Siemens SIMATIC S7 F Manual page 21

Product Overview
S7 FH System
The S7 FH System is a fail-safe, fault-tolerant automation system consisting of at
least the following components:
•
A fault-tolerant S7 400H system (master and standby) running a fail-safe (F)
user program
•
One or more fail-safe inputs/outputs (F-I/Os) in a distributed I/O device
(redundancy optional)
The following figure shows an example of an S7 FH configuration with a redundant
CPU, shared, switched distributed I/O modules connected via a redundant system
bus.
Fail-Safe Systems
A5E00085588-03
Redundant system bus (PROFIBUS or Ethernet)
Operator station
(System visualization)
Redundant
PROFIBUS - DP
Programmable controller
S7 FH System
ET 200M distributed I/O device
Fail - safe signal modules
(optionally redundant)
ET 200M distributed I/O device
Standard modules
(optionally redun dant)
1-5