Installing and connecting
9
DL bus and M-Bus connections
The polarity of the
M-Bus
connection is reversible.
Data link for DL bus
The DL bus has 2 wires:
DL
and
GND
(sensor earth). The DL bus itself supplies the power supply for
the DL bus sensors.
Cables can be routed with a star topology or in series (from one device to the next).
Any cable with a cross-section of 0.75 mm² up to 30 m in length can be used as a
data link
. For longer
cables, we recommend the use of a screened cable.
Long cable conduits routed closely next to each other for mains and data links result in faults being
induced into the data link from the mains. We therefore recommend a minimum clearance of 20 cm
between two cable conduits or the use of screened cables.
Never run the data link together with a CAN bus cable or M-Bus cable in the same conduit.
Bus load from DL sensors
A 2-pole cable provides
both
the power supply and the signal transfer from DL bus sensors. An
additional power supply by means of an external power supply unit (such as with the CAN bus) is not
possible.
Take the "
bus load
" into consideration as sensors have a relatively high current demand:
The bus converter supplies the maximum bus load of
100 %.
The bus loads of the electronic sensors
are listed in the technical data of the relevant sensors.
Example
: The electronic sensor FTS4-50DL has a bus load of
25 %
. Consequently up to four
FTS4-50DL sensors can be connected to the DL bus.
M-Bus cable
The M-Bus has 2 wires:
M-Bus
and
GND
(sensor earth). The power supply for reading data from M-
Bus devices is provided by the bus converter.
Cables can be routed with a star topology or in series (from one device to the next). Ring topology is
not permitted.
A two-wire screened cable is used as the
M-Bus cable
(e.g. telephone cable J-Y(ST)Y 2 x 2 x 0.8 mm).
The maximum total cable length depends on the number of M-Bus devices connected and the cable
cross-section.
Never run the M-Bus cable together with a CAN bus cable or DL bus cable in the same conduit.
