Mitsubishi Electric MR-J2S-A Instruction Manual page 209

10. 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
12.1.
AL.52 Error excessive The difference
between the model
(Note)
position and the
actual servo motor
position exceeds 2.5
rotations.
(Refer to the
function block
diagram in section
1.2)
AL.8A Serial RS-232C or RS-422
communication communication
time-out error stopped for longer
than the time set in
parameter No.56.
AL.8E Serial Serial
communication communication
error error occurred
between servo
amplifier and
communication
device (e.g. personal
computer).
88888 Watchdog CPU, parts faulty
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
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. Torque limit value (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.6) 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.
1. Communication cable breakage.
2. Communication cycle longer than
parameter No. 56 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
Checking method
Alarm (88888) occurs if power
is switched on after disconnection
of all cables but the control circuit
power supply cable.
10 - 12
WWW.NNC.IR
Cause
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.
Repair or change the communication cable
Set correct value in parameter.
Correct protocol.
Repair or change the cable.
Change the communication device (e.g.
personal computer).
Change the servo amplifier.
Action