Cycle and Response Times
7-2
ET 200S Interface Module IM 151/CPU
A5E00058783-01
7.1 Cycle time
Cycle Time – A Definition
The cycle time is the time that the operating system requires to process a program
cycle – i.e. an OB 1 cycle – as well as all the program sections and system
activities interrupting this cycle.
This time is monitored.
Components of the Cycle Time
Factors Remarks
Operating system execution time See Table 7-1
Process image transfer time (PII and
PIQ)
See Table 7-2
User program execution time Is calculated from the execution times of the
individual instructions and a CPU-specific factor
(see Table 7-3).
S7 timers See Table 7-4
Loading through interrupts See Table 7-5
The following figure shows the components that make up the cycle time:
PII
Operating
system
Cyclic user
program (OB 1)
PIQ
Interrupts
Operating
system
Acyclic user
program (e.g.
OB 40/82)
Figure 7-1 Component Parts of the Cycle Time
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