Mitsubishi Electric Melservo-J3 Series MR-J3-B, Instruction Manual

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16 - 108
16. INDEXER POSITIONING OPERATION
Display Name Definition Cause Action
(Note 2)
Alarm
detailed
information
A20 Encoder error
2 (during
runtime)
Communication
error occurred
between
encoder and
servo amplifier.
1. The encoder cable was disconnected.
<Check method>
Check the encoder cable connection.
Connect the servo
amplifier connector
(CN2) and the servo
motor encoder
connector correctly. 47
2. Encoder cable is faulty.
<Check method>
Check if the encoder cable is disconnected or
shorted.
Repair or replace the
cable.
3. An excessive acceleration occurred due to
oscillation, etc. is detected by the encoder.
<Check method>
Check if servo motor vibration or unusual noise, etc.
is occurring.
1. Reduce the position
loop gain.
2. Decrease the auto
tuning response
setting.
8
4. Encoder fault. Change the servo
motor.
5. External noise caused a communication error.
<Check method>
1. Check that the encoder cable and the power
cable run in parallel.
2. Check if the environment is affected by the noise
of surrounding electromagnetic valve, magnetic
contactor, relay, etc.
3. Check the servo amplifier and servo motor for
grounding.
4. Check if there is a factor causing surrounding
static electricity.
5. Check shield procedure of the encoder cable.
Take the grounding and
noise reduction
techniques.
A21
Encoder error
3 (during
runtime)) An error
occurred in
encoder.
1. An excessive acceleration occurred due to
oscillation, etc. is detected by the encoder.
<Check method>
Check if servo motor vibration or unusual noise, etc.
is occurring.
1. Reduce the position
loop gain.
2. Decrease the auto
tuning response
setting.
2. A fault in the detection circuit of the encoder. Change the servo
motor.