Safety Engineering in SIMATIC S7
System Manual, 04/2006, A5E00109529-05
5-1
Achievable Safety Classes with F-I/O
5
5.1
5.1
Introduction
Overview
This chapter presents the options available for achieving safety classes SIL2/Category 3 and
SIL3/Category 4 with fail-safe I/O in S7 Distributed Safety and S7 F/FH Systems. The
information relates to the F-I/O of the SIMATIC S7 product family, that is, S7-300 F-SMs,
F-modules ET 200S and ET 200pro, and the ET 200eco fail-safe I/O module.
Additional Information
The F-I/O used determines whether the options described can be implemented in your
application. For information on this, refer to the following manuals for the specific F-I/O:
•
For S7-300 F-SMs:
Automation System S7-300 Fail-safe Signal Modules manual
•
For ET 200S fail-safe modules:
ET 200S Distributed I/O System Fail-safe Modules
manual
•
For ET 200pro fail-safe modules:
ET 200pro Distributed I/O Device Fail-safe Modules
manual
•
For the ET 200eco fail-safe module:
ET 200eco Distributed I/O Station Fail-safe I/O
Module manual
Achieving the Safety Class for F-I/O with Inputs
The required safety class is achieved for F-I/O with inputs as follows:
•
Internally, using test circuits and automatic tests
•
Externally, by the type of sensor evaluation, that is, the wiring of the sensor determines
safety class SIL2/Category 3 or SIL3/Category 4
Achieving the Safety Class for F-I/O with Outputs
The required safety class is achieved for F-I/O with outputs as follows:
•
Internally, using test circuits and automatic tests
•
Externally, by the prescribed interconnection of the actuator
In addition, it may be necessary to have test signals from the process read by the F-I/O
and evaluated by the safety program.
