Line Topology
In many installations, the use of line topology has several benefits, such as simpler cabling, use of smaller/fewer Ethernet
switches. The PROFINET interface supports line topology with its 2 ports and built-in Ethernet switch. If line topology is
used, precautions must be taken if more than 8 frequency converters in a line is installed. Each frequency converter in the
line will, due to the built-in Ethernet switch add a small delay the communication. This can lead to time out in the PLC, if
the the update time has been selected to a low value. If more than 8 frequency converters in line are installed, the update
time has to be set higher than 2 ms. Typically 4 ms does allow up to 16 frequency converters with a line. With 8 ms 32
frequency converters can be installed. The numbers given are typical values and may vary from installation to installation.
Illustration 3.7 Line Topology
NOTICE
In a line topology, all frequency converters must be powered either by mains, or by a 24 V DC option card, in order the
built-in switch to work.
Operate installing frequency converter of different power-sizes in a line topology may result in unwanted power-off
behavior, while using controlword timeout (parameter 8-02 Control Source to parameter 8-06 Reset Control Timeout. It is
recommended to mount the frequency converters with the longest discharge time first in the line topology. In normal
operation, frequency converters with bigger powersize has a longer discharge time.
How to Install Operating Instructions
12 Danfoss A/S © Rev. 2014-02-27 All rights reserved. MG90U302
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