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

Page: 364 / 802

11 - 7
11. TROUBLESHOOTING
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. Encoder cable disconnected.
<Check method>
Check the encoder cable connection.
Connect servo amplifier
connector (CN2) and servo
motor encoder connector
correctly. 47
2. Encoder cable faulty
<Check method>
Check if the encoder cable is
disconnected or shorted.
Repair or change the cable.
3. An excessive acceleration occurred
due to oscillation, etc. is detected by
the encoder.
<Check method>
Check if servo motor vibration and
unusual noise, etc. is occurring.
1. Reduce the position loop
gain.
2. Decrease the auto tuning
response level.
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) 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 and
unusual noise, etc. is occurring.
1. Reduce the position loop
gain.
2. Decrease the auto tuning
response level.
2. An error in the detection circuit of the
encoder.
Change the servo motor.