CAN is an abbreviation for ‘controller area network’ and is essentially similar to a computer network whereby individual computers communicate with each other. The ‘bus’ is a subsystem which allows data or power to be transferred between various control units or controlled components. A bus can logically connect several components over the same set of wires.

A single pair of wires (referred to as ‘twisted pairs!’) is sufficient as the means of transferring data as voltage. This makes the wiring very easy at the build process and because CAN bus is now used in such huge volumes, the manufacturing process is far more economical than conventional wiring looms carrying voltage and signals individually to each component.

The diagnosis of faults with CAN bus wiring requires specialist diagnostic equipment in order to capture the data. A standard garage oscilloscope is too slow to display a true picture of data transfer. CAN bus was developed originally (by Bosch) with automotive applications in mind, this technology is now seen in almost any engineering requiring integration of controlled components.

An example of CAN bus in operation is an electric window on a modern car. The window motor has an integrated control unit or mini computer, information is sent to it via the CAN bus network. All the data is carried along twisted pairs of wires. Data is shared with other systems on the car, for example the operation of the window integrating with the alarm or remote central locking.