Component Parts Of The Cycle Time - Siemens SIMATIC S7-300 Series Reference Manual

Cycle and Reaction times
3.1 Cycle time
Cycle Time – A Definition
The cycle time is the time that elapses during one program cycle.

Component Parts of the Cycle Time

The cycle time comprises:
Factors
Operating system execution time
Process image transfer time
(PII and PIO)
User program execution time
S7 timer (not in the case of the
CPU318-2)
PROFIBUS DP
Integrated functions
Communication via the MPI
Loading through interrupts
Figure 3-1 shows the component parts of the cycle time
Operating
system
User
program
Figure 3-1 Component Parts of the Cycle Time
3-2
See Section 3.2
Can be calculated on the basis of the execution times of the
individual instructions (see the S7-300 Instruction List ) and a
CPU-specific factor (see Table 3-3)
See Section 3.2
You configure the maximum permissible cycle load produced by
communication in percent in STEP 7
See Sections 3.4 and 3.5
PII
Operating
system
Interrupts
User
program
PIO
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
Remarks
A5E00111190-01