Siemens SIMATIC PCS 7 Operating Manual page 88

Configuring the safety program
7.2 Creating the safety program
Rules for F-runtime groups in the safety program
● We recommend that you proceed as follows in order to make the lengths of the F-cycles
as uniform as possible:
If you mix F-and standard runtime groups in a cyclic interrupt OB, you must execute the
F-runtime groups before the standard runtime groups.
● The following defaults are set for properties of an F-runtime group:
– Reduction ratio = 1
– Phase offset = 0
● You are not permitted to move automatically generated F-runtime groups
(identified by @).
Note
The feature: Optimize Run Sequence in CFC can lead to a change in the collective signature
and impair the response times of the safety program, and therefore should not be used in F-
runtime groups.
With PCS 7 V7.0 SP1 and higher, it is no longer possible to optimize the run sequence for
cyclic interrupt OBs with F-runtime groups.
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Compendium Part B - Process Safety (V8.2)
Operating Manual, 07/2016, A5E35031794-AB