The CAN bus line

Fundamentally only a single-wire cable would be necessary for data transfer. But with such a single-wire bus only a relatively low transmission speed is possible. In addition to this, all stations connected to the single-wire bus must be available to the electrical ground of the vehicle. Therefore a single-wire bus reacts more sensitively to outside electrical glitches.

The CAN bus also exists in a single-wire variation (the single-wire CAN) and is installed by Opel, for example. The LIN bus has only a single data line.
Because of their properties single-wire buses are used in automobiles only as a sub-bus (e.g. for air conditioners or roof electronics).

The CAN bus is significantly more efficient in its twin-wire design and therefore is used more frequently. Both data lines are twisted together and are therefore less susceptible to outside electrical glitches. An additional shielding (as for example in coaxial cable) is not necessary. Unfortunately no uniform colour coding exists. Therefore both types of wires can have different colours depending on the manufacturer.

 

The two lines are marked as CAN high (CAN-H) and CAN low (CAN-L).