CAN bus (Controller Area Network) is a vehicle bus standard that allows devices such as motor controllers, sensors, and other ECU’s (electronic control unit) to communicate with each other. CAN bus acts as the nervous system of the vehicle.
CANopen is a high-level protocol originally designed for motion-oriented machine control systems. While CANopen was originally designed for motion control it’s now used in a wide variety of applications and every vehicle today is equipped with CAN bus.
Benefits of CANopen
CANopen is a standardized protocol (ISO 11898) making implementation of new devices straightforward, and CANopen devices can easily be configured to fit the application specific needs. The standardized format allows tools to configure and handle the CANopen device properly. For example, units, resolution and filtering can be set on individual devices and designers can use off-the-shelf tools, protocols and reuse application software.
CANopen is an robust protocol with fail safe measures such as heartbeat protocol, boot-up protocol and timeout monitoring with configurable settings. This also enable error monitoring of the signal line thus electromagnetic interference or other disturbances on the cable can be detected. Compared to analog signals where it’s impossible to detect failures when the signal is within its defined limits. Thus, diagnostics can be done more accurate during operation and reduce downtime.
CANopen also reduces the amount of cable needed for auxiliary devices. A CANopen network uses a common twisted pair cable to transmit signals and up to 127 devices (1 master and up to 126 slaves, in CAN language called Nodes) can connect to the same bus cable. A CANopen network is flexible and can be configured with modules for easy adaptation to different needs, for example if a large number of sensors are used for data collection the sensors can be daisy chained with one single cable instead of using one cable per sensor.