What is PROFINET MRP?

In ring topologies, a media redundancy can be established so if a wire breaks in any section of the ring, the secondary connection to the network can be used.

PROFINET networks offer management solutions for ring topologies with defined media redundancy classes - Media Redundancy Protocol (MRP) and Media Redundancy for Planned Duplication (MRPD).

The MRP set up in a ring topology required all nodes in it to support MRP, and at least one of the nodes to support MRP manager capabilities. So if for any reason the transmission is interrupted, the ring manager can immediately activate the alternative communication within the millisecond range.

In order to set up an MRPD ring, all nodes have to support the MRPD, and one of them to support MRDP manager capabilities, same as in the MRP case. Within this topology, all of the nodes support PROFINET IRT (CC-C devices) as well.

In an MRPD ring, each of the message senders transmits two equal frames to the receiver in opposite directions around the ring, so in case of a failure - the frame still arrives at the receiver destination.

So, MRDP ensures constant, non-stop connectivity with a zero-time recovery.