Mitsubishi A2USCPU(S1), User Manual

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4. CPU MODULE
4.1.3 Operation processing upon instantaneous power failure
The PLC CPU detects a momentary power failure when input power voltage supplied to
the power supply module becomes lower than the specified range.
When the PLC CPU detects an instantaneous power failure, the following operation
processing is performed.
(1) When an instantaneous power failure shorter than allowable momentary power
failure period occurred:
(a) When an instantaneous power failure occurred, the operation processing is
interrupted while the output status is retained.
(b) When the instantaneous power failure is reset, the operation processing will be
continued.
(c) When an instantaneous power failure occurred and the operation was
interrupted, measurement of the watchdog timer (WDT) continues. For instance,
in the case that WDT is 200ms and the scan time is 190ms, if an instantaneous
power failure of 15ms occurs, it causes the watchdog timer error.
(2) When an instantaneous power failure longer than the allowable momentary power
failure period occurred:
The PLC CPU performs the initial start.
The operation processing is the same as power-on or reset operation with the reset
switch.
Operation processing upon instantaneous power failure
Instantaneous power failure occurred Power supply restoration
END 0
END
END
PLC CPU operation processing