How CAN Works

At its core, CAN is a two-wire, multi-master network protocol that allows microcontrollers and devices to communicate without a host computer. In practice, this means that individual electronic components - such as sensors, actuators, and controllers - can send and receive messages to each other directly over just two shared wires. Each device listens to the network and can transmit information when the line is free, making the system both efficient and resilient.

This setup eliminates the need for a central computer to coordinate communication, which reduces complexity and potential failure points.

For example, in a modern vehicle, the engine control unit (ECU) can talk to the transmission, the brakes, and even the dashboard indicators independently, ensuring real-time coordination and faster system response.

The simplicity of the wiring, combined with the robustness of the protocol, makes CAN ideal for environments where reliability, speed, and minimal wiring are critical.

Essential CAN Terminology

When discussing CAN, there are a few terms and concepts that are important to familiarize yourself with. These include:

• CAN Bus - The physical two-wire communication line (CAN High and CAN Low) over which devices communicate. All devices in the system are connected to this shared communication medium.
• Node - Any device connected to the CAN bus is called a node. A node could be a sensor, actuator, microcontroller, or control unit.
• ECU (Electronic Control Unit) - a dedicated embedded computer that controls specific functions - such as engine performance, braking, or lighting. On a CAN network, each ECU acts as a node, sending and receiving messages to coordinate with other ECUs without needing a central controller.
• Transceiver - The hardware interface between a device and the CAN bus. The transceiver transmits and receives electrical signals on the CAN lines.
• CAN Controller - The part of a microcontroller or peripheral device that formats and interprets CAN messages according to protocol rules. Some microcontrollers have built-in CAN controllers; others use external ICs.
• Message Frame (CAN Frame) - The data link layer frame sent over the CAN bus. It includes:
  • Identifier (ID) – A unique number assigned to each packet type that determines the packet priority. Lower numbers receive higher priority during bus arbitration.
  • Data Field – Up to 8 bytes of payload (64 bytes in CAN FD).
  • Control and Cyclic Redundancy Check (CRC) Fields – For managing communication and checking errors.
• Arbitration - The process by which multiple devices attempt to send messages at the same time. The device with the highest-priority message (lowest ID) wins and transmits first.
• Bit Stuffing - A technique used to maintain synchronization by inserting extra bits into the data stream if needed. This helps keep signal integrity across the network.
• Baud Rate - The speed at which data is transmitted (typically 125 kbps to 1 Mbps for standard CAN). All nodes must operate at the same baud rate.
• Termination Resistor - A 120-ohm resistor placed at each end of the CAN bus to prevent signal reflections and ensure proper communication.
• Bus Load - The percentage of time the CAN bus is occupied with communication. Keeping bus load within safe limits (usually <50–70%>) ensures reliable operation.
• Error Frame - A special frame sent when a node detects an error. The error frame helps maintain integrity by informing other nodes of issues.

Pros and Cons of CAN

CAN has become a widely adopted communication protocol in many industries due to its simplicity, robustness, and efficiency. Like any technology, it offers distinct advantages as well as certain limitations depending on the application. Understanding the pros and cons of CAN helps engineers and system designers determine whether it's the right fit for their specific needs.

Advantages of CAN

Disadvantages of CAN

Robust and Reliable
CAN uses differential signaling (CAN High and CAN Low), which makes it highly resistant to electrical noise and interference, making it ideal for harsh environments like vehicles and factories.

Limited Data Payload
Standard CAN frames only allow up to 8 bytes of data per message (64 bytes with CAN FD), which may be insufficient for data-heavy applications.

Simple and Cost-Effective Wiring
CAN requires only two wires for communication across all devices, reducing wiring complexity and cost compared to point-to-point systems.

Speed vs Distance Trade-off
The higher the baud rate, the shorter the maximum bus length. For example, 1 Mbps is typically limited to about 40 meters.

Multi-Master Architecture
Any node can initiate communication, enabling decentralized control and eliminating the need for a central host or master.

No Built-In Security
CAN does not natively include encryption or authentication, making it vulnerable to spoofing or malicious injection if physical access is gained.

Built-In Error Detection
Features like CRC checks, acknowledgment bits, and error frames help identify and handle faults automatically, improving system safety and reliability.

Complex Message Decoding
Messages are raw binary values with identifiers, so interpreting them often requires manufacturer-specific documentation or reverse-engineering.

Efficient Arbitration Mechanism
The priority-based message arbitration ensures that critical messages are transmitted first without collisions, maintaining real-time performance.

Requires Termination and Balanced Wiring
For proper communication, termination resistors and careful wiring practices are necessary. Miswiring or poor grounding can lead to silent failures or corrupted data.

For a deeper dive into real-world use cases and detailed comparisons, check out this post: CAN Network Protocol: Pros, Cons, Applications.

Understanding CAN Variants: Standard, Extended, and CAN FD

As CAN technology has evolved to meet the growing demands of different applications, several variations have emerged, each offering unique capabilities. Two key distinctions to understand are the difference between Standard and Extended CAN, which relates to how messages are identified, and Classic CAN vs CAN FD, which affects data capacity and speed. These variations impact everything from network design to device compatibility and performance.

