What is CAN bus? How does it work?


The automotive industry has witnessed remarkable advancements in recent years, with vehicles becoming more sophisticated and connected. Behind the scenes, a communication technology known as Controller Area Network (CAN) bus plays a crucial role in enabling seamless interaction between various components within a vehicle. In this article, we will delve into the world of CAN bus, exploring its functionality, applications, and how it differs from On-Board Diagnostics (OBD). Additionally, we will discuss the remarkable capabilities offered by the Alotcer AR7091 Vehicle LTE Gateway in vehicle diagnostics, leveraging the power of CAN bus technology.

How CAN bus works

CAN bus, at its core, is a robust and reliable communication protocol that allows various electronic components within a vehicle to exchange information efficiently. It employs a two-wire serial communication scheme, typically utilizing twisted pair cables, to establish a networked system.

The CAN bus architecture consists of nodes or electronic control units (ECUs) distributed throughout the vehicle, each equipped with a microcontroller and a CAN transceiver. These nodes communicate with each other by transmitting and receiving messages over the shared bus.

The communication on a CAN bus follows a non-destructive arbitration scheme, ensuring that messages from different ECUs do not collide. Each message transmitted on the bus carries a unique identifier, prioritizing the data based on their importance. This identifier, along with the message payload, enables seamless and organized data exchange between the participating ECUs.

What is CAN bus? Exploring the Communication Backbone of Modern Vehicles

What is CAN bus?

CAN bus, short for Controller Area Network bus, is a widely used communication protocol in the automotive industry. It acts as the backbone of communication between various electronic components within a vehicle, enabling them to share information and cooperate efficiently.

The primary goal of CAN bus is to ensure reliable and robust communication in the presence of multiple nodes and potential electromagnetic interference. It achieves this by utilizing differential signaling and implementing error detection and correction mechanisms.

CAN bus vs. OBD

While CAN bus and On-Board Diagnostics (OBD) are related concepts in the automotive realm, they serve different purposes and operate at different levels within a vehicle.

What is OBD?

On-Board Diagnostics (OBD) refers to the standardized system used to monitor and diagnose the performance of a vehicle’s engine and other subsystems. It provides access to real-time data, fault codes, and various sensor readings, allowing technicians to diagnose and troubleshoot issues effectively.

OBD systems were initially introduced to comply with emission regulations, but they have evolved to encompass a broader range of diagnostic capabilities. The OBD-II standard, which is widely used today, requires vehicles to have a standardized diagnostic connector and support specific communication protocols.

What’s the difference between CAN bus and OBD?

CAN bus and OBD are distinct but interconnected components within a vehicle’s communication and diagnostic infrastructure. Here are the key differences between them:

Functionality: CAN bus is the communication protocol that facilitates data exchange between various electronic components in a vehicle, whereas OBD focuses specifically on diagnostic capabilities, providing access to engine and subsystem information.

Scope: CAN bus operates at a lower level, enabling communication between ECUs and transmitting data such as sensor readings, control signals, and status information. OBD, on the other hand, is an application layer that utilizes the CAN bus or other communication protocols to retrieve diagnostic information for troubleshooting and maintenance purposes.

Standardization: CAN bus is a communication protocol with specific specifications governing its physical and data link layers. OBD, on the other hand, encompasses a range of diagnostic standards, with OBD-II being the most widely adopted in modern vehicles.

Access and Control: While CAN bus communication is primarily utilized by ECUs within the vehicle, OBD provides access to diagnostic data for technicians, allowing them to read and interpret the information using specialized diagnostic tools.

What is special about CAN bus?

CAN bus offers several unique features that make it particularly suited for automotive applications:

Robustness: CAN bus was designed to withstand the demanding automotive environment, where factors like electromagnetic interference, noise, and temperature variations are common. Its differential signaling and error detection mechanisms ensure reliable data transmission and reception.

Scalability: CAN bus supports a multi-master architecture, allowing multiple ECUs to communicate simultaneously without conflicts. This scalability enables the integration of additional functionalities and components into the vehicle’s network.

Prioritization: CAN bus uses message identifiers to prioritize data transmission, ensuring that critical information is delivered promptly. This prioritization mechanism helps manage the flow of information and optimize performance within the network.

