J1939 to J1708 cable: a bridge for the transition of commercial vehicle communication protocols

J1939 to J1708 cable: a bridge for the transition of commercial vehicle communication protocols

In the field of commercial vehicle communication, SAE J1939 and J1708, as two mainstream protocols, have coexisted for a long time. Although J1939 has become a universal standard for heavy vehicles such as trucks, buses, and construction machinery due to its high speed of 250kbps, 29 bit extended frames, and powerful network management capabilities, some older devices still rely on J1708 and RS-485 physical layers. In this context, the J1939 to J1708 cable, as a key hardware for protocol conversion, plays an irreplaceable role in device compatibility, data migration, and system upgrades.

Technical adaptation: Conversion from high-speed CAN to low-speed serial

J1939 is based on the CAN 2.0B protocol, using a 29 bit identifier and extended frame structure, supporting real-time communication between multiple nodes; J1708 is based on the RS-485 bus and transmits 21 byte messages at a rate of 9600bps. The conversion cable requires bidirectional data parsing through a built-in protocol stack: on the one hand, the extended frame of J1939 is decomposed into the MID+data+checksum format of J1708, and on the other hand, the serial data of J1708 is reassembled into the CAN frame of J1939.

Application scenario: compatibility with old devices and smooth system transition

After sales maintenance market: Many repair shops still use scanning tools based on J1708, which can avoid equipment obsolescence costs by converting cables.

Mixed protocol fleet management: Some logistics companies operate both new and old vehicle models simultaneously, and the conversion cable can provide a unified data collection interface.

Industrial equipment renovation: In the field of agricultural machinery, converting cables can achieve data exchange between old and new control systems, reducing renovation cycles and costs.

The J1939 to J1708 cable, as a key tool during the transition period of commercial vehicle communication protocols, provides a feasible solution for the interconnection of old equipment and modern systems with its low cost and high reliability. With the iteration of technology, its application will gradually focus on specific scenarios, and protocol unification and standardization remain the long-term goals of the industry.