System And Media Redundancy At The Profinet Io Interface; System Redundancy; Figure 4-11 S7-400H System With Io Devices Connected In System Redundancy - Siemens SIMATIC PCS 7 CPU 410-5H System Manual

I/O configuration variants

4.6 System and media redundancy at the PROFINET IO interface

4.6 System and media redundancy at the PROFINET IO interface
4.6.1

System redundancy

System redundancy is a connection of IO devices via PROFINET IO in which a
communication connection exists between each IO device and each of the two fault-tolerant
CPUs. This communication connection can be set up using any topological interconnection.
The topology of a system alone does not indicate if an IO device is integrated in system
redundancy.
Contrary to a one-sided connection of IO devices, the failure of a CPU does not result in the
failure of the IO devices connected with this CPU.
Configuration
The figure below shows a configuration with two IO devices connected in system
redundancy.
Figure 4-11
This topology has the following advantage: The entire system can continue to operate in
case of an interrupted connection, no matter where it occurs. One of the two communication
connections of the IO devices will always remain intact. The IO devices that were redundant
until now will continue operating as one-sided IO devices.
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S7-400H system with IO devices connected in system redundancy
CPU 410-5H Process Automation
System Manual, 09/2014, A5E31622160-AB