DeviceNet • 109
Network Architecture
WAGO-I/O-SYSTEM 750
DeviceNet
Note
WAGO offers the screen connection system (series 790) for an optimum con-
nection between fieldbus cable screening and functional earth.
Each DeviceNet node forms the differential voltage U
Diff
with: U
Diff
=
U
CAN_High
- U
CAN_Low
. using the bus levels CAN_High and CAN_Low.
Differential signal transmission offers the advantage of an insensitivity com-
pared to common mode malfunctions and ground offset between the nodes.
Note
At its conductor ends, the bus cable must always be connected with a match-
ing resistor of 120 Ohm to avoid reflections and, as a result, transmission
problems.
This is also required for very short conductor lengths.
The CAN bus is a 2-wire bus and bus error management can detect a cable
break or a short-circuit by the asymmetric operation.
Further information
The CiA provides documents regarding specifications, especially cable specifi-
cations on the Internet under:
