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PLC User's Manual - Positioning Control Edition
Built-in Positioning Functions
13 Troubleshooting
13.1 LED Indicator Lamp Check
B - 171
A
Common Items
B
Built-in
Positioning
Functions
Apx.
Example
Connection
13.1.2 RUN Indicator Lamp (Statuses: ON, OFF) [FX3G/FX3U/FX3UC]
13.1.3 BATT Indicator Lamp (Statuses: ON, OFF) [FX3U/FX3UC]
13.1.4 ALM Indicator Lamp (Statuses: ON, OFF) [FX3G]
This LED is valid when the optional battery is installed and the battery mode is selected using a parameter.
13.1.5 ERROR indicator lamp (Statuses: ON, flashing, OFF) [FX3G/FX3U/FX3UC]
Lamp
status
Status of PLC Troubleshooting
ON
The sequence program is being
executed.
The RUN indicator lamp indicates the operation status of the PLC.
Note that the RUN indicator lamp will go out depending on the status
of the ERROR indicator lamp (refer to Subsection 13.1.4).
OFF
Execution of the sequence program is
stopped.
Lamp
status
Status of PLC Troubleshooting
ON
The voltage of the battery is too low. Immediately replace the battery (refer to the manual of the PLC).
OFF
The battery supplies enough voltage as
specified by D8006.
The PLC has no problems.
Lamp
status
Status of PLC Troubleshooting
ON
The voltage of the battery is too low. Immediately replace the battery (refer to the manual of the PLC).
OFF
The battery supplies enough voltage as
specified by D8006.
The PLC has no problems.
Lamp
status
Status of PLC Troubleshooting
ON
A watchdog timer error may have
been detected, or the hardware of the
PLC may be damaged.
1) Stop the PLC, and then turn the power ON again. If the
ERROR (ERR) indicator lamp goes out, check to see if a
watchdog timer error has been detected, and take one of the
following measures.
- Review the program.
The maximum value of the scanning time (D8012) should
not be larger than the set value of the watchdog timer
(D8000).
- The interrupt input and the pulse catch input should not be
turned on and off too frequently during 1 scan time.
- The frequency of the pulse input to the high-speed counter
should not exceed the specified range (duty:50%)
- Add several WDT instructions.
Set several WDT instructions in the program so that the
watchdog timer can be reset several times during 1 scan
time.
- Change the set value of the watchdog timer.
Using the program, change the set value of the watchdog
timer (D8000) so that the set value of the watchdog timer
(D8000) can be larger than the maximum value of the
scanning time (D8012).
2) Remove the PLC, and put it on a workbench. Supply another
source of power to the PLC.
If the ERROR (ERR) indicator lamp does not light, the cause
of the problem may be noise. In this case, take the following
measures.
- Check the grounding line, and change the wiring route and
the installation place.
- Adopt a noise filter for the power supply line.
3) If measures 1) and 2) do not turn the ERROR indicator lamp
OFF, please contact the nearest
Mitsubishi Electric
distributor
office.