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Chapter 4 CPU Function
4 - 3
4.2.2 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 occurs within 10ms, the PLC option card
maintain operation processing. But if it exceeds 10ms, PLC option card stops 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 option card 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).
4.2.3 Scan Time
The processing time from a 0 step to the 0 step of next scan is called scan time.
1) Expression for scan time
Scan time is the sum of the processing time of scan program that the user has written, of the
task program processing time and the PLC option card internal processing time.
(1) Scan time = Scan program processing time + Interrupt program processing time +
PLC option card internal processing time
• Scan program processing time = The processing time used to process a user program
that is not specified to a task program.
• Interrupt program processing time = Total of the processing time of interrupt programs
executed during one scan.
• PLC option card
internal processing time = Self-diagnosis time + I/O refresh time + Inte
rnal data processing time + Communications service proce
ssing time
Input
Power
Momentary power failure
within 1Oms
→
The operation processing is maintained.
Input
Power
Power failure exceeding
→
The re-start process is executed as the power is
re-applied.
Содержание SV-iS7 PLC
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