Troubleshooting By Symptom; The Run Led Flashes Or Turns Off; The Err Led Turns On; The Alm Led Turns On Or Flashes - Mitsubishi Electric MELSEC iQ-R Series User Manual

3.3

Troubleshooting by Symptom

The RUN LED flashes or turns off

When flashing
Check item
Check whether the module is in offset/gain setting
mode.
When it is off
Check item
Check whether the power is supplied.
Check whether the capacity of the power supply module is enough.
Check whether the module is mounted properly.
Cases other than the above

The ERR LED turns on

Check item
Check whether any error has occurred.

The ALM LED turns on or flashes

When it is on
Check item
Check whether any alert has been issued.
When flashing
Check item
Check whether disconnection of a thermocouple or compensation lead wire is
detected in the thermocouple input module.
Check whether disconnection is detected in the RTD input module.
3 TROUBLESHOOTING
80
3.3 Troubleshooting by Symptom
Cause
The programmable controller has been powered
off and on, or the CPU module has been reset
when the operation mode is set to offset/gain
setting mode in the module parameter setting of
the engineering tool.
The G(P).OFFGAN instruction has been executed
with the mode switched to offset/gain setting mode.
The value in the mode switching setting has been
changed and the mode has been switched to
offset/gain setting mode.
Action
Check that the supply voltage of the power supply module is within the rated
range.
Calculate the current consumption of mounted modules, such as the CPU
module, I/O modules, and intelligent function modules to check that the power
capacity is enough.
Check the mounting state of the module.
A watchdog timer error may have occurred. Reset the CPU module, and
check that the RUN LED turns on. If the RUN LED still remains off, the
possible cause is a failure of the module. Please consult your local Mitsubishi
representative.
Action
Check 'Latest error code' (Un\G0) and take actions described in the list of
error codes.
Page 83 List of Error Codes
Action
Check Alert output flag (Process alarm upper limit), Alert output flag (Process
alarm lower limit), Alert output flag (Rate alarm upper limit), and Alert output
flag (Rate alarm lower limit).
Take actions described in the list of alarm codes.
Page 87 List of Alarm Codes
Action
Eliminate the cause of disconnection, by replacing the thermocouple or
compensation lead wire for instance, and check 'CH1 Measured temperature
value' (Un\G400).
Eliminate the cause of disconnection, by replacing the resistance temperature
detector for instance, and check 'CH1 Measured temperature value'
(Un\G400).
Action
In the module parameter setting of the engineering
tool, set the operation mode to normal mode and
power off and on the programmable controller, or
reset the CPU module.
Review the program that uses the G(P).OFFGAN
instruction to check whether the mode has been
switched erroneously.
Review the program that uses the mode switching
setting to check whether the mode has been
switched erroneously.