graphic 4

SAEJ1939

SAE J1939 is the CANbus standard used for communication and diagnostics in many vehicle engines in the USA.

STW has developed several functions to easily handle SAE J1939 messages and to send commands back to the engine by using these same protocols.

SAE J1939 uses the 29-bit extended identifiers available in CANbus transmissions, as opposed to the 11-bit standard identifiers normally used.

SAE J1939 defines an index called the Parameter Group Number or PGN, which is embedded in the message's 29-bit identifier. A PGN identifies a message's function and associated data into a wide range of predefined groups. Parameters such as engine RPM or temperature can easliy be accessed by capturing messages with the associated PGN. A range of PGNs (00FF00h - 00FFFFh) is also reserved for proprietary use, allowing a user to add his or her own messages into the already predefined communication structure.