When The "Alive" Led Does Not Turn On Or Turns Off - Mitsubishi MELSEC User Manual

12
TROUBLESHOOTING

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
Replace the power supply module and
check that the "POWER" LED is on.
Hardware failure of the following modules
1) CPU module
2) Base unit
3) CC-Link Safety master module
4) Network module (if mounted)
Execute operation check sequentially from
the minimum system.
For the module that does not operate, please
consult your local Mitsubishi service center or
representative, explaining a detailed
description of the problem.
power-ON of the programmable controller.
The "ALIVE" LED does not turn on.
How is the "POWER"
LED of the power supply
module?
On
Is RUN/STOP/RESET
switch of the CPU
module set at RESET
position?
STOP/RUN position
Can the CPU module
communicate with GX
Developer?
Impossible
How is the "ALIVE" LED
of the CPU module?
Off
12.2.4 When the "ALIVE" LED does not turn on or turns off
Off
Check the wiring and turn on all power
supplies.
RESET position
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 service
center or representative, explaining a
detailed description of the problem.
Possible
Execute PLC diagnostics and
troubleshooting according to its result.
On
Hardware failure of the power supply module
before replacement is suspected.
12.2 Troubleshooting Flowchart
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