CANbedded

Some information that must be transferred over the CAN bus does not fit into individual data frames because the data length exceeds 8 bytes. In this case, the sender must divide up the data into a number of CAN messages with the same identifier. Additional information is necessary for the recipient to put the data back together again. This is taken care of by a transport protocol in accordance with ISO 15765-2:

• Segmentation and recording of data that is greater than the basic data link layer.
• Control of the data flow of individual messages.
• Error detection.

The transport protocol according to ISO 15765-2 was harmonized with the Unacknowledged Segmented Data Transfer (USDT), which was specified in the OSEK-COM standard (according to version 2.1). This transport protocol is used by many automobile manufacturers, but is not the only standard in existence. There are also specific solutions of Volkswagen (VWTP) and Bosch (MCNet).