S7-400 Cycle And Reaction Times; Cycle Time - Siemens SIMATIC S7-400H System Manual

S7-400 cycle and reaction times

This section describes the decisive factors in the cycle and reaction times of your of S7-400
station.
You can read out the cycle time of the user program from the relevant CPU using the
programming device (refer to the manual
STEP 7
The examples included show you how to calculate the cycle time.
An important aspect of a process is its reaction time. How to calculate this factor is described
in detail in this section. When operating a CPU 41x-H as master on the PROFIBUS-DP
network, you also need to include the additional DP cycle times in your calculation (see
section Reaction time (Page 271)).
Further information
For more detailed information on the following execution times, refer to the Instruction list
S7-400H. This lists all the
along with their execution times and all the SFCs/SFBs integrated in the CPUs and the IEC
functions that can be called in
16.1

Cycle time

This section describes the decisive factors in the cycle time, and how to calculate it.
Definition of cycle time
The cycle time is the time the operating system requires to execute a program, i.e. to
execute OB 1, including all interrupt times required by program elements and for system
activities.
This time is monitored.
Time slice model
The program, and so also the user program, is executed cyclically in time slices. To
demonstrate the processes, let us presume a global time slice length of exactly 1 ms.
S7-400H
System Manual, 09/2007, A5E00267695-03
).
STEP 7
Configuring Hardware and Connections with
instructions that can be executed by the particular CPUs
STEP 7
with their execution times.
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