Specific Example Of Troubleshooting - Mitsubishi Electric GT11 User Manual

18.3.3 Specific example of troubleshooting

Taking the following system as an example, troubleshooting is shown when PLC CPU error occurred. (When
QnASCPU and the extension base unit are used)
Extension cable
(Obtain the status of the error and the location where the error occurs.)
Disconnect the bus-connection cable from the GOT 1) at OUT side
The bus-connection cable connecting the GOT 1) to the GOT 2) is judged faulty.
PLC
(main base unit)
PLC
(extension base unit)
Start
Check the error code/step appearing on the PLC CPU.
The SP. UNIT DOWN message appears on PLC CPU.
Turn off the power of the GOT.
Turn off the power of the PLC.
Replace the faulty PLC CPU with a new one.
Turn on the power of the PLC.
Turn on the power of the GOT.
The error occurs further (not on PLC CPU).
Turn off the power of the GOT.
Turn off the power of the PLC.
Disconnect the bus-connection cable from the GOT 2) at IN side
(to further locate the error positions).
Turn on the power of the PLC.
Turn on the power of the GOT.
The error occurs further
(not on the GOT 2) (bus connection unit).
Turn off the power of the GOT.
Turn off the power of the PLC.
(to further locate the error positions).
Turn on the power of the PLC.
Turn on the power of the GOT.
The error will not occur.
Replace the faulty bus-connection cable with a new one.
End
GOT 1) GOT 2)
Bus connection Bus connection
cable cable
18.3 Troubleshooting in Bus Connection
18.3.3 Specific example of troubleshooting
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