Siemens SIMATIC ET 200AL, System Manual

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Functions
5.4 Media redundancy (ring topologies)
PROFINET with STEP 7
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Function Manual, 05/2021, A5E03444486-AL
Topology
The following schematic shows a possible topology for devices in a ring with MRP. The
devices inside the shaded oval are in the redundancy domain.
Example of a ring topology with the MRP media redundancy protocol:
Figure 5-37 Example of a ring topology with the MRP media redundancy protocol:
The following rules apply to a ring topology with media redundancy using MRP:
•
All devices must be connected to one other via their ring ports.
• All devices in the ring belong to the same redundancy domain.
• A device in the ring takes on the task of a redundancy manager.
– One device only has the role of "Manager". No other device may have the role of
"Manager". Or
– One device or multiple devices in the ring have the role of "Manager (auto)". The
devices with the role of "Manager (auto)" then negotiate between themselves which
device is to take on the role of redundancy manager. In this case, no device is
permitted to have the role of "Manager".
• All other devices in the ring are redundancy clients.
• You can connect up to 50 devices in a ring.
Non MRP-compliant devices can, for example, be connected to the ring via a SCALANCE X
switch or via a PC with a CP 1616.