Controller Area Network (CAN)
The controller area network or CAN allows a vehicle's onboard computers to communicate with each other on a high-speed bus. Sharing sensor information saves on additional plugs and wiring. It provides a path for modules to share sensor information, like vehicle speed with other modules. It's considered a high-speed network, with type A, type B, and type C networks, all operating at different speeds.
A Class C CAN operates at speeds of 1 Mbps. A Class B is low speed at 125 Kbps, and Class A at 10 Kbps. As one would imagine, these three networks connect different systems according to speed. Today's wires are twisted pair and often shielded to prevent RFI and MFI interference.
They use electrical pulses to communicate on a serial line. It's a series of 0's and 1's that dictate the type, origin, and importance of a signal. The frame of information is broken down to start, identifier, and priority sections. The priority of a signal is indicated by a 0 or a 1. A signal with a priority of 0 has a higher priority than a signal with a 1. It prevents collisions on the network and allows signals from critical modules like the ABS controller to have a higher priority than modules like the power seat module.