The J1939 transport protocol is build upon the CAN 2.0b protocol and provides the transfer of serial data communication between electronic control units (ECUs) in heavy-duty vehicles. The J1939 is also a set of SAE (Society of Automotive Engineers) standards which allow the transfer of CAN messages bigger than 8 bytes. Since the CAN network cannot be used to transfer more than 8 bytes, the need for a more capable protocol emerged and in 2004 the J1939 was introduced.
SAE J1939 and its companion documents have quickly become the accepted industry standard and the vehicle network of choice for off-highway machines in applications such as construction, material handling, mass transportation, forestry machines, agricultural machinery, maritime and military applications.