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.