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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
38 Error Check Method and Error Code List
38.1 States and Colors of LEDs PLC Operation Status
31
FNC275-FNC279
Data
Transfer 3
32
FNC280-FNC289
High Speed
Processing 2
33
FNC290-FNC299
Extension File
Register
34
FNC300-FNC305
FX
3U
-CF-ADP
35
SFC•STL
Programming
36
Interrupt
Function
37
Special Device
38
Error Code
A
Version Up
Information
B
Execution Times
38.1.3 BATT (BAT) LED [lit or unlit] [FX3U/FX3UC]
38.1.4 ALM LED [lit or unlit] [FX3G]
This LED is valid when the optional battery is installed and the battery mode is selected using a parameter.
38.1.5 ERROR (ERR) LED [lit, flickering or unlit] [FX3G/FX3U/FX3UC]
LED status PLC status Action
Lit The battery voltage is low.
Replace the battery as soon as possible.
(Refer to FX
3U/FX3UC Hardware edition.)
Unlit
The battery voltage exceeds the value set in
D8006.
The battery is normal.
LED status PLC status Action
Lit The battery voltage is low.
Replace the battery as soon as possible.
(Refer to FX
3G Hardware edition.)
Unlit
The battery voltage exceeds the value set in
D8006.
The battery is normal.
LED status PLC status Action
Lit
A watchdog timer error has occurred, or
the hardware of the PLC may be
damaged.
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.
Flickering
Either of the following errors occur in PLC:
• Parameter error
• Syntax error
• Circuit error
Execute PLC diagnostics and program check by programming tool.
For instructions, refer to Section 38.4.
Unlit Error which stops PLC has not occurred.
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.