User`s manual

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MELSEC

11 TROUBLESHOOTING

This chapter describes how to determine the cause of trouble that may occur during

system construction as well as appropriate corrective actions.

11.1 When Performing Troubleshooting

Ideally occurrence of trouble should be kept to a minimum in order to startup the

system effectively. However, once an error occurs, it is important that we identify the

cause as quickly as possible.

The followings are the three basic points that must be kept in mind when performing

troubleshooting.

(1) Visual check

Check the following points.

1) Movement of the external device (status when stopped or during operation)

2) On/off status of power supply

3) Wiring condition (cable)

4) LED display status (power supply display LED)

5) Checks whether the PC is one suitable for the operating environment

After checking 1) through 5), connect the external device and check the

operation of the user program.

(2) Confirming the error

Examine how the error status changes by the following operation.

1) Change the input status and check if the change can be read correctly using

the test program.

2) Repeat on/off of output and check if the status of the external device changes

accordingly.

(3) Narrowing the range

Based on the steps 1) and 2) above, deduce the range of error location as one of

the following.

1) PC side or external device side

2) PC main body or board

3) Cable

4) User program