CAN bus

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CAN bus

(Controller Area Network bus) A rugged, digital serial bus designed for industrial environments. Introduced by Bosch in the mid-1980s for in-vehicle communications, it is used in myriad applications including factory automation, building automation, aircraft and aerospace as well as in cars, trucks and buses. CAN bus replaced bulky wiring harnesses with a two-wire differential cable (the two wires carry inverted voltages to decrease interference).

CAN provides services at layers 1 and 2 of the OSI model and uses a broadcast method for placing frames on the wire somewhat similar to Ethernet. Bus distance is based on speed, ranging from a maximum of 40 meters at 1 Mbps to a maximum of six kilometers at 10 Kbps. At speeds up to 125 Kbps, CAN provides fault tolerance. If one of the two wires is cut or shorted, the other keeps transmitting.

In a vehicle, both low- and high-speed CAN buses are used. For example, window, lighting and seat control only need low speeds, while engine, cruise control and antilock brakes require high speeds. Two or three CAN buses may be used in a vehicle; for example, a high-speed bus may be dedicated only for safety (air bags, seat belt tensioners, etc.).

The Bus Hampers After-Market Installations
The CAN bus has made it challenging to add certain after-market products to a vehicle. In older cars, there were discrete wires for everything, but CAN bus signals are digital frames that have to be analyzed to determine their purpose. For example, taxi meters and many GPS navigation systems need to monitor vehicle speed. If speed pulse is no longer available as a discrete wire, a CAN bus interface, such as the CANM8-NAV unit from Bridgewater Electronics (www.bridgewater-electronics.co.uk), can convert speed pulse frames to a speed pulse signal.

CANopen and CiA
Introduced in 1995, CANopen is a high-level application layer protocol that provides services for processes, data and network management. The international organization that governs the CANopen protocol is CAN in Automation (CiA). For more information, visit www.can-cia.de. See automotive systems and automotive Ethernet.
References in periodicals archive ?
Several plastics equipment suppliers actively promoted CANbus as a feature of their products at NPE in Chicago this past June.
As a result, CANbus data sets such as Engine Speed, Actual Fuel Used, Actual Engine Torque, Engine Temperature, Accelerator Pedal Position or Brake Switch can be collected from ANY commercial vehicles.
The system includes the GX-60 touch screen graphical display and four 360 degree tilt sensor all connected via a CANBus configuration.
BATCHCONTROL communicates via CANbus, a high-speed bus protocol for high-speed communication requirements, thereby greatly simplifying machine design with valve controls done the BATCHCONTROL itself.
The twisted pair of wires that comprise the CANbus circuitry hook the module up to a central processing module.
The MEMS devices have sufficient resolution and accuracy for many applications, and it is possible to multiplex a large number of them using conventional CANbus or similar high-speed multiplexing technology (so that electrical interference can be minimized by converting to digital signals locally along an array).
The ekrPro series is built upon a modular open architecture that uses CANbus communications protocol.
The line is built upon a modular open architecture utilizing CANbus communications protocol.
Additional interfaces include four high-speed serial ports, CANBUS, SPI, I2C and parallel I/O.
The MGS1600 has a uniquely long list connectivity options: the tape position information can be output in numerical format on the sensor's RS232, USB, CANbus, Analog or PWM ports.
0 interfaces and eight serial ports with multiple RS232, RS422, or RS485 configurations as well as two CANbus and eight single-ended, buffered LVTTL discrete digital I/O ports.
0 ports, two LANs, one CANbus and two PCI Express Mini Card slots for wireless network connections.