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Chapter 5 Power Supply / CPU
5-7
2) Interrupt operation method
If a situation occurs which is requested to be urgently processed during execution of a PLC program, this opera
tion method processes immediately the operation, which corresponds to interrupt program. The signal, which infor
ms the CPU of those urgent conditions is called interrupt signal. The MASTER-K120S CPU has three kind of int
errupt operation methods, which are internal, external and high speed counter interrupt signal methods.
5.3.2 Operation Processing at Momentary Power Failure Occurrence
The momentary power failure occurs when the input line voltage to the power supply falls down below the rated
voltage. When momentary power failure within 10ms occurs, the CPU maintain operation processing. But If is exceeds
10ms, CPU stop processing and all output turns off. And The re-start process is executed as the power is re-applied.
1) Momentary power failure within 10 ms
2) Momentary power failure exceeding 10 ms
REMARK
1) Momentary power failure
The PLC defining power failure is a state that the voltage of power has been lowered outside the allowable
variation range of it. The momentary power failure is a power failure of short interval (several to tens ms).
Input powe
r
Momentary power failure
within 1Oms
→ The operation processing is maintained
Input powe
r
Power failure exceeding 1Oms
→ The re-start process is executed as the power is re-applied.