What is CAN? (Controller Area Network)

The controller area network (CAN) is a serial communication protocol developed by the German company Bosch. The word CAN may remind many people of automobiles. This protocol was completed in 1985 and was first adopted in mass-produced cars in 1990. Then, in 1994, the International Organization for Standardization (ISO) standardized it as ISO 11898 and ISO 11519. Today, the protocol is adopted on almost all automobiles. Furthermore, CAN is being utilized in a wide variety of fields, including factory automation (FA).

CAN was originally developed to be utilized within automobiles, but now this technology is utilized at factories, as well as on medical and other worksites. The background behind this technology was the necessity to support an increasing number of electronic control units (ECUs) in parallel with the performance enhancement of automobiles. More complicated control means more I/Os and larger ECUs, and data sharing among multiple ECUs also increases the number of wires. These factors will lead to complicated, heavier automobiles with more components, which will require much higher production costs. A solution for this situation was a CAN serial communication protocol that enables high-speed and reliable communication with a small number of wires.

In addition to CAN, other communication protocols−including the LIN, the FlexRay, and the MOST−are also used in on-board networks. The LIN, which is intended to be used as a CAN subnetwork, is a standard that enables serial communication at a low cost. On the other hand, the FlexRay, which has received attention as a next-generation on-board network, enables faster communication than CAN. While CAN, the LIN, and the FlexRay are mainly used for communication to control engines, the Media Oriented Systems Transport (MOST) is intended for multi-media system communication. As outlined here, there are various communication protocols in addition to CAN.

CAN is classified according to the communication speed into the high-speed CAN “CAN-C,” the low-speed CAN “CAN-B,” etc. Furthermore, the Society of Automotive Engineers (SAE) classifies CAN based on the communication speed as follows.

The importance of CAN protocol lies in its reliability, robustness, simplicity, and effectiveness as a communication protocol between various electronic control units within a vehicle. This reduces the complexity and weight of wiring, improving vehicle performance and enhancing the diagnostic capabilities of the vehicle.

However, CAN protocol is used in industrial settings as well for performing different measurements. For example, KEYENCE’s NR-X Series multi-input data logger or NR-500 multi-input DAQ can process CAN data measurements, which is crucial for vehicle testing, performance analysis, and research and development.

Implementing the CAN communication protocol involves setting up a network of ECUs and sensors connected through a two-wire bus. Each node in the network sends and receives messages based on identifiers that determine message priority. CAN protocols ensure that the highest priority message is transmitted first.

CAN protocol is a message-based protocol that relies on several different types of messages:

• Data Frame: Carries data from the transmitter to the receivers.
• Remote Frame: Requests data from another device.
• Error Frame: Transmitted by any node that detects an error.
• Overload Frame: This indicates that a node is too busy to process further requests.

As stated above, Bosch designed the CAN bus protocol to reduce the wiring inside the vehicle, especially compared to traditional wiring in older vehicles. This is a rather robust system that provides real-time readings and communication complemented with priority-based message arbitration and error messaging and signaling capabilities. The CAN bus is rather flexible, and you can easily add new devices to the network without having to make major changes to the existing system.

FD stands for “Flexible Data RATE,” which is the extension of the original CAN protocol. It supports higher data rate and larger data payloads per frame. These enhancements allow more efficient data transmission, which is convenient considering the increasingly complex and data-intensive systems equipped in modern vehicles.