Narrowing The Possible Error Positions - Mitsubishi Electric GOT2000 Series User Manual

10.2.2

Narrowing the possible error positions

If the system cannot be restored even though the module with an error is replaced, another module may cause the error.
Disconnect the extension cables and bus connection cables in order, starting from the module at the end of the system, and
check for the error.
The module, extension cable, or bus connection cable disconnected immediately before the error does not occur is
considered to cause the error.
The following shows examples of narrowing possible error positions. (When QnASCPU and an extension base unit are
used)
Example 1:
Turn off the power of the GOT.
Turn off the power of the PLC.
Disconnect the bus connection cable
(IN side) from the GOT located at the final stage.
Turn on the power of the PLC.
Turn on the power of the GOT.
If an error does not occur, the GOT
located at the final stage may be faulty.
Repeat examples 1 and 2 above to identify the error position.
Precautions for narrowing the possible error positions
When disconnecting the modules from the extension base unit in order, setting only the END
instruction in the sequence program eliminates errors arising from the sequence program.
Therefore, you can check the error occurrence easily.
When the error does not occur frequently, take time to check the error occurrence with the
modules disconnected.
This check is effective to identify a noise invading route when the malfunction is caused by noise.
POINT POINT POINT
Example 2:
Turn off the power of the GOT.
Turn off the power of the PLC.
Disconnect the bus connection cable (OUT side) from
the GOT located at one stage before the final stage.
Turn on the power of the PLC.
Turn on the power of the GOT.
If an error does not occur, the GOT located at
the final stage and the bus connection cable
connected to that GOT may be faulty.
10.2 Troubleshooting for the Bus Connection
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