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9.2. CEBus

The effort for a Consumer Electronics Bus standard was initiated during a Washington, DC, hotel room meeting, sponsored by Electronics Industries Alliance and attended by 12 members representing 12 different companies in April of 1984. Similar to that of X-10, the original goal of CEBus was to develop an infrared remote control standard. Not surprisingly, some parts of the CEBus standards are used for residential and industrial control applications. During 1986, GE's Homenet was selected as the foundation of CEBus protocol. During 1988, an early version of the CEBus Power Line physical layer was proposed using the 1-Kbps Amplitude Shift Keying (ASK) technique. Some techniques for transmission over other media, such as Twisted Pair (TP) and Coaxial Cable (CX), were also proposed thereafter. The current version of the CEBus PL physical layer is based on Intellon's spread spectrum technique proposed during 1991. A control application language was adapted during 1998. CEBus standards were developed to interconnect consumer electronic devices within a home and to link these devices to services provided by external resources at a very economical cost. Details of CEBus standards are described in EIA-600 documents [1–3].

Two components of these CEBus standards have achieved some limited success in real-world applications. The first is the CEBus PL physical layer and the second is the CAL. The CEBus PL physical layer can transmit data packets at about 10 Kbps using a special type of spread spectrum technique. Each CEBus PL packet contains sender and receiver addresses. The CEBus protocol uses a peer-to-peer communications model so that any node on the network has access to the media at any time. To avoid data collisions, it uses a Carrier Sense Multiple Access/Collision Detection and Resolution (CSMA/CDCR) protocol. CAL allows devices to communicate commands and status requests between each other using a common command syntax and vocabulary. CAL defines various electronic device functional subunits as contexts. For example, the audio control of a TV, a stereo, a CD player, or a VCR is a CAL context. Each context is further broken down into objects, which represent various control functions of the context (e.g., volume, bass, treble, or mute functions). Finally, objects are defined by a set of instance variables that specify the operation of the function of the object, such as the default or current setting of the volume object.


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