Media redundancy protocol, network
Support for improved stability and runtime loss prevention
Hillscher provides MRM and MRC functions for MRP


Hilscher announced on the 14th that its PROFINET IO device and equipment controller products now support the PROFINET Media Redundancy Protocol (MRP). MRP enables the use of a ring topology in PROFINET IO RT (Real-Time) networks and compensates for single errors.

The PROFINET protocol offers several technologies to enable system engineers to build deterministic industrial Ethernet networks with high availability and fail-safe capabilities. Among them, the ring topology is a technology that provides fast recovery times of less than 200 ms. MRP is required to use it in a PROFINET RT network.

Devices in a PROFINET RT network are typically configured in linear and star topologies to communicate status, control and diagnostic information between devices and equipment controllers. However, if the central device fails, this can have a serious impact on the entire network in the worst case. Therefore, to ensure network availability, a ring topology, which is not commonly used in Ethernet environments, is often applied as an alternative.

To ensure proper operation, MRP uses a Media Redundancy Manager (MRM) that constantly monitors the ring topology. If a network error is registered, it is designed to provide network redundancy information to the Media Redundancy Clients (MRC) in a linear topology. All PROFINET IO device controllers from Hilscher can act as MRMs in a PROFINET IO network. In addition, all PROFINET IO devices include MRC functionality.

When the MRM issues a test frame at regular intervals to evaluate the integrity of the ring network, the MRC forwards the test frame back to the MRM along the ring. If the MRM does not return the test frame, it interprets it as a network error, notifies all MRCs of the network error, and switches to a linear topology by transmitting control data. In addition, the MRC detects a link state change using one of its ports and forwards it to the MRM to reduce the time for the MRM to detect errors and repairs.