Troubleshooting In Bus Connection; Locating Error Positions - Mitsubishi GOT1000 GT15 User Manual

20.2 Troubleshooting in Bus Connection

When connect GOT and PLC CPU with bus connection, and the cause is not clear in "20.3.2 List of Error
Message/System Alarm", execute the following troubleshooting.
Refer to the following for details concerning the bus connection.

20.2.1 Locating error positions

Explanation regarding the method of specifying the error part.
(Please refer to User's Manual of used PLC CPU for details related to the PLC CPU error and special
register.)
(1) How to locate error positions:
(a) Use of peripheral devices
Using the peripheral devices such as GX Developer, check what type of the error occurs on
the PLC CPU and, based on the error message on the PLC CPU, check each module and
cable for installation and earthing statuses.
(b) Error timing
Check the timing of errors.
1) An error occurs when the power is turned on or immediately after the PLC is reset:
2) An error occurs after a specific operation or several seconds:
3) An error occurs when a specific device operates:
(c) Locating the module where an error occurs:
Based on the PLC CPU error codes and special resister information, locate a specific module
where an error occurs.
By the method stated above, correct the sequence program or replace the faulty module with a new
one, and check whether the error occurs.
If the error continues to occur, it may have another cause.
Referring to 20.2.2 "Further locating error positions", locate the error position further.
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20.2 Troubleshooting in Bus Connection
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20.2.1 Locating error positions
•GOT1000 Series Connection Manual (Mitsubishi Products) for GT Works3
•GOT1000 Series Connection Manual for GT Designer2/GT Works2
The error may be detected by the initial processing of the PLC CPU.
In this case, because the faulty module may not be identified, use only an END
instruction for the sequence program and remove the modules one by one until the error
does not occur.
When the error is eliminated after a specific module has been removed, the module may
be causing the error.
The error may occur in the sequence program. Check the error step where the error may
occur and the sequence program in that step.
The sequence program can be diagnosed throughout by merely using an END
instruction for the sequence program.
The mis-operation may be caused by noise.
Check that any signal line such as bus cable is not laid out too close to the operating
device. If the line is too close to the device, separate the line 100 mm or more from the
device.