Basics of program execution
10.5 Asynchronous instructions
S7-1500R/H redundant system
334 System Manual, 01/2024, A5E41814787-AF
With a synchronous instruction, the instruction is fully executed in each call.
First call of the asynchronous instruction, start of execution
Intermediate call of the asynchronous instruction, execution continues.
Last call of the asynchronous instruction, completion of execution
A job is fully processed by a synchronous instruction with each call.
Duration of a fully executed job
Figure 10-5 Difference between asynchronous and synchronous instructions
Processing of an asynchronous instruction during the SYNCUP system state
-1500R/H redundant system executes SYNCUP, this extends the processing time for
an asynchronous instruction.
The dynamic behavior of the system
state SYNCUP requires that you call asynchronous
instructions cyclically (e.g. in OB 1).
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