Mitsubishi Electric MELSERVO-J4 Instruction Manual page 94

1. TROUBLESHOOTING FOR SERVO AMPLIFIER (DRIVE UNIT)
Name: USB communication time-out error/serial communication time-out error/Modbus-RTU communication
Alarm No.: 8A
Alarm content
Detail
Detail name
No.
8A.1 USB (1) Communication
communication
time-out
error/serial
communication
time-out error
(2) A communication cable
(3) The servo amplifier is
8A.2 Modbus-RTU (1) Communication
communication
time-out error
(2) A communication cable
(3) The servo amplifier is
time-out error
Communication between the servo amplifier and a personal computer/controller stopped for the specified
time or longer.
An error occurred in USB communication, serial communication (Mitsubishi general-purpose AC servo
protocol), or Modbus-RTU communication.
Cause
Check if a command
commands have not was transmitted from
been transmitted. the personal
computer, etc.
Replace the
was disconnected. communication cable,
and then check the
repeatability.
Replace the servo
malfunctioning. amplifier, and then
check the
repeatability.
Check if a command
commands have not was transmitted from
been transmitted. the controller, etc.
Replace the
was disconnected. communication cable,
and then check the
repeatability.
Replace the servo
malfunctioning. amplifier, and then
check the
repeatability.
Check method Check result
It was not
transmitted.
It was transmitted.
It is not repeatable.
It is repeatable.
It is not repeatable.
It was not
transmitted.
It was transmitted.
It is not repeatable.
It is repeatable.
It is not repeatable.
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Action Target
Transmit a [A]
command. [B]
[WB]
[RJ010]
Check (2).
[GF]
Replace the
communication
cable.
Check (3).
Replace the servo
amplifier.
Transmit a [A]
command.
Check (2).
Replace the
communication
cable.
Check (3).
Replace the servo
amplifier.