Siemens Simatic S7-1500 Function Manual page 38

Dependency of maximum cycle time on the configured communication load
The diagram shows the nonlinear relationship between maximum cycle time and configured
communication load with a pure cycle time of 10 ms. No interruptions occur in the example.
①
Figure 3-7
The described influence of the communication load on the execution time applies to all OBs
with a priority < 15.
Reducing the cycle time with a lower communication load
You can reduce the setting for the communication load in the hardware configuration. If you
set a communication load of 20% instead of 50%, for example, the cycle time extension due
to the communication is reduced from a factor of 2 to 1.25.
Cycle and response times
Function Manual, 10/2018, A5E03461504-AD
CPUs 1516T(F)-3 PN/DP, 1517(F)-3 PN/DP, CPU 1517T(F)-3 PN/DP, CPU 1518(F)-4 PN/DP,
1518(F)-4 PN/DP MFP: The (minimum) communication load that can be set is 5%.
Maximum cycle time depending on the configured communication load
Cyclic program execution
3.2 Cycle time
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