What is difference between CAN and J1939 ?

Title: What is the Difference Between CAN and J1939? A Comprehensive Analysis

The Controller Area Network (CAN) bus is a widely used standard communication protocol in the automotive industry for communication between electronic control units (ECUs). However, the CAN bus is not the only protocol in use. J1939, a higher-layer protocol, operates on top of the CAN bus and is specifically designed for heavy-duty vehicles such as trucks and buses. In this article, we will explore the differences between the CAN bus and J1939 in detail.

Data Transmission Rates and Capacity:

CAN (Controller Area Network) bus:

The CAN bus is a standard communication protocol that allows microcontrollers and devices to communicate with each other within a vehicle. It was initially developed by Bosch for use in automotive systems but has found applications in various industries. The CAN bus has a maximum data transmission rate of 100 kbps.

J1939:

J1939 is a higher-layer protocol that operates on top of the CAN bus. It provides specific guidelines and rules for communication between heavy-duty vehicles, such as trucks and buses. J1939 is widely adopted in the commercial vehicle industry due to its robustness and reliability.

Differences between CAN Bus and J1939:

Scope:

While both CAN bus and J1939 are related, there are several key differences between them. CAN bus is a general-purpose communication protocol that can be used for various applications beyond automotive, such as industrial automation and medical equipment. J1939, on the other hand, is specifically designed for heavy-duty vehicles and their associated systems.

Data Transmission Rates:

J1939 has a higher data transmission rate than the CAN bus. The maximum data transmission rate of J1939 is 500 kbps, while the CAN bus has a maximum data transmission rate of 100 kbps.

Compatibility:

J1939 is more compatible than the CAN bus. While both protocols are based on the Controller Area Network (CAN) bus, J1939 is a higher-layer protocol that provides more specific guidelines and rules for communication between heavy-duty vehicles.

Implementation:

J1939 has a more extensive implementation than the CAN bus. Implementing J1939 requires a device-level protocol stack, which includes a CAN interface module, a data transfer protocol, and a host interface. On the other hand, implementing the CAN bus protocol requires only a software module that manages the communication between the microcontroller and the CAN bus.

Conclusion:

In conclusion, while both CAN bus and J1939 are related, there are significant differences between them in terms of their features, data transmission rates, and compatibility. J1939 is a higher-layer protocol that provides more specific guidelines and rules for communication between heavy-duty vehicles, while the CAN bus is a general-purpose communication protocol that can be used for various applications beyond automotive. Both protocols have their own advantages and disadvantages, and the choice between them depends on the specific requirements of the application.