Redundancy - Siemens SIMATIC S7-1500 System Manual

System overview
4.3 S7-1500 R/H-CPUs
Redundancy connections (syn­
chronization link)
System redundancy
Hot standby
1)
Switchover time
1) The switchover time is the time starting with the failure or stop of the primary CPU until the backup CPU becomes the
primary CPU and assumes control of the process as the primary CPU at the point of interruption. The switchover time can
lengthen the cycle time.
Reference
The full technical specifications can be found in the manuals for the CPUs and on the Internet
(https://mall.industry.siemens.com).
4.3.2

Redundancy

Introduction
In the following section you will get an overview how to achieve a higher network and plant
availability in S7-1500R/H redundant systems.
The Media Redundancy Protocol (MRP) enables the connection of IO devices based on ring
topologies.
Despite a network failure (switch failure, line interruption), MRP can ensure communication
via alternative paths throughout the network.
MRP interconnection enables larger quantity structures by redundantly coupling two or
more rings with MRP in PROFINET networks.
The S7-1500R/H redundant system requires media redundancy (MRP) in the PROFINET ring.
As of firmware version V3.0, the H-CPUs no longer have to be part of a PROFINET ring. This
also allows other topologies, such as line topology.
MRP and MRP interconnection can be used independently of the system redundancy of the IO
devices.
You can use the following IO devices on the redundant S7‑1500R/H system:
• IO devices with system redundancy S2
• IO devices with system redundancy R1 (only S7-1500H as of FW version V3.0)
• Standard IO devices over the "Switched S1 device" function of the CPU
The System redundancy S2, R1 tolerates errors in the direct IO controller and IO device
communication.
With a switched S1 device, an interruption of the IO controller and IO device communication
is not tolerated. The S1 device fails temporarily and is then resumed if necessary.
46
CPU 1513R-1 PN CPU 1515R-2 PN
PROFINET ring PROFINET ring
Yes Yes
Yes Yes
300 ms 300 ms
CPU 1517H-3 PN CPU 1518HF-4 PN
Fiber-optic cable Fiber-optic cable
Yes Yes
Yes Yes
50 ms 50 ms
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD