Omron CS Series Operator's Manual page 207

Cycle Time and Time
Minimum Cycle Time
Major Error Factors in the Virtual Cycle Time and Actual CS/CJ-series CPU Unit's Cycle Time
Computer Cycle Time
192
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The time elapse when Step Run will be as follows.
One step
execute
Virtual
Time
Enabling Minimum Cycle Time will set either the calculated value of the vir-
tual cycle time or the specified Minimum Cycle Time, whichever is greater, as
the virtual cycle time. The calculated value of the virtual cycle time can be
monitored in the detailed mode display of the [System Status].
The Minimum Cycle Time process in the virtual cycle time is not a process
Note
where the execution stands by till the cycle time reaches the specified value,
but where the Minimum Cycle Time is set.
Process Item
Computing Time
I/O Refresh Time
Peripheral Servicing time
The computer cycle time is the actual elapsed time of the Ladder Engine exe-
cuted on the computer, which is the execution time depending on the com-
puter's performance. It is different from the cycle time where an actual PLC
operates.
Wait One step Wait
execute
Instruction execution time
Error factor/Error range
Using such a lot of instructions that greatly varies in
instruction processing time depending on their pa-
rameters (e.g. Data Movement instructions) influences
the computing time. For example, a maximum of
322.35 ± 311.15 ms (1 word vs. 1000 words) error will
occur for one Block Transfer instruction execution.
For the Special I/O Unit, CPU Bus Unit, or Inner
Board, using such a Unit that varies in I/O refresh time
depending on the Unit's status or settings changes I/O
refresh time. For example, I/O refresh time will be
4.3 ms when the Position Control Unit (C200HW-
NC413) is mounted and 5.5 ms when reading/writing,
making an error of 1.2 ms.
When "Fixed Peripheral Servicing Time" is disabled,
4% of the immediately previous cycle time is serviced
for each event service. When the immediately previ-
ous cycle time is 10 ms, an error of 10 ms ´ 0.04 ´ 6
(event services) = 2.4 ms will occur if the longest time
is serviced for all of the event services.
Section 9-2
One step Wait One step
execute execute
Process