Connecting A Redundant I/O - Siemens SIMATIC S7-400H Manual

Using I/O on the S7-400H
6.4

Connecting a Redundant I/O

What is a redundant I/O?
A redundant I/O consists of input/output modules, of which several are present. If
you wish to use a redundant I/O, you can implement it at user level.
Configurations
The following configurations having a redundant I/O are possible (Figure 6-3):
1. Redundant system with one-way central and/or distributed I/O.
One I/O module is inserted for this purpose in the subsystems of CPU 0 and
one in the subsystem of CPU 1.
2. Redundant configuration with a switched I/O.
Two I/O modules are inserted into two ET 200M distributed I/O devices with
an active backplane bus.
Figure 6-3
Note
When using redundant I/O, a premium might have to be added to the calculated
monitoring times; refer to Section 5.3.2.
6-10
Redundant One-Sided and Switched I/Os
S7-400H Programmable Controller Fault-Tolerant Systems
Redundant one-sided I/O
Redundant switched I/O
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