Topology - Danfoss MCA 122 Modbus TCP Operating Instructions Manual

How to Install

2.1.3 Topology

The MCA 122 features a built-in Ethernet-switch, thus having two Ethernet RJ-45 connectors. This enables the possibility for
connecting several Modbus TCP options in a line topology as an alternative to the typical star-topology.
The two ports are equal, in the sense that they are transparent for the option. If only one connector is used, either port can
be used.
Illustration 2.4 Star Topology
Illustration 2.5 Line Topology
NOTICE
For line topology, refer to 2.1.5 Recommended Design Rules. In a line topology all frequency converters must be powered,
either by mains or by their 24 V DC option cards, for the built-in switch to work.
NOTICE
Observe that mounting frequency converters of different power-sizes in a line topology may result in unwanted power-off
behaviour.
Smaller frequency converters discharge faster than bigger frequency converters. This can result in loss of link in the line
topology, which may lead to control word timeout.
To avoid this, mount the frequency converters with the longest discharge time first in the line topology.
MCA 122 Modbus TCP
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