Supplementary information 
  18.11 Communication via fault-tolerant S7 connections 
CPU 410 Process Automation/CPU 410 SMART 
System Manual, 05/2017, A5E31622160-AC 
335 
The number of connection resources required on the CPs depends on the network used.  
If you implement a duplex fiber-optic ring (see figure below), two connection resources are 
required per CP. In contrast, only one connection resource is required per CP if a double 
electrical network (see figure after next) is used. 
 
Figure 18-16  Example of redundancy with fault-tolerant system and redundant ring 
Configuration view ≠ Physical view 
 
 
Figure 18-17  Example of redundancy with fault-tolerant system and redundant bus system