Danfoss VLT Profinet MCA 120 Operating Instructions Manual page 15

How to Install Operating Instructions
Ring/Redundant Line Topology
3 3
Illustration 3.8 Ring/Redundant Line Topology
For higher availability of a Ethernet network the usage of ring topology can increase the availability. For ring topology, a
special switch (redundancy manager) has to be installed between the PLC and the frequency converters. The redundancy
manager switch has to be configured so that the ports that connects to the ring are clearly defined. The main redundancy
manager hereafter sends test frames into the ring to detect if the ring is still up and working. If the switch does detect a
fault in the ring, it reconfigures the ring into 2 lines instead. The transition from one ring into 2 lines can take up to 500 ms
depending on the connected components that are installed in the ring. If the PLC has to run through this time without
fault, the PLC's timing has to be set, so that this time does not lead to time out fault.
NOTICE
For this type of topology it is crucial that the network switch supports detection of loss of line topology. The switch
inside the PROFINET option does not support this, but it must be supported in the redundancy manager that connects
the ring to the controller/network. Consult the manual of the switch for more information.
MG90U302 Danfoss A/S © Rev. 2014-02-27 All rights reserved. 13