FPΣ User's Manual
11.4 ERROR/ALARM LED is ON
265
11.4 ERROR/ALARM LED is ON
If the ERROR/ALARM LED is on, the system watchdog timer has been activated and the
operation of the PLC has been stopped. There are two ways to remedy the problem:
• Set the mode selector of the PLC from RUN to PROG mode and turn the power off
and then on.
- If the ERROR/ALARM LED turns on again, there is probably an abnormality in the
CPU. Please contact your dealer.
- Check if the ERROR/ALARM LED is flashing. See "ERROR/ALARM LED is
Flashing" on page
264.
• Set the mode selector from PROG to RUN mode. If the ERROR/ALARM LED turns
on, the program execution time is too long.
- Check if instructions such as JP or LOOP are programmed in such a way that a
scan can never finish.
- Make sure that interrupt instructions are executed in succession.
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