Operation Processing At Momentary Power Failure - Mitsubishi Electric MELSEC iQ-R Series User Manual

9.3

Operation Processing at Momentary Power Failure

When an input power supply voltage supplied to the power supply module falls below the specified range, a momentary power
failure is detected and the following operation processing is performed.
In a redundant system with redundant extension base unit, if a momentary power failure occurs in the power supply module
mounted on an extension base unit, operation processing in the CPU modules of both systems is interrupted.
However, when the power supply module is redundant, operation processing is not interrupted even if a momentary power
failure occurs in either of the power supply modules. But if a momentary power failure occurs when power is supplied to either
of the power modules, operation processing in the CPU modules of both systems is interrupted.
Momentary power failure not exceeding the allowable momentary power failure time
If a momentary power failure occurs, the event history is registered to suspend the operation processing. Note however that
measurement of the timer device continues. In addition, the output status is held.
■When the momentary power failure is cleared
Once the momentary power failure is cleared, the operation processing continues.
■Measurement of the watchdog timer (WDT) at a momentary power failure
Even if the operation is suspended due to a momentary power failure, measurement of the watchdog timer continues. For
example, assuming that the monitoring time of scan time is set to 200ms and the scan time is 190ms, a momentary power
failure of 15ms causes a WDT error. ( Page 200 Scan time monitoring time setting)
Momentary power failure exceeding the allowable momentary power failure time
This case results in initial start, the same operation processing as when the CPU module is powered on or is reset.
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9.3 Operation Processing at Momentary Power Failure