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Message Transfer
- All messages on CAN bus are sent in fixed formats.
- When the bus (communication line) is free, any unit connected to the bus may start to transmit a message.
- If two or more units start to transmit messages at the same time, these messages are prioritized using the identifier.
- The identifier does not indicate the destination of the message, but it signifies message priority for bus access.
- If two or more units start to transmit messages at the same time, bitwise (smallest-unit) arbitration is performed over the identifiers carried by the messages. The unit that has won the arbitration as carrying a higher-priority message continues to send the message while the unit that has a lower priority stops sending the message, and starts sending the message again after waiting for a while.