Overview of Fail-safe Systems
1.4 Components of S7 Distributed Safety and S7 F/FH Systems
Safety Engineering in SIMATIC S7
1-10
System Manual, 04/2006, A5E00109529-05
1.4
1.4
Components of S7 Distributed Safety and S7 F/FH Systems
Hardware and Software Components of F-Systems
An overview of the hardware and software components required for configuring and
operating S7 Distributed Safety and S7 F/FH Systems F-systems is shown below.
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Figure 1-3
Overview of Hardware and Software Components of an F-System
Interaction of Components
To configure a fail-safe system, certain software and hardware components have to be
combined.
Wiring Fail-safe I/O
The user wires the F-I/O to the sensors and actuators so as to be able to achieve the
required safety class.
Configuring Hardware
The user configures the F-CPU and the F-I/O in
STEP 7
HW Config. This configuration must match the hardware configuration; that is, the circuit
diagram of the F-I/O must reflect the parameter settings.
Creating Safety Program
The user creates the safety program using a programming language in STEP 7.
For S7 Distributed Safety, the user creates fail-safe blocks in F-FBD or F-LAD. The
associated F-block library provides fail-safe blocks that the user can use in his safety
program. For the most part, the F-I/O is linked in the background without user involvement.
For S7 F/FH Systems, the user assigns parameters for the fail-safe blocks of the associated
F-block library and interconnects them in CFC. Special F-driver blocks
are available to link the F-I/O. These driver blocks must also be parameterized and
interconnected.
For both F-systems, safety checks are performed and additional F-blocks for fault detection
are incorporated automatically when the executable safety program is compiled.
