15 - 78
MELSEC-Q
15 TROUBLESHOOTING
LED indicator
of servo
amplifier
Classifica
tion of
errors
Error
code
IFU DRU
Error name Description Cause
Interface unit connection fault.
Interface unit failure.
2022
FA.1C
—
Base unit bus
error 1
There is error in communication
between interface unit and drive
unit.
Base unit failure.
Drive unit connection fault.
Drive unit failure.
2023
FA.1D
—
Base unit bus
error 2
There is error in communication
between interface unit and drive
unit.
Base unit failure.
Drive unit connection fault.
Base unit failure.
2024
FA.1E
—
Servo amplifier
mounting error
Drive unit came off the base unit
after initialization.
Faulty parts in servo amplifier.
The encoder connecter is
disconnected.
Encoder fault.
2020
—
@A.20#
Encoder error 2
Communication error occurred
between encoder and drive unit.
Encoder cable faulty. (Wire
breakage or shorted)
Power input wires and servo motor
output wires are in contact at CNP2.
Sheathes of servo motor power
cables deteriorated, resulting in
ground fault.
2024
—
@A.24#
Motor output
side ground
fault
Servomotor output (U, V, W
phase) ground fault.
Main circuit of drive unit failed.
Battery unit voltage low.
Absolute position data in error.
Battery cable or battery fault.
Servo
amplifier
errors
2025
—
@A.25#
Absolute
position lost
Power was switched on for the
first time in the absolute position
detection system.
Super capacitor of the absolute
position encoder is not charged.