Siemens SIMATIC PCS 7 - Figure 6-5 Example of Redundancy in a 1-Out-Of-2 System with Error

I/O configuration variants
6.3 Fault-tolerant automation systems (redundancy operation)
CPU 410 Process Automation/CPU 410 SMART
64 System Manual, 05/2017, A5E31622160-AC
With error/fault
The following figure shows how a component may fail without impairing the functionality of
the overall system.
Figure 6-5 Example of redundancy in a 1-out-of-2 system with error