10
CAN Bus network
Terminal diagram, CAN bus cable
Guidelines for the topology of a CAN network
Technical principles
The CAN BUS comprises the cables CAN-High,
CAN-Low, GND and one +12 V supply cable for
BUS components without their own power supply.
The combined total load of all devices with 12 V
and 24 V supply must not exceed 6 W.
Design CAN networks in a linear fashion and set a
terminator at each network termination. This is
ensured by the termination of the end devices. In
the case of larger networks (covering several
buildings), problems can occur through electro
-
magnetic interference and potential differences.
To avoid or to the greatest extent manage such
problems, take the following measures:
• Cable screening
The BUS cable screen must be connected well at every node to provide continuity. For larger net
-
works we recommend including the screen in the equipotential bonding, in line with the exam
-
ples shown.
• Equipotential bonding
As low an ohm connection as possible to the earth potential is particularly important. Where
cables enter buildings, ensure that the cable entries are in the same location where possible and
that all are connected to the same equipotential bonding system (S
ingle
E
entry
P
oint
principle). The
purpose is to create potentials that are as similar as possible, in order to achieve the smallest
possible potential difference to adjacent lines in case one line suffers a voltage surge (lightning
strike). Also ensure a corresponding clearance between the cable and lightning protection sys
-
tems.
The equipotential bonding also has positive properties to counteract interferences emitted from
linked cables.
