Fault-tolerant automation systems
2.2 Increasing the availability of plants
S7-400H
System Manual, 03/2012, A5E00267695-11
29
With error/fault
The following figure shows how a component may fail without impairing the functionality of
the overall system.
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Figure 2-4 Example of redundancy in a 1-out-of-2 system with error
Failure of a redundancy node (total failure)
The following figure shows that the overall system is no longer operable, because both
subunits have failed in a 1-out-of-2 redundancy node (total failure).
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5HGXQGDQWQRGHVZLWKRIUHGXQGDQF\
Figure 2-5 Example of redundancy in a 1-out-of-2 system with total failure
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