I regularly receive inquiries about converting from SAE J1708/J1587 to SAE J1939. Most often, the goal is to bridge old and new technologies—for example, connecting a modern J1939-based dashboard to a legacy J1708-based diesel engine. There are other scenarios, but this one comes up frequently. The logical next step is to look for a protocol gateway that connects both systems—and yes, such gateways do exist, including one we offer. However, two major challenges should be clearly understood before moving forward.

First, SAE J1939 and SAE J1708/J1587 are fundamentally incompatible—not just in terms of hardware (CAN bus vs. RS-485), which could be solved with a hardware adapter and firmware, but in how they define, structure, and transmit data. There is no simple one-to-one mapping between parameters. Second, while I specialize in SAE J1939 (and have basic knowledge of J1708/J1587), I’m not an expert in dashboard-to-engine integrations. Likewise, the engineers involved in such integrations often lack deep knowledge of these protocols, especially which PGNs and PIDs are required to make the system function correctly. This isn’t a criticism—these are complex, multidisciplinary projects.

While J1939/J1708 gateways are available, they only convert a limited set of parameters. That means you must know exactly which PGNs and PIDs your application requires. Identifying the correct parameters can be daunting: diesel engines may support hundreds of them, and the dashboard typically needs only a subset. Determining which parameters to exchange requires thorough knowledge of both the engine’s output and the dashboard’s input expectations.

That’s why I often advise caution. Successfully implementing a solution like our MasterCAN V-Gate (SAE J1708 to J1939 gateway) requires a team or individual who understands the engine, the dashboard, and both communication protocols. If you can find or build that kind of expertise, I offer my sincere admiration—it’s no small feat. But until those requirements are met, I hesitate to sell a product that might technically function but fall short of expectations due to mismatched assumptions. Don’t get me wrong, our gateway is great and does exactly what it promises, but you need to study the documentation before purchasing.

The MasterCAN V-Gate is a high-performance protocol converter developed for commercial vehicle and industrial applications. It enables communication between legacy J1708/J1587 devices and modern SAE J1939 systems, allowing integrators to retrofit or upgrade components such as dashboards, telematics units, or diagnostic tools without completely replacing older engine control systems. The unit reads both J1708 and J1939 traffic, intelligently filters the incoming data, and merges the output into a standardized J1939 format over the CAN bus.

For a deeper technical dive, I recommend reading my post Why J1939 doesn't speak J1708 - Protocols in conflict.