Download type A2USHCPU-S1 User's Manual

4. CPU MODULE
MELSEC-A
4.1.3 Operation processing upon momentary power failure
The PC CPU detects a momentary power failure when input power voltage supplied to the power
supply module becomes lower than the specified range.
When the PC CPU detects a momentary power failure, following operation processing is performed.
(1) When a momentary power failure shorter than allowable period of momentary power failure
occurred:
(a) When a momentary power failure occurred, operation processing is interrupted while the
output state is retained.
(b) When the momentary power failure is reset, operation processing will be continued.
(c) When a momentary power failure occurred and the operation was interrupted, measurement
of the watchdog timer (WDT) continues. For instance, when the scan time is 190ms and a
momentary power failure of 15ms occurs, it causes the watchdog timer error (200ms).
Momentary power failure occurred
END 0
Power supply restoration
END
END
A2USHCPU-S1 interrupts the operation.
Operation processing upon momentary power failure
(2) When a momentary power failure longer than the allowable period of momentary power
failure occurred:
The PC CPU performs the initial start. The operation processing is the same as power-on or reset
operation with the reset switch.
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