Leuze electronic MA 235i Operating Instructions Manual page 20

Device description
The CAN bus is a serial 2-wire bus system to which all participants are connected in paral-
lel (i.e., using short stub cables). To avoid reflections, the bus must be terminated with a
terminating resistor of 120ohm at each end of the trunk line. Terminating resistors are also
required for very short trunk line cable lengths.
If the MA 235i
the M12 bus OUT connection. For this purpose, Leuze electronic offers an M12 terminat-
ing resistor, see chapter 14 "Type overview and accessories".
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 sig-
nals are present virtually simultaneously at all nodes/participants. Therefore, the cable
length of the trunk cable must be adapted to the baud rate.
Baud rate
1Mbit/s
800kbit/s
500kbit/s
250kbit/s
125kbit/s
50kbit/s
20kbit/s
Stub cables (drop lines)
If possible, stub cables should be avoided because they cause signal reflections as a mat-
ter of principle. Generally, the reflections caused by stub cables are not critical, however, if
the following stub cable lengths are not exceeded.
Baud rate
1Mbit/s
800kbit/s
500kbit/s
250kbit/s
125kbit/s
50kbit/s
20kbit/s
Attention!
Stub cables must not be fitted with terminating resistors. If the MA
stub cable, the M12 bus OUT connection must not be terminated.
18
is the last participant in the trunk line, the trunk line can be terminated via
Length of stub cables
Bus length
< 20m
< 50m
< 100m
< 250m
< 500m
< 1000m
< 2500m
< 1m
< 1m
< 1m
< 10m
< 20m
< 50m
< 50m
MA 235i
Total length of all stub cables
< 5m
< 25m
< 25m
< 50m
< 100m
< 250m
< 250m
235i is integrated into a
Leuze electronic