Basics of program execution
7.5 Asynchronous instructions
S7-1500R/H redundant system
162
System Manual, 10/2018, A5E41814787-AA
Difference between synchronous/asynchronous instructions
The figure below shows the difference between the processing of an asynchronous
instruction and a synchronous instruction. In the figure below, an asynchronous instruction is
called in five cycles before execution is completed, for example, a data record is transferred
in full.
①
First call of the asynchronous instruction, start of execution
②
Intermediate call of the asynchronous instruction, execution continues
③
Last call of the asynchronous instruction, completion of execution
④
A job is fully processed by a synchronous instruction with each call.
Duration of a fully executed job
Figure 7-5
Difference between asynchronous and synchronous instructions
Note
Processing of an asynchronous instruction during the SYNCUP system state
If the S7-1500R/H redundant system executes SYNCUP, this extends the processing time
for an asynchronous instruction.
Recommendation: Always access asynchronous instructions in the cyclic user program of
the S7-1500R/H redundant system, for example in OB 1.
Содержание Simatic S7-1500H
Страница 1: ......