CAN stands for Controller Area Network, a serial BUS system used for connecting devices in systems or sub-systems. The CAN network protocol came about in the mid-80s automotive industry, when the need to control different sub-systems of the vehicle, e.g. motor, steering, signaling, etc., emerged.
The CAN protocol was standardized in ISO 11898, and its use has become increasingly widespread, extending beyond the automotive industry into high-end, heavy-duty machinery for use in construction, materials handling, forestry, and agriculture.
How does CAN work?
CAN communication is best understood in the following way: instead of sending a message from component A to unit B, the message is broadcast. Each component is then able to listen for, collect, and act on information that is relevant for that particular component. The individual component actively listens and only acts when it is addressed.
If an emergency occurs, each individual component can send a relevant warning. In this way, other CAN components can identify the component the emergency call is coming from and take pre-programmed action.
CAN components communicate using a protocol, which can be compared to a language. The different protocols on the market are adapted to the applications in which they are used, and the devices that are connected by a CAN network are typically sensors, actuators, and other control devices. The CANopen protocol is particularly suitable for mobile applications.
The use of CAN increases the flexibility of a system. One of the most obvious benefits is reduced wiring. A single two-wire bus is all that is needed to connect several CAN devices. This reduces costs, simplifies mechanical design, and makes it easier to insert additional devices into a system.
The use of CAN-enabled devices is rapidly growing in heavy-duty on-highway and off-highway vehicles and machines with electro-hydraulic controls. However, before using CAN for CAN's sake, it is important to know the advantages of CAN-enabled devices.
CAN is an extremely robust and cost-effective way to control complex machines with extended wiring compared to analog solutions.
The simplified wiring and reduced number of IO modules provides the biggest advantages in high-end machines with many controls that require extensive wiring. The fact that additional features can be added to the machines at a very nominal cost is highly appreciated by both machine owners and operators.
One of the key CAN benefits, like any network, is that it makes it possible to share resources and information between devices. This means that one sensor can easily be shared between two or more controllers, or two controllers may share information about their respective subsystems. Instead of using point-to-point communications, any device on a CAN network can communicate with any other.
In this way, the system diagnostics can be centralized and simplified. As a single device can access all devices on the CAN, it is possible to centralize diagnostic tools to a single access point. The real-time availability of data supports condition monitoring and predictive maintenance. During operation, it is easy for the operator to locate a failure and fix the problem, significantly reducing downtime on equipment.
The logging and recording capabilities of CAN components tie in with advanced telematic solutions, supporting remote upgrades and services, efficiency, fleet management, and operator safety.
Machine manufacturers can reduce development costs by using CAN-based components. Using CAN-enabled components, design engineers can build complex control applications without point-to-point wiring. The result is fewer I/O modules, cables, and connectors, reducing potential harness failures.
The simplified system design and easy integration of the components into the overall system accelerates time to market and saves design time and money.
CAN products are 'open' and allow customization. This means that design engineers can use the exact features needed for a specific application.
The use of CAN also simplifies redesign processes. Manufacturers may pick what is best for their requirements, swap devices between CAN networks, and retrofit machines with additional modules.
To meet the growing demand for CAN-based components, Danfoss has launched two new CAN transmitters: DST P92C (pressure) and DST T92C (temperature) for mobile hydraulics.
The modern fieldbus technology reduces wiring costs and provides new opportunities in condition monitoring and predictive maintenance.
The standardized CAN communication allows compatibility with devices and systems from different manufacturers.