Siemens CPU 410-5H Process Automation System Manual page 76

I/O configuration variants
4.7 Connecting redundant I/O to the PROFIBUS DP interface
Using redundant digital input modules with redundant encoders
With redundant encoders you use digital input modules in a 1-out-of-2 configuration:
Figure 4-17
The use of redundant encoders also increases their availability. A discrepancy analysis
detects all errors, except for the failure of a non-redundant load voltage supply. You can
enhance availability by installing redundant load power supplies.
You will find interconnection examples in Appendix Connection examples for redundant I/Os
(Page 307).
Redundant digital output modules
Fault-tolerant control of a final controlling element can be achieved by connecting two
outputs of two digital output modules or fail-safe digital output modules in parallel (1-out-of-2
configuration).
Figure 4-18
The digital output modules must be connected to a common load voltage supply.
If you do not use terminal modules, see the interconnection examples in the Appendix
Connection examples for redundant I/Os (Page 307).
76
Fault-tolerant digital input modules in 1-out-of-2 configuration with two encoders
Fault-tolerant digital output modules in 1-out-of-2 configuration
CPU 410-5H Process Automation/CPU 410 SMART
System Manual, 10/2013, A5E32631667-AA