As industries such as agriculture, construction, and mining advance in intelligent technology, traditional machinery and vehicles are being revitalized through the integration of smart solutions. Among these solutions, the complete vehicle solutions offered by OEMs (Original Equipment Manufacturers) often strike a balance between stability and communication efficiency.
However, retrofit solutions for vehicles, which were not part of the initial vehicle design, face challenges such as communication instability. The CAN bus (Controller Area Network), as the mainstream protocol for in-vehicle communication, plays a crucial role in both OEM and retrofit scenarios, particularly in the standardization of communication.
Today, we will focus on the core metric in CAN bus development and application—the standard requirements and testing methods for the load rate.
CAN Bus Overview and Load Rate Standards
The CAN bus is widely used in fields with high safety requirements such as vehicles, aviation, and healthcare. As an open, multi-point communication protocol for low-level control networks, it provides powerful data transmission capabilities for various high-performance devices. When testing CAN bus systems, we first need to specify the baud rate and latency, and validate the product’s compliance by testing the maximum load rate.
01. Definition of Baud Rate and Load Rate
The baud rate refers to the number of signal units transmitted per unit of time, representing the rate at which effective data signals modulate the carrier. The higher the baud rate, the faster the transmission. CAN bus supports various baud rates, with 250kbps and 500kbps being the most common. Among these, 500kbps is the standard configuration for most vehicle applications.
Load rate, on the other hand, is a key indicator of device performance and is critical for evaluating network performance and avoiding communication bottlenecks. In practical applications, it is recommended that the CAN bus load rate remains below 30% under normal conditions and does not exceed 60% during occasional peak usage. A load rate that is too high may lead to data loss or communication lag, affecting system stability.
02. Standard Requirements and Testing Methods
For retrofit in-vehicle smart products, considering the different demands of OEM and retrofit scenarios, Congping Technology proposes that for products operating at 250kbps and 500kbps baud rates, retrofit products must meet the requirement of a 60% load rate without frame loss. Additionally, the send and receive latency must meet customer needs, as excessive latency can impact load rate validation.
Here are our testing methods:
- Set the baud rate: We set the CAN bus baud rate to 250kbps and 500kbps, with two transmission channels.
- Simulation testing: Using simulation tools, we test whether CAN communication can meet the standard requirement of a load rate exceeding 60% without frame loss.
- Stress testing: We conduct stress tests on multiple similar products. The results indicate that most similar products on the market achieve a maximum load rate of around 40% at 500kbps with two transmission channels.
03. Achievements from Congping Technology
Thanks to advanced technology, Congping has achieved stable operation of the 500kbps CAN bus with two channels under load rates as high as 85%, with no packet loss. The average results from our stress tests exceed the 60% standard.
CANBus load rate test equipment
Additionally, our SoC-based CAN bus solution achieves an average send/receive latency of under 6ms, demonstrating low latency and high load capacity. This ensures stable communication and the safe, reliable operation of the system, even in scenarios involving instantaneous high loads or processing large volumes of data.
Waveform diagram during CANBus load rate test
04. Ongoing Research and Future Development
We are committed to further research into CAN communication technology to continually improve product performance, meeting the needs of our clients in real-world applications. Choosing Congping Technology's industrial vehicle-mounted tablets ensures you experience industry-leading CAN communication performance, guaranteeing system safety and stability.
CANBus data processing flow chart
About Congping Technology
Founded on January 29, 2018, Congping Technology focuses on the intelligent transformation of agricultural, engineering, and logistics machinery. By serving thousands of industry clients, Congping provides professional hardware and software solutions for the intelligent evolution of machines, striving for the full smart development of machinery.
