Siemens SIMOTION D4 5-2 Series Commissioning And Hardware Installation Manual page 141

Bumpless media redundancy (MPRD), as of V4.3
MRRT is a procedure for bumpless media redundancy for PROFINET IO with IRT. MRRT
also requires MRP.
The combination of MRP with MRRT provides bumpless PROFINET operation for short
cycle times in the event of a fault in the ring. MRRT is based on IRT and ensures bumpless
operation by the provider sending the cyclic data in both directions which the consumers
then receive twice. If the ring is interrupted at one position (e.g. through the failure of a ring
node), receipt of the cyclic data via the problem-free side of the ring is still guaranteed.
Bumpless media redundancy MRRT always requires the activation of MRP in the individual
rings.
A maximum of two Ethernet nodes may be between the sync master and the redundant sync
master. If the redundant sync master is used together with MRRT, it is recommended that
the redundant sync master be connected directly to the sync master and the two nodes
located in a common control cabinet so that the cable connection between both nodes is
protected.
If there is an interruption in the link between the sync master and the redundant sync master,
the system continues to run without bumps, but after switching off and on again faults can
occur.
Too high a network load or too-rapid coming and going of faults can also result in
unfavorable cases in the failure of the PROFINET connection with activated MRRT because
of delayed or incomplete switchover actions of MRP/MRRT.
For example, with two consecutive faults at different points in the ring, bumpless operation is
only ensured when there is approx. three seconds between the two faults.
Additional information
You will find additional information about media redundancy in the
Communication
SIMOTION D4x5-2
Commissioning and Hardware Installation Manual, 02/2012
System Manual.
Parameter assignment / addressing
5.6 Configuring PROFINET IO
SIMOTION
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