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2.5 Other J1939 Based Protocols
Per definition, SAE J1939 provides serial data communications between microprocessor systems (also called Electronic Control Units - ECU) in any kind of heavy duty vehicles. The messages exchanged between these units can be data such as vehicle road speed, torque control message from the transmission to the engine, oil temperature, and many more.
SAE J1939 and its companion documents have quickly become the accepted industry standard of choice for off-highway machines. It was all too natural that organizations and manufacturers in the agricultural, military and marine industries, rather than re-inventing the wheel, adopted the proven combination of physical layer, Controller Area Network (CAN), and J1939 as the higher layer protocol for vehicles. However, it is in the specific nature of agricultural and military as well as marine applications that slight modifications, including a name change, were necessary.
These “new” protocols are[1]:
Ø ISO 11783 (a.k.a. ISOBUS) – Agricultural Industry
Ø MilCAN – Military Applications
Ø NMEA 2000 – Marine Applications
[1] Note by the author: While information on NMEA 2000 and especially MilCAN is easily available, documentation of the ISO 11783 standard is “protected” by excessive price tags. One cannot deny the standardization organization’s objective to produce revenues, but one also needs to seriously question their marketing expertise.
