General Information About The Bus System; General Information On The Installation; Topology Of The Bus System - HomeMatic HMW-LGW-O-DR-GS-EU Installation And Operating Manual

5 General information about the
bus system

5.1 General information on the installation

When connecting the RS485 bus, the A terminals
(1.3), the B terminals (1.7), the 24 V power supply and
the ground terminal (1.8) of the modules of a sub-
distribution (max. 127 segments) are to be connected
with one another. A bus terminator is always required
for this installation.

5.2 Topology of the bus system

The HomeMatic Wired components should always be
mounted in groups of sub-divisions to provide a better
overview. The number of sub-divisions that is appropri-
ate depends on the type and size of the project and is
to be defined accordingly. Installing at least one sub-
division on each level is recommended. Larger buil-
dings may require planning several sub-divisions per
level (e.g. separate for every floor). Bus cabling and a
ground cable have to be installed between the distribu-
tors. All load and control wiring should also be run in a
star format to the respective sub-divisions.
The power is supplied via a 24V DIN rail power supply
unit (24V VDC power supply with stabilized output vol-
tage) according to the number and total current con-
34