SAE J1939

The SAE J1939 standard defines a standard for the networking and communication of commercial vehicles (including both road vehicles and construction machinery). It focuses primarily on applications involving the chassis and the powertrain.

SAE J1939 is a decentralized multi-master system based on the CAN bus. It exclusively utilizes 29-bit identifiers and a fixed bit rate of 250 kbit/s. Other standards associated with this transport protocol… …are connected are the SAE J1708 bus protocol and the SAE J1587 application layer.

All communication parameters (signals) are managed across four so-called memory pages and grouped into parameter groups (PGs). These are organized into 8-byte structures to enable the most efficient possible data exchange via the CAN bus.

A direct peer-to-peer connection can also be established for the transfer of large amounts of data.

The following transport protocols can be used for the transfer of large amounts of data:

• BAM – Broadcast Announce Message (broadcast to all participants)
• CMDT – Connection Mode Data Transfer (via peer-to-peer to exactly one participant)

The primary standard is SAE J1939. Numerous sub-standards derived from it further define specific use cases and details.