Standard CAN vs Extended CAN

While many systems use what's known as Standard CAN, there's also a variation called Extended CAN designed for more complex networks. Both use the same fundamental communication method and can coexist on the same bus, provided nodes support both formats. Extended CAN allows for a much larger range of message identifiers—making it ideal for systems with many devices or data types - like commercial vehicles or industrial networks.

In contrast, Standard CAN is simpler and more efficient for smaller networks with fewer nodes. Understanding the difference between these two formats ensures your system is designed with the right balance of performance, scalability, and message clarity.

Classic CAN vs CAN FD

CAN FD (Flexible Data-rate) is an advanced version of the original CAN protocol, created to meet the growing demand for faster, higher-capacity data communication in modern vehicles and industrial systems.

Unlike Classic CAN, which is limited to 8 bytes per message and a fixed data rate, CAN FD supports payloads up to 64 bytes and allows for increased bit rates during the data phase.

It also includes additional control bits—such as EDL (Extended Data Length) and BRS (Bit Rate Switch)—to enable these enhancements.

CAN FD improves overall bandwidth and efficiency without changing the physical layer - meaning it can operate on existing CAN hardware with upgraded controllers. This makes it ideal for applications requiring larger data transfers, like advanced driver-assistance systems (ADAS), over-the-air updates, or sensor fusion.

While Classic CAN remains useful for simpler control messages, CAN FD is designed to future-proof CAN networks for more complex and data-intensive environments.

CAN Higher-Layer Protocol Fundamentals

Although CAN provides a robust physical and data-link layer with efficient arbitration and error handling, it doesn't prescribe how application-level data should be structured or interpreted. This lack of standardization can pose challenges when building scalable or interoperable systems involving multiple vendors or complex coordination.

To bridge this gap, higher-layer protocols are often implemented on top of CAN to define message formats, device profiles, and network management behaviors. These protocols – CANopen, J1939, UDS, OBD2, and others – extend CAN's utility by enabling structured, deterministic communication tailored to specific domains and application requirements.

Let's take a closer look at some of the most widely used protocols, how they work, where they're used, and what sets them apart.

To explore how these protocols function in real-world applications, check out our in-depth webinar CAN Higher Layer Protocols - J1939, CANopen, UDS or dive into practical insights in our companion guide, CAN Higher Layer Protocols Q&A.

Industrial Applications of CAN

CAN is widely used across a range of industries. Engineers, integrators, and system designers rely on it every day to enable reliable communication between devices in complex systems. Here are some of the most common environments where CAN can be found:

Aerospace & Defense
Supports deterministic, fault-tolerant data exchange in drones, aircraft, and military vehicles.

Automotive
Enables real-time control and diagnostics across systems like engines, brakes, lighting, and infotainment.
5 Reasons CAN is the King of Automotive Communication Protocols

Agriculture
Ensures interoperability and coordination in smart farming systems like tractors and harvesters.
CAN on the Farm - 6 Key Applications

Building Automation
Integrates HVAC, lighting, elevators, and security systems in smart buildings.

Heavy Machinery
Withstands harsh environments; ideal for mobile equipment requiring reliable communication and diagnostics.

Industrial Automation
Connects PLCs, sensors, and actuators for reliable, real-time factory floor communication.

Marine & Boating
Supports engine control, navigation, and diagnostics in marine electronics.

Medical Devices
Provides dependable communication for critical systems like infusion pumps and imaging machines.

Municipal Infrastructure
Reliable control of distributed systems in harsh outdoor environments

Rail & Transportation
Manages control and diagnostic systems in trains, including doors, brakes, and propulsion units

Robotics
Coordinates sensors, motor drivers, and control systems in collaborative and industrial robots.

CAN Software

CAN software is the interface that brings your CAN hardware to life, enabling configuration, communication, debugging, and analysis across the entire system. It plays a critical role in both development and deployment, offering visibility into traffic, control over messages, and tools for automation.

If you're using a USB-to-CAN adapter or a PCI-based interface, most solutions include free basic software, such as Peak's PCAN-Basic and PCAN View, to help you get started.

For more advanced capabilities like real-time monitoring, filtering, scripting, and simulation, software such as PCAN-Explorer 6 offers a robust platform, and a free 30-day trial to explore its full potential.

Not sure where to begin? Watch our introductory webinar to see PCAN-Explorer in action.

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Custom CAN Solutions Built for Your Application

Custom CAN options are ideal when off-the-shelf products fall short, and you need a solution that aligns precisely with your requirements or environment.

Whether it's a custom connector layout, specialized firmware, enclosure design, or cloud connectivity, Grid Connect can tailor every element to fit your exact use case.

With deep experience in both CAN and networking technologies, our team provides the flexibility and engineering support needed to create reliable, scalable, and fully certified custom CAN solutions – delivered on time and built to last.

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