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When connecting the RS485 bus, the A terminals,
the B terminals, the 24 V power supply and the
common terminals (ground) of the modules in a
device group, e.g. those on a particular floor (127
components maximum) must be connected to one
another. A connection diagram with bus system is
provided in the system manual. If the RS485 bus
is used, a bus terminator is required; you can find
information about the connection procedure in the
relevant operating manual.
5.2 Topology of the bus system
Power is supplied by the HMW-Sys-PS7-DR DIN
rail-mounted power supply unit or by another 24 V
power supply unit that is dimensioned in accor-
dance with the total number of modules available
on a particular floor, for example, and with the total
power consumed by those modules.
If programming and control is to be carried out
centrally via the HomeMatic central control unit, the
HMW bus cables from the individual modules, as
well as the cable originating from the control PC or
a CCU must converge at a suitable point deter-
mined by the building in question. This enables the
