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Troubleshooting For The Bus Connection; Identifying The Error Position - Mitsubishi Electric GOT2000 Series User Manual

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12.2 Troubleshooting for the Bus Connection

If an error occurs in the bus connection between the GOT and the PLC CPU and the cause is not clear with the system
alarm, perform the troubleshooting described in this section.
For the details of the system alarm, refer to the following.
For the details of the bus connection, refer to the following.

Identifying the error position

This section explains how to identify the error position.
For the details of the PLC CPU error and special register, refer to the User's Manual of the PLC CPU used.
■1. How to identify the error position
Identify the error position, modify the sequence program or replace the module where the error occurs, and check
whether the error occurs again.
If the error occurs again, other causes are considered.
Refer to the following to narrow possible error positions.
(1) Checking the error in the PLC
Step 1.
Check the type of the error detected in the PLC using GX Works2 or others.
Step 2.
Check each module and the installation and grounding status of the cables according to the error
message on the PLC CPU.
(2) Checking the error occurrence timing
Check the timing of the error occurrence.
An error occurs when the power is turned on or immediately after the PLC is reset.
The error may be detected in the initial process of the PLC CPU.
In this case, since the faulty module cannot be usually identified, set only the END instruction in the sequence
program and remove the modules one by one.
When the error is eliminated after a specific module has been removed, the module may have caused the error.
An error occurs after or several seconds after a specific operation.
The error may occur in the sequence program.
Check the error step where the error may occur and the sequence program in the step.
You can determine whether the whole sequence program has a problem by setting only the END instruction in
the sequence program.
An error occurs when a specific device operates.
A malfunction caused by noise is considered.
Check if any signal line such as a bus connection cable is not installed close to the operating device.
If the line is close to the device, keep a distance of 100 mm or more between the line and the device.
(3) Identifying the module where an error occurs
Identify the module where an error occurs using the PLC CPU error codes and special resister information.
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12.2 Troubleshooting for the Bus Connection
GOT2000 Series User's Manual (Utility)
GOT2000 Series Connection Manual For GT Works3 Version1 compatible for a controller used
Refer to the User's Manual of the PLC CPU you use.


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