Mitsubishi Electric MELSEC iQ-F FX5UC Series, User Manual

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254
15 TROUBLESHOOTING
15.2 Checking with LEDs
Checking the ERR LED
When the ERR LED flashing
When the ERR LED is flashing, check the following items.
When the ERR LED turns on
When the ERR LED turns on, check the following items.
When the ERR LED still does not turn off even after the items shown above are checked, there may be a hardware issue.
Consult your local Mitsubishi Electric representative.
Checking the P.RUN LED
When the P.RUN LED turns off, check the status of the ERR LED and take corrective actions. (  Page 254 Checking the
ERR LED)
When the P.RUN LED turns on, check the following items.
Item to check Cause and action
Write system parameters, CPU parameters, and
program files, and turn on the power supply again. Programs or parameters are not written or damaged. Since a CPU module with the factory default
setting has no programs, the ERR LED flashes.
Set the CPU module to the STOP status and turn on
the power supply again. When the ERR LED turns off, a watchdog timer error has probably occurred. Take any of the following
measures.
• Review the program and avoid the maximum value (SD524, SD525) of the scan time exceeding the
scan time monitoring time setting value set by the parameter.
• Check that the input used for input interruption or pulse catch is not being abnormally turned on and
off in one scan.
• Check that the frequency of the pulse input to the high-speed counter is within the specified range.
• Add some WDT instructions to the program and reset the watchdog timer several times in one scan.
Item to check Cause and action
Provide a different power supply to the CPU module. When the ERR LED turns off, noise may have affected the module. Consider taking the following
measures.
• Check the ground wiring, and reexamine the wiring route and installation location.
• Fit a noise filter onto the power supply line.
Cause CPU module status Action
After writing to programmable controller, the CPU
module was set to RUN without resetting. Stopped Reset the CPU module or turn off and on the power
supply, and then set the CPU module to RUN.
The operating status of the CPU module was
changed to RUN or PAUSE at the time of online
program change. Operating status before the change Wait until P.RUN LED stops flashing. (When the
online program change is completed, P.RUN LED
automatically stops flashing. After that, the
operation status is switched.)