Siemens SIMATIC S7-1500 System Manual page 26

System overview
4.1 What is the S7-1500R/H redundant system?
The following picture shows a configuration of the S7-1500R in the PROFINET ring.
①
②
③
④
Figure 4-4 S7-1500R configuration in PROFINET ring
Principle of operation
One of the two CPUs in the redundant system takes on the role of primary CPU. The other
CPU takes on the role of the following CPU (backup CPU). The role of the CPUs can change
during operation. Synchronization of primary and backup CPU ensures rapid switchover
between CPUs in the event of a failure of the primary CPU. If the primary CPU fails, the
backup CPU takes over control of the process as the new primary CPU.
The redundancy connections use part of the bandwidth on the PROFINET cable for the
synchronization of the R-CPUs. This bandwidth is therefore not available for PROFINET IO
communication.
26
R-CPU (CPU 1515R-2 PN)
PROFINET cable (redundancy connections, PROFINET ring)
IO device
Switch
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD