X10 is a protocol for communication among electronic devices used for home automation (domotics). It primarily uses power line wiring for signaling and control, where the signals involve brief radio frequency bursts representing digital information. A wireless radio-based protocol transport is also defined.
X10 was developed in 1975 by Pico Electronics of Glenrothes, Scotland, in order to allow remote control of home devices and appliances. It was the first general purpose domotic network technology and remains the most widely available.
Although a number of higher-bandwidth alternatives exist, X10 remains popular in the home environment with millions of units in use worldwide, and inexpensive availability of new components.
History
In 1970, a group of engineers started a company in Glenrothes, Scotland called Pico Electronics. The company developed the first single chip calculator. When calculator integrated circuit prices started to fall, Pico refocused on commercial products rather than plain ICs.
In 1974, the Pico engineers jointly developed an LP record turntable, the ADC Accutrac 4000, with Birmingham Sound Reproducers, at the time the largest manufacturer of record changers in the world. It could be programmed to play selected tracks, and could be operated by a remote control using ultrasound signals, which sparked the idea of remote control for lights and appliances. By 1975, the X10 project was conceived, so named because it was the tenth project. In 1978, X10 products started to appear in RadioShack and Sears stores. Together with BSR a partnership was formed, with the name X10 Ltd. At that time the system consisted of a 16 channel command console, a lamp module, and an appliance module. Soon after came the wall switch module and the first X10 timer.
In the 1980s, the CP-290 computer interface was released. Software for the interface runs on the Commodore 64, Apple II, Macintosh, MS-DOS, and MS-Windows.
In 1985, BSR went out of business, and X10 (USA) Inc. was formed. In the early 1990s, the consumer market was divided into two main categories, the ultra-high-end with a budget at US$100,000 and the mass market with budgets at US$2,000 to US$35,000. CEBus (1984) and LonWorks (1991) were attempts to improve reliability and replace X10.
Brands
X10 components are sold under a variety of brand names:
X10 Powerhouse
X10 Pro
X10 Activehome
Radio Shack Plug 'n Power
Leviton Central Control System (CCS) Leviton Decora Electronic Controls Sears Home Control System Stanley LightMaker Stanley Homelink Black & Decker Freewire IBM Home Director RCA Home Control GE Homeminder Advanced Control Technologies (ACT) Magnavox Home Security NuTone Schlage Smarthome Safety 1st HAL HomeSeer
Power line carrier control overview
Household electrical wiring which powers lights and appliances is used to send digital data between X10 devices. This data is encoded onto a 120 kHz carrier which is transmitted as bursts during the relatively quiet zero crossings of the 50 or 60 Hz AC alternating current waveform. One bit is transmitted at each zero crossing.
The digital data consists of an address and a command sent from a controller to a controlled device. More advanced controllers can also query equally advanced devices to respond with their status. This status may be as simple as "off" or "on", or the current dimming level, or even the temperature or other sensor reading. Devices usually plug into the wall where a lamp, television, or other household appliance plugs in; however some built-in controllers are also available for wall switches and ceiling fixtures.
The relatively high-frequency carrier wave carrying the signal cannot pass through a power transformer or across the phases of a multiphase system. For split phase systems, the signal can be passively coupled from leg-to-leg using a passive capacitor, but for three phase systems or where the capacitor provides insufficient coupling, an active X10 repeater can be used. To allow signals to be coupled across phases and still match each phase's zero crossing point, each bit is transmitted three times in each half cycle, offset by 1/6 cycle.
It may also be desirable to block X10 signals from leaving the local area so, for example, the X10 controls in one house do not interfere with the X10 controls in a neighboring house. In this situation, inductive filters can be used to attenuate the X10 signals coming into or going out of the local area.