Bus terminators are electrical devices attached to the end points of a bus network to prevent the signals from reflecting off the end of the transmission line. They do this by supplying a load equal to the impedance of the cable.
Bus networks are connected in a chain formation by a single wire or series of wire segments. Once each component has detected a signal, the signal is absorbed by the bus terminator allowing other components to place their signals on the cable. Without the bus terminator, a signal placed on a wire by a component would bounce back and forth between the ends of the cable, preventing other cables from signaling.
Bus terminators are used in ethernet networks, small computer system interfaces, dummy loads and control area networks. If you are looking for a device that can provide bidirectional input or output control and can be used in either digital or analogue devices consider a bus transceiver