Mitsubishi MELSEC iQ-F FX5UC, User Manual

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128
9 TROUBLESHOOTING
9.2 Checking with LEDs
Checking the ERR LED
If the ERR LED flashes
If the ERR LED flashes, check the following items.
If the ERR LED turns on
If the ERR LED turns 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 128 Checking the
ERR LED)
Item to check Cause and action
Write system parameters, CPU parameters, and
program files, and turn on the power supply again. Programs or parameters may 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
setting value of the scan time monitoring time which was set with parameters.
• 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.