Topology Of The Bus System - HomeMatic HMW-IO-12-Sw7-DR Installation And Operating Manual

Control side
On the control side however, only non-hazardous
safety extra-low voltages are used. Since there is
electrical isolation between the load and control sides
in the module, no mains power capable wires have to
be used. Using interior telecommunications wiring or
comparable control wiring is recommended. Make sure
however, that the wires of the load and the control side
are separated conforming with VDE regulations within
the sub-distribution. Keep a minimum spacing of 8 mm
between the two types of wiring.
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 con-
nected with one another. A connection diagram with
bus system is provided in the system manual. When
using several modules, a bus termination is required.
Information on the connections is provided in the
respective operating instructions.
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5.2 Topology of the bus system

The HMW components should always be mounted in
groups of sub-divisions to provide a better overview.
The number of sub-divisions that is appropriate de-
pends 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 buildings may require planning
several sub-divisions per level (e.g. separate for every
floor). All load and control wiring should also be run
in a star format to the respective sub-divisions. The
power supply is done through a DIN rail power supply
HMW-Sys-PS7-DR or another 24 V power supply
dimensioned according to the number and total current
consumption of all existing modules in the respective
sub-division. If central programming and control is to
be done through the HomeMatic Centre, the HMW
bus lines for the individual sub-divisions and the lines
coming from the control PC or a Centre should be
run together in a room according to available space
in order to achieve a separation of the individual bus
segments and to simplify troubleshooting if necessary.
Normally, this is the room in which the HomeMatic
system Centre is installed.
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