Connecting Redundant I/Os - Siemens SIMATIC S7-400H System Manual

10.5

Connecting redundant I/Os

What is redundant I/O?
Input/Output modules are considered redundant when the system contains two sets of each
module, and these are configured and operated as redundant pairs. The use of redundant
I/O provides the highest degree of availability, because the system tolerates the failure of a
CPU or of a signal module.
Configurations
The following redundant I/O configurations are supported:
1. Redundant signal modules in the CPUs and expansion units
Figure 10-2
S7-400H
System Manual, 09/2007, A5E00267695-03
The signal modules are installed in pairs in the CPU 0 and CPU 1 subsystems.
Redundant I/O in central and expansion units
Using I/Os in S7-400H
10.5 Connecting redundant I/Os
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