What is CAN bus and why is it so important?

We’ve talked about the potential impact of IoT technologies before, and the various ways access to the cloud is shaping hardware design and deployment. But there’s another aspect of system communication that’s just as important to the future of these increasingly complex technologies; CAN bus.

The way devices, sensors, and systems communicate locally is as vital a consideration for hardware manufacturers, providers, and integrators as the way information is delivered to the cloud. While there are a slew of communication protocols and methods available to enable one system to “talk” directly with another, we’ve seen a growing interest in utilizing CAN bus communication for a wide range of industrial applications.

But why has CAN, which stands for Controller Area Network, suddenly become such an appealing industrial computing option? What are the inherent advantages of utilizing this particular communication method in embedded systems?

What is CAN Bus?

CAN bus is a message-based protocol allowing individual systems, devices, and controllers within a network to communicate. In general, a bus is a multi-node communication system that transfers data between components.  A Controller Area Network allows for robust, low-latency, data transfer between sensors and compute units in a system. For instance, OnLogic has worked with clients to equip farming equipment like combine harvesters and other complex pieces of machinery with CAN-capable hardware, enabling the various equipment components to efficiently and effectively relay information to each other.

Following its introduction in the mid 1980’s, CAN bus communication has evolved well beyond the automotive industry where it was first widely adopted. Before CAN bus gained popularity, vehicle wiring harnesses could contain miles of wire, with bundles of wires required to carry various signals to and from interconnected vehicle systems. In contrast, CAN bus utilizes a high-speed (25kbps – 1Mbps) twisted pair wiring system, greatly reducing the amount of wire necessary to allow system components to communicate.

While CAN is still a widely-utilized option in modern in-vehicle computers, like OnLogic’s Karbon Series, CAN bus is now also being implemented in a wide range of embedded and industrial applications, from assembly lines and medical machinery, to building automation and access control installations.

Pictured above is OnLogic’s Karbon 800 series.

What are the benefits of CAN bus?

Integrated CAN bus communication offers a number of advantages for industrial PC users, including:

• Latency – CAN message arbitration rules ensure the highest priority message will be sent first when multiple messages are being sent simultaneously to and from connected devices, sensors, and  actuators.

• Flexibility – Because of its paired-down, single cable, two-wire structure, CAN bus offers enhanced installation and maintenance flexibility. CAN-connected systems not only contain significantly less wire, making them easier to install, but adding new components to a system requires far less development while also greatly reducing complications in diagnosing and addressing signal problems.

• Reliability –Thanks to its twisted pair wiring and differential signaling, CAN is far less sensitive to electromagnetic interference than other protocols, CAN communication also requires fewer cables and connectors, drastically cutting down on points of failure.

• Cost – The lower hardware costs and minimal signal processing requirements make CAN an ideal solution for embedded applications requiring multi-processor communication on a budget.

How is CAN bus used in industrial computing?

In an automated industrial installation, CAN bus is most commonly used as part of a distributed control system, connecting vital systems that may be spread throughout a facility. Generally a Human Machine Interface (HMI) allows the operator to interact with the system. From there programmable logic controllers (PLCs) relay those commands through the CAN bus interface to the sensors, actuators, motors, or other mechanical systems that carry out the desired action.

CAN is often found in use on production lines in manufacturing environments, allowing operators and equipment to effectively communicate at each step of the assembly process. Building automation is another area where the speed, low cost, and ease of installation have made CAN bus communication a popular choice to connect access control, security, and environmental systems.

The future of CAN bus communication

As the Internet of Things continues to grow and encompass more and more complex systems, standardizing the way each component communicates with the next will be vital in ensuring compatibility, expandability, and installation longevity. Here at OnLogic we’re working with clients to implement CAN bus communication in a wide range of custom embedded systems and we continue to see a bright future for the technology, particularly in manufacturing environments and in modern building automation installations.

Note: This post was originally posted on July 10, 2014. It was updated on July 10, 2022.