Siemens SIMATIC PCS 7 Operating Manual page 87

Runtime groups of an F-program
The F-program is divided into several runtime groups, as shown in the table below.
Note
xx = Number of the cyclic interrupt OB
y = Consecutive numbering if several shutdown groups exist in a single cyclic interrupt OB
Chart
@F_ShutDn_xx
@F_ShutDn
@F_CycCo-OBxx
@F_TestMode
@F_IN_xx_y
@F_OUT_xx_y
@F_DbInitxx
All required error OBs are added to the block container in the SIMATIC Manager.
There should only be one @F_IN_xx_y runtime group before the first F-user runtime group
and one @F_OUT_xx_y runtime group after the last F-use runtime group. If the safety
program consist of several shutdown groups (see section 6.2.6 (Page 89)), there is the
@F_IN_xx_y and @F_OUT_xx_y runtime group both before and after the F-user runtime
group in the shutdown groups.
Compendium Part B - Process Safety (V8.2)
Operating Manual, 07/2016, A5E35031794-AB
F blocks
Shutdown logic of cyclic interrupt OB
The shutdown logic is created with RTGLOGIC and standard logic blocks.
Shutdown block
Where an F-program is present in several cyclic interrupt OBs, this runtime
group is integrated into the cyclic interrupt OB with the shortest call time.
The shutdown logic is created with F_SHUTDN, RTGLOGIC, and standard logic
blocks.
F_CYC_CO, F_TEST and F_TESTC (for tests)
F_TESTM for managing safety mode
F blocks which supply input values for the F-program
(F_QUITES, communication receive blocks, conversion blocks from standard to
F-data types, drivers for F-input modules)
Runtime groups with user logic, in the sequence in which they were created by
the user
Blocks which further process output values of F-blocks (communication send
blocks, conversion blocks from F-to standard data types, drivers for F-output
modules, F_PLK, F_PLK_O, and F_DIAG for program sequence control)
DB_INIT function block required for the cold restart of an F-runtime group
Configuring the safety program
7.2 Creating the safety program
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