Written by Patricia Skinner
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J1939-based networks are based on the CAN protocol and connect electronic control units within a truck and trailer system. The purpose of these computer/truck interface systems is to monitor the engine and other parts of heavy vehicles. The benefits to be had from such an automated system include increased vehicle flexibility and reliability, product standardization, parts economy, self-diagnostics, elimination of the need for long connection wires, and log and record capabilities.

Development of J1939

The Society of Automotive Engineers (SAE) began developing J1939 as a CAN-based application during the 1990s. In 1998, they published the specifications for their new system, including engine transmission and break message definitions. This system is specifically for diesel engine applications and was intended to replace the earlier J1587/J1708.

In essence, the improvements that are incorporated into the J1939 system are that it is an industry-specific application with combination layers for that industry alone. J1587/J1708 is not specific for the truck and trailer system alone. J1939 systems have now developed and progressed into a family of their own.

There are systems for agricultural and forestry vehicles, which also conform to ISO standards. There are also systems for marine navigation applications. Several additional CAN Open interface profiles have been developed by CiA (CAN in Automation) specifically for J1939-based networks. These gateways conform to ISO 11992-2 and ISO 11992-3. The entire CAN Open family incorporates a framework for gateways that are compatible with J1939/71.

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