The data is carried on the CAN bus as a voltage difference between the
two signal lines. If both lines are at the same voltage, the signal is a
recessive bit. If the CAN_H line is higher than the CAN_L line by 0.9V,
the signal line is a dominant bit.
Immunity to Ground Noise
The CAN bus does not use the ground as
reference point for these two signal lines. Therefore the CAN bus transmissions lines are immune to any
ground noise typically present in automotive applications.
Immunity to Electromagnetic Filed
The signals on the two CAN lines will both be subject to the same
electromagnetic filed level. Therefore no differences in voltages between
the two lines should become relevant under
Using Twisted Pair Wires for Differential Signal Lines
Bad connectors are almost guaranteed to present an impedance discontinuity,
and hence will cause reflections. Transmission line stubs of any length are also a source of
reflections, longer the stub, the worse the impact of the reflections on lower data rate signals. Reflections are bad because they can cause destructive interference that can corrupt any transmitted data.