Data Frame

In a CAN network, useful data are transmitted by data frames. A data frame can transport a maximum of 8 useful bytes. To have the useful data accepted by the proper receiver, a whole series of additional pieces of information are needed. First, transmission of the SOF (Start of Frame) produces synchronism between senders and receivers. The identifier that follows establishes the relationship between sender and receiver.

After the two bits "RTR" and "IDE" and a reserved bit, the DLC (Data Length Code) indicates the number of useful bytes. After the data field, the sender transmits a checksum to protect the data frame. After the delimiter bit, all CAN nodes must acknowledge the data frame either positively or negatively, independent of message filtering. The transmission is ended by the EOF (End of Frame).