User guide

69
CAN bus cable To meet ISO 11898 you should use a bus cable with a characteristic impedance of
120 Ω. The maximum usable cable length for reliable communication decreases
with increasing transmission speed. As a guide, you can use the following values
which we have measured, but they are not to be taken as assured limits:
Cable data: Characteristic impedance 100-120Ω
Cable capacitance max. 60 nF/km
Lead resistance (loop) 159.8 Ω/km
Cable length, depending on the transmission rate
Lower cable capacitance (max. 30 nF/km) and lower lead resistance (loop,
115 Ω/km) make it possible to achieve greater distances.
(Characteristic impedance 150 ± 5Ω =:> terminating resistor 150 ± 5Ω).
For EMC reasons, the SubD connector housing must fulfill the following conditions:
l metal or metallized housing
l shield connection to housing.
Transmission rate (kBauds) max. cable lenght (m)
1000 20
500 70
250 115
*
6
1
5
9
6
1
5
9
6
1
5
9
6
1
5
9
X6 X6 X6 X6
CANL
CANH
PGND
Shield
CANL
CANH
PGND
Shield
*
* according to line impedance about 120Ω