X10 (industry standard)
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 home automation network technology and remains the most widely available[citation needed].
[1] 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.
[1] When calculator integrated circuit prices started to fall, Pico refocused on commercial products rather than plain ICs.
Software for the interface runs on the Commodore 64, Apple II, classic Mac OS, MS-DOS, and Microsoft Windows.
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.
The relatively high-frequency carrier wave carrying the signal cannot pass through a power transformer or across the phases of a multiphase system.
Many X10 protocol charts represent this start code as "1110", but it is important to realize that is in terms of zero crossings, not data bits.
To allow for wireless keypads, remote switches, motion sensors, et cetera, an RF protocol is also defined.
The devices available using the radio protocol include: Depending on the load that is to be controlled, different modules must be used.
Lamp modules are almost silent in operation, and generally rated to control loads ranging from approximately 60 to 500 watts.
As a result, older Appliance modules may fail to work with, for example, a very low load such as a 5W LED table lamp.
If local dimming is offered, holding down the push button will cause the lamp to cycle through its brightness range.
Higher end modules have more advanced features such as programmable on levels, customizable fade rates, the ability to transmit commands when used (referred to as 2-way devices), and scene support.
There are sensor modules that sense and report temperature, light, infrared, motion, or contact openings and closures.
Device modules include thermostats, audible alarms and controllers for low voltage switches.
Units are also available that use passive infrared motion detectors or photocells to turn lights on and off based on external conditions.
Finally, there are very sophisticated units are available that can be fully programmed and/or controlled with a piece of software called Active Home, such as the CM11A serial interface.
Control programs are available for computers running Microsoft Windows, Apple's Macintosh, Linux and FreeBSD operating systems.
Users can arm and disarm their system via several different remote controls that also use a coded RF signal to ensure security.
When an alarm is triggered the console will make an outbound telephone call with a recorded message.
ioBridge can be used to translate the X10 protocol to a web service API via the X10 PSC04 Powerline Interface Module.
One problem with X10 is excessive attenuation of signals between the two live conductors in the 3-wire 120/240 volt system used in typical North American residential construction.
Often, there's simply no reliable path to allow the X10 signals to propagate from one transformer leg wire to the other; this failure may come and go as large 240 volt devices such as stoves or dryers are turned on and off.
Typically, the capacitors used on the inputs to these power supplies short the X10 signal from line to neutral, suppressing any hope of X10 control on the circuit near that device.
If two X10 signals are transmitted at the same time they may collide or interleave, leading to commands that either cannot be decoded or that trigger incorrect operations.
The standard X10 power line and RF protocols lack support for encryption, and can only address 256 devices.
Unfiltered power line signals from close neighbors using the same X10 device addresses may interfere with each other.
