Siemens SIMATIC PCS 7 - Introduction to the I;O Link to Fault-Tolerant System; Figure 6-6 Example of Redundancy in a 1-Out-Of-2 System with Total Failure

I/O configuration variants
6.4 Introduction to the I/O link to fault-tolerant system
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
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Failure of a redundant 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).
Figure 6-6 Example of redundancy in a 1-out-of-2 system with total failure
6.4
Introduction to the I/O link to fault-tolerant system
I/O installation types
In addition to the power supply module and CPUs, which are always redundant, the
operating system supports the following I/O installation types. You specify the I/O installation
types when configuring in HW Config.
Configuration
Availability
Fault-tolerant PROFINET IO (S2 with system redundancy)
or switched I/O
Enhanced
Redundant PROFINET IO (R1 with system redundancy) or
switched I/O
Enhanced
Redundant I/O
High