The answer is as follows: The three elements of the CAN bus communication protocol include:
1. Physical layer: CAN bus uses twisted pair wire as transmission medium, using differential signal transmission technology, with strong anti-interference ability, long transmission distance and other characteristics.
2. Data link layer: CAN bus uses frame format for data transmission, including standard frame and extended frame formats. The standard frame contains 11-bit identifiers, and the extended frame contains 29-bit identifiers.
3. Application layer: The CAN bus application layer protocol can be customized according to specific application requirements, including data transmission format, data content and data processing methods. Common application layer protocols include CANopen and J1939.
The CAN protocol includes the transport layer, data link layer and physical layer of OSI reference model.