Siemens SIMATIC S7-1500 System Manual page 50

System overview
4.3 S7-1500 R/H-CPUs
In a redundant system, an IO device with system redundancy S2 has a system redundancy AR
with each of the two CPUs (IO controllers). An IO device thus supports ARs of two IO
controllers simultaneously (for the same modules).
A system redundancy AR can be either a primary AR or a backup AR. An IO device activates
the data of the primary AR at the outputs. The data of the backup AR are not initially
evaluated.
• Behavior in system state RUN-Redundant:
Both CPUs are IO controllers. The PROFINET communication runs simultaneously on both
system redundancy ARs, in each case between one of the CPUs (IO controllers) and the IO
device. If the primary CPU fails or is switched to STOP, then the backup CPU becomes the
primary CPU and also switches the backup AR to primary AR. The data of this AR becomes
active at the outputs.
With line topology, only the primary AR can fail. In this case the previous backup AR is
switched over to the primary AR, but the roles of the CPUs remain unchanged.
• Behavior in system state RUN-Solo:
Only the primary CPU is an IO controller. PROFINET communication runs on the primary AR
between the primary CPU and the IO device. There is no AR between the backup CPU and
the IO device.
In STEP 7, assign an IO device with system redundancy S2 to both CPUs of the redundant
S7-1500R/H system.
System redundancy R1
As of FW version V3.0, the S7-1500H redundant system supports IO devices with system
redundancy R1.
System redundancy R1 is the connection of an IO device via two interface modules, each of
which supports an AR to an IO controller in the redundant system. An IO device can
communicate via two separate PROFINET networks (subnets) through the two interface
modules.
IO devices with system redundancy R1 enable uninterrupted process data exchange with the
S7-1500H redundant system when:
• a CPU fails
• Interruption of the PROFINET ring or of the line topology
• an interface module fails
• a subnet fails.
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S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD