Siemens SIMATIC CPU 410 System Manual page 330

Supplementary information
18.10 Communication via S7 connections
Configuring connections
Redundant connections between the point-to-point CP and the fault-tolerant system are not
necessary.
Figure 18-13 Example of connecting a fault-tolerant system to a single-channel third-party system via
Figure 18-14 Example of connecting a fault-tolerant system to a single-channel third-party system via
Response to failure
Double errors in the fault-tolerant system (i.e., CPUa1 and IM 153) and a single fault in the
third-party system lead to a total failure of communication between the systems involved.
This can be seen in the previous figure.
330
switched PROFIBUS DP
PROFINET IO with system redundancy
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC