Mitsubishi Electric MR-E A Series Instruction Manual page 161

10. TROUBLESHOOTING
Display
AL.51 Overload 2
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AL.52 Error excessive The droop pulse
AL.8A Serial
communication
time-out error
AL.8E Serial
communication
error
88888 Watchdog
Name Definition
Machine collision or
the like caused max.
output current to
flow successively for
several seconds.
Servo motor locked:
1s or more
During rotation:
2.5s or more
value of the
deviation counter
exceeded 2.5
rotations.
RS-232C or RS-422
communication
stopped for longer
than the time set in
parameter No.56.
Serial
communication
error occurred
between servo
amplifier and
communication
device (e.g. personal
computer).
CPU, parts faulty
Cause
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
10 - 10
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.
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.