Error Led [On/Flashing/Off] - Mitsubishi FX3U SERIES User Manual

FX Series Programmable Controllers
3U
User's Manual - Hardware Edition

14.5.3 ERROR LED [on/flashing/off]

State of
LED
A watchdog timer error may have
On occurred, or the hardware of the PLC
may be damaged.
One of the following errors has
occurred in the PLC.
• Parameter error
Flashing
• Syntax error
• Ladder error
No errors that stop the PLC have
Off
occurred.
14 Test Operation, Adjustment, Maintenance and Troubleshooting
State of PLC
1) Stop the PLC, and re-apply power.
2) Remove the PLC and supply power to it from another power
3) If the ERROR LED does not go off even after the measures
Perform
programming tool.
For the remedies, refer to Section 14.6 "Judgment by Error
Codes and Representation of Error Codes".
If the operations of the PLC are abnormal, perform PLC
diagnosis and program check with the programming tool.
An I/O error, Comms.error or Runtime error may have occurred.
Remedies
If ERROR LED goes off, a watchdog timer error may have
occurred. Take any of the following measures.
- Review the program.
The maximum value (D8012) of the scan time should not
exceed the setting (D8000) of the watchdog timer.
- 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 (duty of 50%) input to
the high-speed counter does not exceed the specified
range.
- Add the WDT instructions.
Add some WDT instructions to the program, and reset the
watchdog timer several times in one scan.
- Change the setting of the watchdog timer.
Change the watchdog timer setting (D8000) in the program
so that the setting is larger than the maximum value of the
scan time (D8012).
supply on a desk.
If the ERROR LED goes off, noise may have affected the
PLC. Take the following measures.
- Check the ground wiring, and reexamine the wiring route
and installation location.
- Fit a noise filter onto the power supply line.
stated in (1) and (2) are taken, consult your local Mitsubishi
Electric distributer.
PLC diagnosis and
14.5 Troubleshooting with LEDs
program check with the
251
11
12
13
14
15
16
17
18
19
20