The following is an excerpt from by Wilfried Voss.SAE J1939 is a very ingeniously designedprotocol that takes a resourceful advantage of the CAN 29-Bit messageidentifier. Rather than relying on a myriad of protocol functions, SAE J1939uses predefined parameter tables, which keeps the actual protocol on a comprehensiblelevel. However, these parameter tables (Parameter Groups) are also the biggeststumbling block when it comes to implementing the protocol into an embeddedsolution (ECU).Parameters groups are, for instance,engine temperature, which includes coolant temperature, fuel temperature, oiltemperature, etc.
2013 Edition, September 2013. SAE J1939-71 (Complete Document ) 2012 Edition, May 2012. SAE J1939-71. SAE J1939-71 Vehicle Application Layer is the SAE J1939 reference document for the conventions and notations that specify parameter placement in PGN data fields, the conventions for ASCII parameters, and conventions for PGN transmission.