What is ISO 15765 vs J1939

Introduction:

ISO 15765 and J1939 are two widely used protocols in the automotive industry for communication between electronic control units (ECUs) in vehicles. In this article, we will take an in-depth look at these protocols, their differences, and their applications.

ISO 15765: The Basics

ISO 15765 is a standard developed by the International Organization for Standardization (ISO) that defines the diagnostic communication over Controller Area Network (CAN) protocol. It specifies the requirements for a network layer protocol to address the needs of diagnostic systems communicating on a CAN bus. ISO 15765 provides a framework for reliable, secure, and efficient communication between ECUs in vehicles.

J1939

J1939, on the other hand, is a standard developed by the Society of Automotive Engineers (SAE) specifically for heavy-duty commercial vehicles. It defines the communication protocol used for in-vehicle networks, such as trucks and buses. J1939 is based on the CAN protocol and is designed to support the reliable exchange of information between various ECUs in a vehicle.

Differences between ISO 15765 and J1939

While both ISO 15765 and J1939 serve the purpose of facilitating ECU communication, there are some key differences between them. One major difference is their application scope. ISO 15765 is a generic protocol used in various types of vehicles, including passenger cars and light-duty trucks. In contrast, J1939 is primarily used in heavy-duty commercial vehicles.

Another difference lies in their message format. ISO 15765 uses a diagnostic-specific message format, which allows for diagnostic information exchange between ECUs. J1939, on the other hand, defines a parameter group format that enables the transmission of data related to various vehicle systems, such as the engine, transmission, and brakes.

Furthermore, ISO 15765 supports multiple transport protocols, including CAN, Internet Protocol (IP), and others, making it more versatile in terms of communication mediums. In contrast, J1939 typically relies on the CAN protocol for communication, limiting its compatibility with other transport protocols.

Conclusion

Both ISO 15765 and J1939 are important protocols that enable effective communication between ECUs in vehicles. While ISO 15765 provides a general framework applicable to various vehicle types, J1939 specifically targets heavy-duty commercial vehicles. Understanding the differences between these protocols is crucial for automotive engineers, allowing them to select the most suitable protocol for their specific application needs.

Whether it's diagnosing complex issues or ensuring efficient performance, ISO 15765 and J1939 play an integral role in modern vehicle communication systems.