Cables, CAN H and CAN L

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Fig 1: CAN H And CAN L Distributing Signals Within Multiplex Communication Network

Courtesy of VOLVO CARS OF NORTH AMERICA.

The CAN H and CAN L cables must not be confused with HS CAN and LS CAN which are speeds on the Controller area network. CAN H and CAN L are a way of distributing signals within the multiplex communication network.

Communication occurs through two cables. These two cables are paired together. CAN H is always white and CAN L is always green.

The cables are made of copper and are easily identified by the green and white coloring.

The voltage levels for communication occur using differential voltage levels.

The reason for communicating using paired cables and differential voltage levels is that the network becomes less sensitive to interference.

The same message is transferred simultaneously by both cables, but different voltage levels are used.

Binary 1 = 2.5 V on both CAN H and CAN L.
Binary 0 = 4 V on CAN H and 1 V on CAN L.

Average voltage level is 2.5V.