CAN Communication Protocol

Controller Area Network (CAN) is a communication protocol originally developed by BOSCH in the mid-1980s for the automotive industry. Initially designed to enable data transmission between electronic control units in automobiles, CAN has since been adopted across numerous other sectors including industrial automation, medical devices and shipbuilding like as a reliable communication solution common. CAN offers a range of features that provide a low-cost, efficient, flexible and reliable communication infrastructure.

Key Features of the CAN Protocol

Multi-Master Support

Devices connected to a CAN network can transmit data simultaneously without being bound to a specific order. This means each device has the right to independent data. If multiple devices attempt to transmit at the same time, a priority sequence is established. In the CAN protocol, priority is determined by the message’s ID value. The message with the lowest ID is transmitted first. This mechanism prevents collisions and ensures efficient network management.

Message Transmission and Collision Resolution

CAN provides data transmission in a standardized format. Each message consists of a header, a data field and a control field. When any device begins transmitting data on the network, other devices detect it. If simultaneous transmissions occur, the device with the highest priority is determined by its ID value. This situation prevents collisions and ensures data is transmitted in the correct order. CAN employs the Carrier Sense Multiple Access with Collision Resolution (CSMA/CR) method to enable shared access to the communication medium just.

Flexibility and System Design

In a CAN network, adding or removing any device does not affect the operation of other devices. This makes the CAN protocol exceptionally flexible at the system level. Adding or removing a device requires no changes to the software, hardware or network applications of other devices. This feature provides significant advantages in rapidly evolving sectors such as automotive.

Speed and Performance

CAN offers various speed options for data transmission. All devices on a CAN network must operate at the same transmission speed. As speed increases, the number of connectable devices decreases. The CAN protocol can achieve data transmission rates up to 1 Mbps. However, increasing the number of devices on the network reduces transmission speed, as more devices transmitting data can introduce communication delays.

Error Management and Recovery

The CAN protocol includes mechanisms to detect, error report and recover from errors during communication. Errors can originate from either hardware or software sources. When an error is detected, the device identifying it notifies all other devices and retransmits the data until the error is corrected. This ensures data integrity across the network. Additionally, a device that continuously generates errors is excluded from the network and cannot participate in communication, thereby ensuring healthy operation of the remaining devices.

Connection and Topology

The CAN protocol enables multiple devices to be interconnected on a network. This connection is typically configured in a bus topology. Devices transmit data over two main hat: CAN_H (high) and CAN_L (low). These two lines enable differential transmission of the signal. The CAN protocol provides flexible building scaling based on the number of devices on the network, but a trade-off must be established between the number of devices and transmission speed.

The Importance of Termination Resistors in the CAN Protocol

Termination Resistors

Termination resistors are critical for the proper operation of CAN networks. These resistors are placed at both ends of the network and their primary function is to prevent reflection issues. Reflection occurs when signals are not properly absorbed during transmission and bounce back along the network, causing data loss road. If termination resistors are not correctly installed, these reflections disrupt communication and prevent the network from functioning reliably.

Generally, 120 ohm termination resistors must be installed at both ends place. This prevents any signal reflection and guarantees data transmission accuracy. As the length of the cable used in the network increases, the importance of termination resistors becomes even greater. If these resistors are missing or wrong installed, errors occur in the network and data loss between devices may result.

Termination Resistor Configuration

Proper configuration of termination resistors in the network is essential. Placing 120 ohm resistors at both ends is sufficient for most CAN networks. However, factors such as network topology and length may require additional resistance or alternative configurations. For Long lines and large networks, additional termination resistors may be needed to prevent signal distortion.

The CAN protocol is a reliable and flexible communication infrastructure used across a wide range of industries from automotive to industrial automation. With features such as multi-master support, message prioritization, flexibility and robust error management, CAN delivers high performance and reliability in data transmission. Additionally, properly installed termination resistors prevent data loss and signal reflections, contributing to stable network operation. These characteristics have made the CAN protocol one of the most important communication solutions in modern industries.