The SAE J1939 committee updates the digital annex periodically. The J1939DA supplements the document series specifying the CAN Bus network for use in heavy-duty vehicles. It provides definitions for the physical, the transport, and the application layer. Additional specifications include network management and functional safety protocol, which is still under development.
The digital annex comprises mainly the Parameter Group Number (PGN) definitions or references to documents, in which they are specified in detail. References to ISO documents have been updated and corrected. PGs are identified uniquely by means of the PG number (PGN). The spreadsheet also contains the Suspect Parameter (SP) definitions including its number (SPN). It also provides information about assigned manufacturer names and global source addresses.
Six years after its initial release, SAE has also updated the J1939 top-level document. It provides a general overview of the SAE J1939 network and describes the subordinate document structure. This document includes definitions of terms and abbreviations, which are used among the various SAE J1939 subordinate documents.
A Comprehensible Guide to J1939
SAE J1939 has become the accepted industry standard and the vehicle network technology of choice for off-highway machines in applications such as construction, material handling, and forestry machines. J1939 is a higher-layer protocol based on Controller Area Network (CAN). It 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.
The information in this book is based on two documents of the SAE J1939 Standards Collection: J1939/21 - Data Link Layer J1939/81 - Network Management A Comprehensible Guide to J1939 is the first work on J1939 besides the SAE J1939 standards collection. It provides profound information on the J1939 message format and network management combined with a high level of readability.