Siemens CPU 410-5H Process Automation System Manual page 241

Figure 16-9
If the plant bus is configured as a duplex fiber-optic ring, the communication of the systems
involved is maintained if a break of the two-fiber fiber-optic cable occurs. The systems then
communicate as if they were connected to a bus system (linear structure); see following
figure.
Figure 16-10 Example of linking of standard and fault-tolerant systems in a redundant ring
CPU 410-5H Process Automation/CPU 410 SMART
System Manual, 10/2013, A5E32631667-AA
Example of linking standard and fault-tolerant systems in a redundant bus system
Supplementary information
16.9 Communication via S7 connections
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