Communication Between The Safety Program And The Standard User Program - Siemens SIMATIC S7 F Manual

Safety Mechanisms
3.9.1 Communication Between the Safety Program and the Standard
User Program
The standard and Safety Programs use different data formats. Special conversion
blocks must therefore be used for the data exchange.
F-CPU
From
Safety Program
Standard program
The following data types are supported: BOOL, REAL, INT and TIME.
Parameters are passed as safety-related F-data types in the Safety Program. If the
standard user program has to process data from the Safety Program, for
monitoring purposes, for example, then a block for the conversion of data (F_Fdata
type_data type) must be inserted in CFC to convert the F-data types to standard
data types.
These blocks can be found in the Failsafe Blocks, User Blocks library.
The F_Fdata type_data type blocks must be called in the standard user program
(CFC chart, standard run-time group).
If data from the standard user program has to be processed in the Safety Program,
safety-related F-data types must be created from the standard data types using
F_data type_Fdata type blocks for data conversion and, if necessary, then
subjected to a plausibility check programmed using fail-safe blocks. The F_data
type_Fdata type data conversion blocks must only be used in the Safety Program
(CFC chart, F-run-time group).
See Also
Programming Communication Between F User Programs and Standard User
Programs
3-10
Safety Program
Non-safety-related
Standard program
To
Standard program
Safety Program
Block
F_Fdata type_data type
F_data type_Fdata type
Safety-
Related
No
No
Fail-Safe Systems
A5E00085588-03