Siemens SIMATIC PROFINET Function Manual page 151

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.
①
②
③
④
Figure 5-37
PROFINET with STEP 7 V14
Function Manual, 09/2016, A5E03444486-AG
and IO controller, real-time communication is influenced.
not influenced.
IO controller in the ring
IO device in the ring with redundancy level "Full redundancy"
Switch in the ring with redundancy level "Full redundancy"
IO device in the spur with the redundancy level "Partial redundancy"
Example configuration with MRPD
5.4 Media redundancy (ring topologies)
Functions
151