CANopen interface
50
AMS 335
i
Leuze electronic
9
CANopen interface
9.1
General information on CANopen
9.1.1
Topology
Figure 9.1:
Bus topology
The CAN bus is a serial 2-wire bus system to which all participants are connected in parallel
(i.e., using short drop lines). To avoid reflections, the bus must be terminated with a termi-
nating resistor of 120ohm at each end of the trunk line. Terminating resistors are also
required for very short trunk line cable lengths.
If the AMS 335
i
is the last participant in the trunk line, the trunk line can be terminated via
the M12 bus OUT connection. For this purpose, Leuze electronic offers an M12 terminating
resistor, see chapter 11 "Type overview and accessories".
9.1.2
Bus line (trunk line)
For CAN, the maximum cable length of the trunk line is predominantly limited by the signal
propagation time. The multi-master bus-access process (arbitration) requires that the
signals are present virtually simultaneously at all nodes/participants. Therefore, the cable
length of the trunk cable must be adapted to the baud rate.
Termintator
Trunk Line
Tap
Termintator
Drop
Line
Baud rate
Bus length
1Mbit/s
< 20m
800kbit/s
< 50m
500kbit/s
< 100m
250kbit/s
< 250m
125kbit/s
< 500m
50kbit/s
< 1000m
20kbit/s
< 2500m
