LG Electronics 120S user manual Operation Processing at Momentary Power Failure Occurrence

Chapter 5 Power Supply / CPU

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

→ The operation processing is maintained

Input power

Momentary power failure within 1Oms

2) Momentary power failure exceeding 10 ms

Input power

→ The re-start process is executed as the power is re-applied.

Power failure exceeding 1Oms

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).

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