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9 TROUBLESHOOTING
9.3 Troubleshooting using the engineering tool
121
9
Checking the ERR LED
If the ERR LED flashes
If the ERR LED is turned on, 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 121 Checking the
ERR LED)
9.3 Troubleshooting using the engineering tool
Check the error or history using the engineering tool, and identify the error cause. More detailed information on the error as
well as the error cause and action to be taken can be checked by using the engineering tool.
The engineering tool has the following functions for troubleshooting.
For details on each function, refer to the following.
GX Works3 Operating Manual
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.
Item to check Cause and action
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.
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.
Function Description
Module diagnostics (CPU Diagnostics) This function diagnoses the module. (The current error and its details can be checked.)