CAN means Controller Area Network (ISO 11898 international standard). It is a serial bus system especially suited for networking "intelligent" devices as well as sensors and actuators and works with multi-master capabilities. Several CAN nodes can request the bus simultaneously.
One of the outstanding features is its high transmission reliability. The CAN controller registers a stations error and evaluates them statistically in oder to take appropriate measures. These may extend to disconnecting the CAN node producing the errors.
In CAN networks no addressing of subscribers or stations in the conventional sense is needed but prioritized messages are transmitted. A transmitter sends his messages to all CAN nodes. Each device decides whether they should process the message or not. The decision is made on the basis of the identifier received. The identifier also determines the priority of the message.
The relative simplicity of the CAN protocol makes applications programming relatively simple. Low-cost controller CAN chips have been around since 1989 and today more than 25 CAN protocol controller chips are available.
The CAN serial bus system, originally developed for use in automobiles, is used in most of European passenger cars, trucks and off-road vehicles.
Each CAN message can transmit from 0 to 8 bytes of user information. But it can transmit longer data information by using segmentation. For networks up to 40 meters the maximum transmission rate is specified as 1 Mbit/s. For longer distances the data rate is reduced, for instance for transmissions up to 500 meters: 125 kbit/s and for 1 km: 50 kbit/s.
The CAN bus is used by the German loudspeaker manufacturer d&b for their amplifier control system. Here the CAN-Bus is connected by daisy-chain to every amplifier's CAN port and fed to a PC computer by a CAN-USB Interface. For larger networks, a CAN to Ethernet Interface can be used (EtherCAN CI manufactured by EMS-Wuensche). The Ethernet network connects the CAN bus to the control PC.