Response Time - Siemens SIMATIC CPU 410 System Manual

Supplementary information
18.16 CPU 410 cycle and reaction times
Further effects on the actual cycle time
Seen statistically, the extension of cycle times due to communication load leads to more
asynchronous events occurring within an OB 1 cycle, for example interrupts. This further
extends the OB 1 cycle. How much it is extended depends on the number of events per OB
1 cycle and the time required for processing these events.
Remarks
● Change the value of the "communication load" parameter to check the effects on the
cycle time during system runtime.
● Always take the communication load into account when you set the maximum cycle time,
otherwise you risk timeouts.
18.16.4

Response time

Definition of response time
The response time is the time from detecting an input signal to changing the output signal
associated with it.
Fluctuation range
The actual response time lies between the shortest and the longest response time. You must
always assume the longest response time when configuring your system.
The shortest and longest response times are analyzed below so that you can gain an
impression of the variation of the response time.
Factors
The response time depends on the cycle time and the following factors:
● Delay of the inputs and outputs
● Additional DP cycle times on the PROFIBUS DP network
● Execution in the user program
Delay of inputs/outputs
Make allowances for the following module-specific delay times:
● For digital inputs: the input delay time
● For interrupt-capable digital inputs: the input delay time + internal preparation time
● For digital outputs: negligible delay times
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CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC