Technical Articles

What are the key differences between CAN FD and CAN C?

CAN (Controller Area Network) is a widely used communication protocol in the automotive industry. It enables different components of a vehicle to communicate with each other effectively. Over time, CAN has evolved to introduce new versions such as CAN FD (Flexible Data-Rate) and CAN C (Classical). In this article, we will explore the key differences between CAN FD and CAN C.

CAN FD: Enhanced Data Transfer

CAN FD, as the name implies, offers enhanced data transfer capabilities compared to its predecessor CAN C. The main difference lies in the increased data rate. While CAN C supports a maximum data rate of 1 Mbps (megabits per second), CAN FD can achieve data rates up to 15 Mbps. This higher speed allows for more efficient and faster communication between various electronic control units (ECUs) within a vehicle.

In addition to the higher data rate, CAN FD also introduces larger data frames. CAN C frames have a maximum payload of 8 bytes, whereas CAN FD frames can carry payloads of up to 64 bytes. This expanded frame size enables the transmission of more data in a single message, reducing the overhead associated with sending multiple messages.

CAN C: Reliability and Compatibility

While CAN FD offers improved speed and efficiency, CAN C remains an essential part of the automotive communication landscape due to its reliability and compatibility. CAN C has been established and widely adopted for many years, making it highly reliable and trusted in automotive applications.

CAN C operates at a fixed baud rate, typically set at 500 Kbps (kilobits per second). This fixed rate ensures consistent and predictable communication, which is crucial for safety-critical systems in vehicles. Additionally, many existing ECUs and automotive components are designed to work specifically with CAN C, making it the preferred choice in certain applications.

Compatibility Challenges

The introduction of CAN FD poses compatibility challenges. While CAN FD controllers can handle both CAN FD and CAN C frames, older CAN C controllers are not compatible with CAN FD frames. This means that systems relying on CAN C may need upgrades or adaptations to take advantage of the benefits offered by CAN FD.

Another challenge is the impact on network architecture. CAN FD frames have larger payloads, which can potentially lead to increased bus load. This requires careful consideration of network design and the number of nodes connected to maintain optimal performance.


In summary, the key differences between CAN C and CAN FD lie in their data transfer capabilities, reliability, and compatibility. CAN FD offers higher data rates and larger frame sizes, enabling faster and more efficient communication. However, CAN C remains reliable and widely used, particularly in legacy systems. As the automotive industry continues to evolve, understanding the advantages and challenges of each protocol is crucial for effective communication and system integration.


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