Correct Wiring of Electrically Isolated CAN Networks
CPCI-CAN/200
Hardware Manual Doc.-Nr.: C.2035.21/ Rev. 2.2
Page 19 of 31
7 Correct Wiring of Electrically Isolated
CAN Networks
NOTICE
This chapter applies to CAN networks with bit rates up to 1 Mbit/s.
If you work with higher bit rates, as for example used for CAN FD, the information given in
this chapter must be examined for applicability in each individual case.
For further information refer to the CiA® CAN FD guidelines and recommendations
(
).
For the CAN wiring all applicable rules and regulations (EU, DIN), e.g. regarding electromagnetic
compatibility, security distances, cable cross-section or material, have to be observed.
The flexibility in CAN network design is one of the key strengths of the various extensions and
additional standards like e.g. CANopen, ARINC825, DeviceNet and NMEA2000 that have been built
on the original ISO 11898-2 CAN standard. In using this flexibility comes the responsibility of good
network design and balancing these tradeoffs.
Many CAN organizations and standards have scaled the use of CAN for applications outside the
original ISO 11898. They have made system level tradeoffs for data rate, cable length, and parasitic
loading of the bus.
However, for CAN network design margin must be given for signal loss across the complete system
and cabling, parasitic loadings, network imbalances, ground offsets against earth potential and signal
integrity.
Therefore, the practical maximum number of nodes, bus length and stub length are
typically much lower.
esd has concentrated her recommendations concerning CAN wiring on the specifications of the
ISO 11898-2. Thus, this wiring hints forgoes to describe the special features of the derived standards
CANopen, ARINC825, DeviceNet and NMEA2000.
The consistent compliance to ISO 11898-2 offers significant advantages:
●
Durable operation due to well proven design specifications
●
Minimizing potential failures due to sufficient margin to physical limits
●
Trouble-free maintenance during future network modifications or during fault diagnostics
due to lack of exceptions
Of course, reliable networks can be designed according the specifications of CANopen, ARINC825,
DeviceNet and NMEA2000,
however it must be observed that it is strictly not recommended to
mix the wiring guidelines of the various specifications!
7.1 Standards concerning CAN Wiring
