Maximum Cable Length On The Can-Bus - IRIS Net UCC1 Mode D'emploi

Baud Rate
500 kbit/s
250 kbit/s
125 kbit/s
62,5 kbit/s
20 kbit/s
10 kbit/s
The use of repeaters is generally recommended when a network's bus length exceeds 1000 m.

6.3 Maximum Cable Length on the CAN-Bus

According to the ISO 11898-2 standard, CAN-bus data transfer cabling has to be carried out using
Twisted-Pair cables with or without shielding providing a characteristic impedance of 120 Ω. Both ends of
a CAN-network have to be terminated with 120 Ω termination plugs.
The maximum bus length depends on the actual data transfer rate, which kind of data transfer cable
is used and the total number of participants on the bus. The following table shows the most essential
coherencies for CAN-networks consisting of up to 64 participants:
Bus Length
Length-Related
0 ... 40 m
40 ... 300 m
300 ... 600 m
600 ... 1000 m
To reduce the load for the interface driver and therefore also reducing the voltage drop between the two
**
cable ends, using higher impedance termination than the specified 120 Ω is recommended for networks
with increased cable length and many nodes on the CAN-bus.
The following table is for estimating the necessary cable diameter in relation to the length and the amount
of participants on the bus:
Bus Length
100 m
250 m
500 m
Bus Length
100 m
250 m
500 m
1000 m
2500 m
5000 m
Data Transfer Cable
Cable Diameter
Resistance
0,25 ... 0,34 mm
< 70 mΩ/m
AWG23, AWG22
0,34 ... 0,6 mm
< 60 mΩ/m
AWG22, AWG20
0, 5 ... 0,6 mm
< 40 mΩ/m
0,75 ... 0,8 mm
< 26 mΩ/m
32
0,25 mm respectively AWG24 0,34 mm
2
0,34 mm respectively AWG22 0,5 mm
2
0,75 mm respectively AWG18 0,75 mm
2
Termination
2
2
2
150 ... 300 Ω
AWG20
2
150 ... 300 Ω
AWG18
Number of Units on the CAN-bus
respectively AWG22 0,34 mm
2
respectively AWG20
2
respectively AWG18 1,0 mm
2
25
Data Transfer Rate
124 Ω 1000 kbit/s for 40 m
127 Ω 500 kbit/s for 100 m
100 kbit/s for 500 m
*
62,5 kbit/s for 1000 m
*
64
0,5 mm
Max.
100
respectively AWG22
2
respectively AWG20
2
respectively AWG17
2