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. By sharing sensor information with each other, it saves on additional plugs and wiring. It provides the path for modules to share different sensor information, like vehicle speed and other data 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 modules according to speed. Today's wires are twisted pair and often shielded to prevent RFI and MFI interference.
These networks 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. This prevents collisions on the network, and allows signals from modules like the ABS controller a higher priority than modules like the power seat module.