Low Cost: CAN bus utilizes a simple two-wire architecture, which reduces the complexity and cost of wiring harnesses within the vehicle. This cost-effective design makes it a popular choice for automotive manufacturers.

Applications of CAN bus

CAN bus finds extensive applications in modern vehicles, playing a crucial role in enabling various functionalities and systems. Some notable applications include:

Engine Control: CAN bus allows communication between the engine control unit, transmission control unit, and other relevant components, facilitating precise control of engine parameters and optimizing performance.

Body Control: CAN bus enables communication between ECUs responsible for functions like lighting, HVAC (Heating, Ventilation, and Air Conditioning), door locks, and window controls, ensuring coordinated operation and user convenience.

Safety Systems: CAN bus connects safety-related systems such as anti-lock braking systems (ABS), traction control, and electronic stability control, allowing them to exchange information and respond effectively in critical situations.

Infotainment: CAN bus facilitates the integration of infotainment systems, including audio, navigation, and connectivity features. It enables communication between the head unit, display, audio components, and other entertainment-related ECUs.

Advanced Driver Assistance Systems (ADAS): CAN bus plays a vital role in ADAS functionalities such as adaptive cruise control, lane-keeping assistance, and collision warning systems. It allows the exchange of sensor data and control signals between the relevant ECUs.

Telematics: CAN bus integration with a vehicle LTE gateway, such as the Alotcer AR7091, enables connectivity and data exchange with external networks. This connectivity enables features like remote diagnostics, over-the-air updates, and vehicle tracking.

The Application of Alotcer AR7091 in Vehicle Diagnostics

The Alotcer AR7091 Vehicle LTE Gateway is a powerful device that enhances vehicle diagnostics capabilities by leveraging the potential of CAN bus technology. With its advanced features and integration capabilities, the AR7091 offers numerous benefits in the field of vehicle diagnostics. Some notable features and applications include:

Real-Time Data Monitoring: The AR7091 can connect to the CAN bus network, allowing it to retrieve real-time sensor data, diagnostic trouble codes (DTCs), and other critical information from the vehicle’s ECUs. This data can be accessed remotely by technicians, enabling them to monitor vehicle performance and diagnose issues efficiently.

Remote Diagnostics: The AR7091, when integrated with a comprehensive diagnostic platform, enables remote diagnostics of the vehicle. Technicians can remotely access the vehicle’s CAN bus data, analyze it, and identify potential problems or malfunctions. This capability minimizes the need for physical access to the vehicle, saving time and resources.

Over-the-Air Updates: By utilizing the connectivity provided by the AR7091, manufacturers can deliver software updates and patches to the vehicle’s ECUs through the CAN bus network. This feature ensures that vehicles stay up to date with the latest improvements and bug fixes, enhancing performance, and addressing potential security vulnerabilities.

Fleet Management: The AR7091 can be integrated into fleet management systems, providing real-time monitoring and diagnostics capabilities for an entire fleet of vehicles. This integration allows fleet managers to track vehicle performance, identify maintenance needs, and optimize the overall efficiency of their fleet.

Vehicle Tracking and Recovery: The AR7091’s integration with the CAN bus network enables vehicle tracking and recovery in the event of theft or unauthorized use. By accessing the vehicle’s location data and status information, authorities can locate and recover stolen vehicles more effectively.


Q: What is CAN bus used for?

CAN bus is used for enabling communication between various electronic components within a vehicle, facilitating data exchange, and coordination of functionalities such as engine control, safety systems, infotainment, and more.

Q: How does CAN bus work?

CAN bus works by establishing a networked system of nodes or ECUs connected through a shared bus. Messages carrying unique identifiers are transmitted and received over the bus, allowing for organized and efficient data exchange between the ECUs.

Q: What is CAN bus protocol?

CAN bus protocol refers to the set of specifications and rules that govern the communication scheme and data transmission on the CAN bus. It defines the physical and data link layers, including message structure, identifier format, error detection, and signaling mechanisms.


CAN bus is a fundamental technology that forms the communication backbone of modern vehicles. It enables seamless interaction between electronic components, supporting critical functionalities in areas such as engine control, safety systems, infotainment, and more.