What is a CAN bus?
A Controller Area Network (CAN bus) is a type of network used in vehicles and other industrial systems to allow different devices to communicate with one another. It is a robust, high-speed, and low-cost way of connecting multiple devices and subsystems in a vehicle, such as engine control, transmission control, and airbag systems. The CAN bus uses a two-wire, half-duplex communication protocol and is designed to be tolerant of noise and other interference, making it well-suited for use in harsh environments.
What are the common applications in vehicles?
- Engine control: used to communicate between the engine control module (ECM) and other electronic devices in the vehicle, such as the throttle position sensor, mass airflow sensor, and oxygen sensors.
- Transmission control: used to communicate between the transmission control module (TCM) and other electronic devices in the vehicle, such as the gear position sensor and the speed sensor.
- Chassis control: used to communicate between the electronic stability control (ESC) system, the anti-lock braking system (ABS), and the traction control system (TCS).
- Body control: used to communicate between the body control module (BCM) and other electronic devices in the vehicle, such as the power windows, power mirrors, power seats, and door locks.
- Infotainment: used to communicate between the infotainment system and other electronic devices in the vehicle, such as the audio system, the navigation system, and the climate control system.
- Safety systems: used in advanced driver assistance systems (ADAS) such as lane departure warning, automatic emergency braking, and adaptive cruise control.
What are the different types of CAN bus?
High-Speed CAN (ISO 11898-2) – This is the most common type of CAN bus and is used in automotive and industrial applications. It operates at a data rate of up to 1 Mbps.
- Low-Speed/Fault-Tolerant CAN (ISO 11898-3) – This type of CAN bus is used in applications where the data rate is lower and where fault tolerance is important. It operates at a data rate of up to 125 kbps.
- Medium-Speed CAN (ISO 11898-5) – This type of CAN bus is used in applications where the data rate is between high-speed and low-speed. It operates at a data rate of up to 500 kbps.
- BroadR-Reach (ISO 11898-6) – This type of CAN bus is used in automotive applications and is designed to work over longer distances. It operates at a data rate of up to 1 Mbps.
- Controller Area Network (CANopen) – This is a higher-layer protocol that is built on top of the CAN bus. It is commonly used in industrial and medical applications.
- DeviceNet – This is a proprietary CAN bus protocol that is used in industrial and automation applications. It is developed by Allen-Bradley.
- SAE J1939 – This is a CAN bus protocol that is used in heavy-duty vehicles and other industrial applications. It is developed by the Society of Automotive Engineers.