Siemens SIMATIC S7 System Manual page 34

Configurations and Help with Selection
2.2 Configuration of F-Systems
Example 2 for PROFIBUS DP:The S7-400 station with CPU 416F-2 is the DP master. The
F-CPU exchanges safety-related data with the IM 151-7 F-CPU in ET 200S.
The IM 151-7 F-CPU acts as an intelligent preprocessing device (I-slave).
The F-system can be expanded with additional fail-safe I/O, any number of "standard" DP
slaves and standard modules.
Figure 2-2
2-4
Example 2: F-System S7 Distributed Safety with PROFIBUS DP
Safety Engineering in SIMATIC S7
System Manual, 04/2006, A5E00109529-05