10 TROUBLESHOOTING

10.3.1 Troubleshooting when "RUN" LED is turned OFF

MELSEC-Q

Symptom

 

Cause

 

 

Corrective action

MC

 

A transmission setting

Set the switch by GX Developer correctly and

 

 

 

switch is set to an

 

after writing to the CPU reset the CPU.

 

 

 

unusable position.

 

 

 

 

 

 

 

• Remove the cause of the CPU error and reset

 

 

 

 

 

the CPU.

 

 

• PLC CPU error.

 

Note

 

 

 

 

• During the Q series C24 and external device

 

 

 

 

 

 

 

 

 

 

loopback test, the minimum parameters file

 

 

 

 

 

must be written to the CPU beforehand.

 

• The Q series C24

 

 

Calculate the 5 V current drain of each installed

 

 

 

 

module. If the current capacity is insufficient,

 

"RUN" LED turned off.

 

 

 

 

 

 

 

check power module selection.

 

 

• Power module 5 V

 

 

 

 

Note

 

 

 

 

current capacity is

 

 

 

 

 

 

• Whether or not the current capacity is

 

 

 

insufficient.

 

 

 

 

 

insufficient can be checked by disconnecting

 

 

 

 

 

 

 

 

 

 

the expansion base and installing only the Q

 

 

 

 

 

series C24 to the basic base.

 

 

Extraneous noise

Check if the shield wire is 2-point ground.

 

 

 

caused the Q series

• When ground is used with other devices,

 

 

 

C24 to abnormal

 

ground the Q series C24 independently.

 

 

 

operation.

 

 

 

 

 

 

 

 

 

 

 

Bidirectional Non procedure

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