Mitsubishi Electronics QSPCU Manual De Usuario

12

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12

12.2.4  When the "ALIVE" LED does not turn on or turns off

This section describes the troubleshooting for when the "ALIVE" LED of the CPU module 
does not turn on at power-ON of the programmable controller or when the "ALIVE" LED 
turns off during operation.

(1) Flowchart for when the "ALIVE" LED of the CPU module does not turn on at 

power-ON of the programmable controller.

The "ALIVE" LED does not turn on.

Set the RUN/STOP/RESET switch to the 
STOP position. If it is impossible to set it at 
STOP position, failure of the CPU module is 
suspected.
Please consult your local Mitsubishi 
representative, explaining a detailed 
description of the problem.

RESET position

Possible

STOP/RUN position

Impossible

How is the "ALIVE" LED 

of the CPU module?

How is the "POWER" 

LED of the power supply 

module?

Off

Off

On

On

Check the wiring and turn on all power 
supplies.

Execute PLC diagnostics and 
troubleshooting according to its result.

Hardware failure of the power supply module 
before replacement is suspected.

Hardware failure of the following modules
 1) CPU module
 2) Base unit
 3) Intelligent function module (if mounted)
Execute operation check sequentially from 
the minimum system.
For the module that does not operate, please 
consult your local Mitsubishi representative, 
explaining a detailed description of the 
problem.

Replace the power supply module and 
check that the "POWER" LED is on.

Can the CPU module 

communicate with GX 

Developer?

Is RUN/STOP/RESET 

switch of the CPU 

module set at RESET 

position?