Error (Err) Led [Lit, Flickering Or Unlit]; Fx 3Uc ] - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
38.1.5 ERROR (ERR) LED [lit, flickering or unlit] [FX
LED status
Lit
Flickering
Unlit
934
PLC status
A watchdog timer error has occurred, or
the hardware of the PLC may be
damaged.
Either of the following errors occur in PLC:
• Parameter error
• Syntax error
• Circuit error
Error which stops PLC has not occurred.
38 Error Check Method and Error Code List
38.1 States and Colors of LEDs PLC Operation Status
/FX /FX ]
3G 3U 3UC
Action
1) Change the PLC mode to STOP, and turn ON the PLC
power again.
When the ERROR (ERR) LED is off, a watchdog timer
error occurred. Take one of the following actions:
- Review the program, and make sure that the
maximum value (D8012) of the scan time is not larger
than the set value (D8000) of the watchdog timer.
- Make sure that an input used for input interrupt or
pulse catch does not abnormally turn ON and OFF
several times in one scan time.
- Make sure that the frequency of the pulse (duty: 50%)
input to a high speed counter is within the
specifications range.
- Adding WDT instruction
Use two or more WDT instructions in a program so
that the watchdog timer is reset several times in one
scan time.
- Change the set value of the watchdog timer
Change the set value (D8000) of the watchdog timer in
a program so that it is larger than the maximum value
(D8012) of the scan time.
2) Remove the PLC, and connect another power supply to
the PLC.
If the ERROR (ERR) LED is off, the cause of the error
may be noise. Examine the following action:
- Check the wiring for grounding, and then review the
wiring route and installation location.
- Add a noise filter in the power line.
3) If the ERROR (ERR) LED is not off even after the step 1)
or 2), consult a Mitsubishi Electric Distributor.
Execute PLC diagnostics
programming tool.
For instructions, refer to Section 38.4.
If PLC operation is a failure, execute the PLC diagnostics or
program check by programming tool.
An I/O configuration error, serial communication error, or
operation error may occur.
and program check by