Safety Program Creation - Configuration Example
4.4 Creating the missing (F-)blocks
The blocks that have already been automatically created can be viewed in the project
folder of the SIMATIC Manager under:
CDx-75
S7 Program(1) --> Blocks.
All fail-safe blocks are shown with a yellow background to distinguish them from
blocks of the standard user program.
4.4.1 Program structure
The safety program is accessed by calling up the F-CALL from the standard user
program. The F-CALL is called up directly e.g. in the cyclic interrupt OB OB 35.
Cyclic interrupt OBs have the advantage that they interrupt the cyclic program
processing in OB 1 of the standard user program at fixed time intervals, i.e. in a cyclic
interrupt OB the safety program is called up and processed at fixed time intervals.
After the safety program has been processed, the standard user program is further
processed.
4.4.2 F-Runtime Group
To facilitate handling, the safety program consists of an "F-Runtime Group". The F-
Runtime Group is a logic construct consisting of a number of related F-Blocks, which
is formed internally by the F-System.
The F-Runtime Group comprises:
● one F-Call block F-CALL, "FC1"
● one F-Program block, to which the F-CALL is assigned, "FC2"
● further F-FBs
● several F-DBs
● F-Periphery-DBs
● F-System blocks F-SBs
● automatically generated F-Blocks
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