Mitsubishi Electric MELSEC iQ-F Series, User Manual

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9 TROUBLESHOOTING
9.2 Checking with LEDs
133
9
Checking the ERR LED
If the ERR LED flashing
If the ERR LED is flashing, check the following items.
If the ERR LED is turned on
If the ERR LED is turned on, check the following items.
If 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
If the P.RUN LED is turned off, check the status of the ERR LED and take corrective actions. (  Page 133 Checking the
ERR LED)
If the P.RUN LED is turned on, check the following items.
Item to check Cause and action
Write system parameters, CPU parameters, and
program files. Then power on the CPU module
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
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. If 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 PLC, 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.)