Media Redundancy With Planned Duplication Of Frames (Mrpd) - Siemens SIMATIC ET 200AL System Manual

5.4.3

Media Redundancy with Planned Duplication of frames (MRPD)

MRP extension "Media Redundancy with Planned Duplication of frames" (MRPD)
The MRP extension "Media Redundancy with Planned Duplication of frames" (MRPD)
provides the advantage that, in the case of a failure of a device or a line in the ring, all other
devices continue to be supplied with IO data without interruption and with short update times.
MRPD is based on IRT and MRP. To realize media redundancy with short update times, the
PROFINET devices participating in the ring send their data in both directions. The devices
receive this data at both ring ports so that there is no reconfiguration time.
Requirements for media redundancy with MRPD
● All the devices of the ring must support MRPD, for example interface module IM
155-6 PN HS as of firmware version 4.0.
● You have configured MRP for all the devices of the ring. You have assigned the MRP role
"Not device in the ring" to devices that are not located in the ring.
● You have configured IRT for all the involved components.
Configuring MRPD
You do not have to explicitly activate MRPD in STEP 7. The function is available
automatically as soon as all the requirements for MRPD are fulfilled.
Redundancy levels of IO devices with MRPD
The redundancy level of an IO device specifies how strongly the real-time communication is
influenced in the case of a power interruption between an IO device and its IO controller.
● Full redundancy: No influence, because the IO controller and IO device are located in the
same ring.
● Partial redundancy:
– If the interruption takes place on a non-redundant part (line) between the IO device
– If the interruption takes place on a redundant part (ring), real-time communication is
● No redundancy: No redundant path between the IO device and its IO controller,
communication is always influenced.
The figure below shows the redundancy levels of the IO devices for an example
configuration with MRPD. The three devices in the ring and the switch have the redundancy
level "Full redundancy". Device 4 has the redundancy level "Partial redundancy", because
the connection between the switch and the device is not redundant.
PROFINET with STEP 7 V15
Function Manual, 12/2017, A5E03444486-AH
and IO controller, real-time communication is influenced.
not influenced.
5.4 Media redundancy (ring topologies)
Functions
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