LIN frame
The data frame of the LIN bus is relatively simple and consists of the LIN header with the synchronization mechanism, identifier field, data field and the checksum.
The first data fields of the LIN header are used for the synchronization of the LIN slaves. For this purpose a 13 bit long 0 level is sent as Start of Frame, which indicates to the slaves the start of a new data frame. This is followed by the Sync field with five 1-0 sequences, of which the slaves use the negative signal edge for clock synchronization.
Since the LIN protocol works without source and destination addresses, the identification information of the individual ECUs is transmitted in the Identifier field. The data field, also called message identifier, consists of 6 identifier bits and 2 parity bits and is therefore much smaller than that of the CAN bus. The identifier field is followed by the data field, which can consist of 1 byte to 8 bytes. The data field starts with the least significant bit( LSB). The checksum field concludes the LIN data frame. The modulo-256 sum over all data bytes is formed as the checksum.