What is the difference between J1939 and CAN-FD

The J1939 and CAN-FD are two widely used protocols in the automotive industry for communication between electronic control units (ECUs). Both protocols are based on the Controller Area Network (CAN) bus, which is a standard communication network in vehicles. However, there are significant differences between J1939 and CAN-FD in terms of their features, data transmission rates, and compatibility. In this article, we will explore these differences in detail.

Data Transmission Rates and Capacity

One of the key differences between J1939 and CAN-FD is their data transmission rates. J1939 operates at a fixed data rate of 250 kilobits per second (Kbps), while CAN-FD introduces flexible data rates that can range from 125 Kbps up to 10 megabits per second (Mbps). This means that CAN-FD has much higher bandwidth capacity, allowing for faster data transfer and better real-time control.

Message Length and Addressing

In terms of message length and addressing, J1939 and CAN-FD also differ. J1939 defines a maximum message length of 1785 bytes, whereas CAN-FD allows for much larger message lengths, up to 64 kilobytes (KB). This allows for more extensive and complex data exchange between ECUs using CAN-FD. Furthermore, J1939 uses an addressing scheme based on source addresses, destination addresses, and group functions, while CAN-FD employs a more flexible and simplified addressing scheme.

Compatibility and Adoption

Another important aspect to consider is the compatibility and adoption status of J1939 and CAN-FD. J1939 is a well-established protocol that has been widely used in the automotive industry for many years. It is supported by various manufacturers and has a large installed base of ECUs that are compliant with the J1939 standard. On the other hand, CAN-FD is a relatively newer protocol that offers improved performance but has not gained widespread adoption yet. While some manufacturers have started to implement CAN-FD in their new vehicle models, the majority of vehicles still operate using the J1939 protocol.

In conclusion, J1939 and CAN-FD are two communication protocols used in the automotive industry based on the CAN bus. While J1939 has been the predominant protocol for many years, CAN-FD introduces higher data transmission rates and larger message lengths. However, due to its newer status, CAN-FD is not as widely adopted as J1939. As technology evolves, it will be interesting to see if CAN-FD becomes the new standard or if J1939 continues to dominate the industry.