Supplementary information
15.15 Cycle and response times of the CPU 410-5H
CPU 410-5H Process Automation
300
System Manual, 09/2014, A5E31622160-AB
15.15.2
Calculating the cycle time
Extending the cycle time
The cycle time of a user program is extended by the factors outlined below:
●
Time-based interrupt processing
●
Hardware interrupt processing (see also Chapter Interrupt response time (Page 317))
●
Diagnostics and error processing (see also Chapter Example of calculation of the
interrupt response time (Page 319))
●
Communication via the integrated PROFINET IO interface and CPs connected by means
of the communication bus
(e.g.: Ethernet, Profibus, DP) as a factor in communication load
●
Special functions such as monitoring and modifying variables
or the block status
●
Transfer and deletion of blocks, compressing of the user program memory
●
Runtime of signals using the synchronization cable
Influencing factors
The table below shows the factors influencing the cycle time.
Table 15- 10 Factors influencing cycle time
Factors
Remark
Transfer time for the process
output image (POI) and process
input image (PII)
See tables from 19-3 onwards
User program execution time
This value is calculated based on the execution times of the vari-
ous statements (see the
S7-400 statement list
).
Operating system execution time
at the cycle control point
See Table 19-7
Extension of cycle time due to
communication load
You configure the maximum permitted communication load on
the cycle as a percentage in STEP 7 (Manual
Programming with
STEP 7
). See Chapter Cycle load due to communication
(Page 304).
Load on cycle times due to inter-
rupts
Interrupt requests can always stop user program execution. See
Table 19-8
