Siemens SIMATIC S7-400 Configuration And Use Manual page 37

Hardware Components
An F-System consists of hardware components that fulfill certain safety
requirements, such as:
• A CPU, such as the CPU 417-4H, with an F-copy license
• F-I/Os
You can also expand the F--System with standard components.
Software Components
The software components of a S7 F-System include the following:
• S7 F Systems (Programming)
• S7 F Configuration Pack (Configuration of the F-I/Os)
• The fail-safe user program (F user program) on the CPU
Creating a Fail-safe User Program
You create the fail-safe user program in CFC using fail-safe blocks from the
"Fail-safe Blocks" library. For the connection to the F-I/Os, you use F channel and
module driver blocks, to which you have to assign parameters. Some of the
parameters are assigned automatically as a result of the hardware configuration of
the F-I/Os.
When the executable fail-safe user program is generated, safety tests are carried
out automatically and additional fault detection functions incorporated.
Automation System S7-400 Configuration and Use
A5E00442711-02
CPUs of the S7-400
2-21