LSIS Master-K K1000S - The Operation During Momentary Power Failure

Chapter 4 CPU modules MASTER-K
4-3
2) Interrupt operation
When the CPU detects an interrupt signal, it stops the current operation and execute the
corresponding interrupt routine. After the interrupt routine is completed, the CPU resumes
to execute the previous operation from the stopped point.
The MASTER-K 200S/300S/1000S has two interrupt types that are time-driven interrupt
(TDI) and process-driven interrupt (PDI). Please refer the chapter 4.3.3 for details.
4.2.2 The operation during momentary power failure
The MASTER-K 200S/300S/1000S series can detect a momentary power failure, and the
CPU module decides to continue operation or not according to the period of momentary
power failure.
1) Less than 20msec
① The CPU stop to execute sequence program
retaining the state of output.
② The time measurement for internal timer and
time-driven interrupt keeps normal operation
status while the sequence program is
stopped.
③ When the AC power is recovered, the CPU
restarts to execute sequence program.
④ The external output of power supply module
is kept as the rated voltage and current.
2) Over 20msec
The CPU will initialized and restart operation
as the power re-applied.
Remark
Momentary power failure:
The power failure of PLC system means the state that AC input voltage is dropped below the
minimum value of rated input voltage range. When the period of power failure is short (usually,
the 1/2 cycle), it is called as momentary power failure.
Less than 20ms
Over 20ms