Wiring
4.4 Requirements for Sensors and Actuators
ET 200pro Distributed I/O System - Fail-Safe Modules
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Operating Instructions, 05/2007, A5E00394073-02
Note
Note that replacing fail-safe modules in ET 200pro during operation will generate a
communication error in the F-CPU.
You must acknowledge the communication error in your safety program (for information
about F-system behavior after communication errors, fail-safe value output and user
acknowledgment, refer to the
S7 Distributed Safety, Configuring and Programming manual).
If the communication error is not acknowledged, the user data of the F-DO modules will
remain passivated (outputs at "0").
Remember to Set the PROFIsafe Address
When an F-module is replaced, make sure that the address switch (DIP switch) setting on
the electronic module is the same.
See also
Assignment of PROFIsafe Address (Page 24)
4.4
Requirements for Sensors and Actuators
General Requirements for Sensors and Actuators
Note the following important information for the safety-related use of sensors and actuators:
WARNING
Note that instrumentation with sensors and actuators bears a considerable safety
responsibility. Consider, too, that sensors and actuators do not generally withstand proof-
test intervals of 10 years as defined in IEC 61508 without considerable loss of safety.
The probability of dangerous faults and the rate of occurrence of dangerous faults of a
safety function must adhere to an SIL-based upper limit. You will find a list of values
achieved by F-modules under "Fail-Safe Performance Characteristics" in the technical
specifications for the F-modules.
To achieve SIL3 (Category 4), suitably qualified sensors and actuators are necessary.
