Cycle Time and Time Section 9-2
193
Calculating Computer Cycle
Time
In calculating the computer cycle time, the followings are different from that
of the CS/CJ-series CPU Unit.
Process name Process Contents Processing time and Fluctuation
factors
(1) Overseeing Proc-
essing
Back up the I/O memory areas Time for I/O memory areas back-
up
(2) Computing Process Process instructions of the user program
in UM1 and UM2. Sum of the execution
time of instructions.
Sum of the instruction execution
time for UM1 and UM2
(3) Minimum Cycle
Time Calculation
Calculate the cycle time.
Enabling "Minimum Cycle Time" in PLC
Setup will wait for the cycle time to com-
plete with WDT resetting.
Approximate to 0 for the time when
Minimum Cycle Time is not set.
The additional time for Minimum
Cycle Time = The cycle time
specified as Minimum Cycle Time -
The computer cycle
time((1)+(2)+(4)+(5))
(4) I/O Refresh Not processed in the computer cycle time. 0 ms
(5) Peripheral Servicing An event service with the CS/CJ-series
Special I/O Unit, targeting the Network
Communications Unit and the Serial
Communications Unit.
Note: I/O refresh is not included.
All of the services that occurred in
the cycle are executed regardless
of the setting of Fixed Peripheral
Servicing Time" of PLC Setup.
Computer cycle time = (1) + (2) + (3) + (5)
Note The computer cycle time may greatly fluctuate depending on the execution
environment such as file access and memory swapping.
Time Elapse in Computer
Cycle Time
The time elapse when Continuous Run in the computer cycle time is the
same as that on the computer.
Time
One step
execute
One step
execute
One step
execute
One step
execute
Process
Note: The dashed
line shows
the time
elapse in
the virtual
cycle time.
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