If The Alarm Led Lights; If The Led (Power) Of The Power Supply Unit Does Not Light - Panasonic fp2/fp2sh User Manual

FP2/FP2SH
8.2.2

If the ALARM LED Lights

Condition
The system watchdog timer has been activated and the operation of PLC has been
stopped.
Procedure 1
Set the mode selector of CPU from RUN to PROG. mode and turn the power off and
then on.
If the RUN and ALARM LED is turned on again, there is probably an abnormality in the
CPU. Please contact your dealer.
If the ERROR LED is turned on, go to section 8.2.1.
Procedure 2
Set the mode selector from PROG. to RUN mode.
If the ALARM LED is turned on, the program execution time is too long. Check the pro-
gram, referring the following:
Check if instructions such as JP or LOOP are programmed in such a way that a scan
can never finish.
Check that interrupt instructions are executed in succession.
Procedure 3
If there is nothing wrong with programs, there may be a problem with the ambient envi-
ronment.
Check the wirings including the grounding link.
Especially, check if the RS232C wiring is not close to power lines and it has been
shielded.
8.2.3

If the LED (POWER) of the Power Supply Unit Does Not Light

Procedure 1
Check wiring of power supply unit.
Procedure 2
Check if the output of the power supply unit is in the range of the rating.
If the capacity of internally supplied power "5V" is insufficient, investigate different unit
combinations.
Procedure 3
Disconnect the power supply wiring to the other devices if the power supplied to the
power supply unit is shared with them.
If the LED on the power supply unit turn on at this moment, prepare another power sup-
ply for other devices.
Self-Diagnostic Function and Troubleshooting
8.2 Troubleshooting
8 − 7