Communication Between Fault-Tolerant Systems And A Fault-Tolerant Cpu - Siemens SIMATIC PCS 7 CPU 410-5H System Manual

15.10.2

Communication between fault-tolerant systems and a fault-tolerant CPU

Availability
Availability can be enhanced by using a redundant plant bus and by using a fault-tolerant
CPU in a standard system.
If the communication peer is a fault-tolerant CPU, redundant connections can also be
configured, in contrast to systems with a standard CPU.
Note
Fault-tolerant connections use two connection resources on CP b1 for the redundant
connections. One connection resource each is occupied on CP a1 and CP a2 respectively.
In this case, the use of further CPs in the standard system only serves to increase the
resources.
Figure 15-19 Example of redundancy with fault-tolerant system and fault-tolerant CPU
Response to failure
Double errors in the fault-tolerant system, i.e., CPUa1 and CPa2, or single errors in the
standard system, i.e., CPUb1, lead to a total failure of communication between the systems
involved. This can be seen in the previous figure.
CPU 410-5H Process Automation
System Manual, 09/2014, A5E31622160-AB
15.10 Communication via fault-tolerant S7 connections
Supplementary information
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