Siemens SIMATIC S7 System Manual page 143

F-Application Blocks
S7 Distributed Safety: Block container in the
application blocks.
F-blocks (F-FBs, F-FCs) with ready made functions in the Distributed Safety F-library. The F-
application blocks can be called by the user in the -> F-PB and in additional -> F-FBs and ->
F-FCs.
F-Attribute
S7 Distributed Safety: All -> F-blocks associated with the -> safety program have an F-
attribute (identified in the "Safety Program" dialog by an "F" in the F-block symbol). Once the
-> safety program has been compiled successfully, only the blocks of the -> safety program
have an F-attribute.
Fault Reaction Function
-> User safety function
Fault Reaction Time
The maximum fault reaction time for an F-system is the time between the occurrence of any
fault and a safe reaction at all affected fail-safe outputs. For the overall F-System: The
maximum fault reaction time is the time between the occurrence of any fault in any F-I/O and
a safe reaction at the associated fail-safe output.
For inputs: The maximum fault reaction time is the time between the occurrence of the fault
and the safe response on the backplane bus.
For digital outputs: The maximum fault reaction time is the time between the occurrence of
the fault and the safe response at the digital output.
F-Blocks
Fail-safe blocks of the -> safety program
F-CALL
S7 Distributed Safety: "F-call block" for the -> safety program. The F-CALL is created by the
user as an FC in the "F-CALL" programming language; "F-CALL" cannot be edited. The F-
CALL calls the -> F-runtime group from the -> standard user program. It contains the call for
the -> F-PB and the calls for the automatically added F-blocks (-> F-SBs, -> automatically
generated F-blocks, -> F-shared DB) of the F-runtime group.
F-Channel Drivers
S7 F/FH Systems: F-channel drivers provide process data in a safe format. The user must
position and interconnect the F-channel drivers in the -> safety program.
F-Communication DBs
S7 Distributed Safety: Fail-safe data blocks used for safety-related CPU-CPU
communication via S7 connections.
Safety Engineering in SIMATIC S7
System Manual, 04/2006, A5E00109529-05
Distributed Safety
F-library containing F-
Glossary
Glossary-5