Although it is now obsolete, some home automation companies still promote X10 for home automation applications on the web.
What is X10 home automation?
X10 is one of the first home automation technologies developed by Pico Electronics of Glenrothes in Scotland in 1975. X10 became popular because it was one of the few home automation systems that could easily be adapted to existing homes without installing additional cables, thanks to its entry-level quality and pricing.
X10 is an open protocol for communication between home automation devices that mainly uses network wiring for signaling and control, superimposing the signals on the waveform of the sine wave. A further radio-based X10 protocol has also been defined. See below for more details.
Many X10 home automation devices are plugged into a socket, so you connect the lamps or devices you want to control to the X10 device. Integrated X10 wall switches and ceiling light controllers are also available.
The latest and most advanced home automation technology now offers faster, more reliable and safer communications and control than X10 equipment.
How does the X10 protocol work?
X10 home automation uses your existing electrical wiring to transmit digital data between X10 devices. Bursts of data encoded on a 120 kHz carrier are transmitted during zero crossings of the 50/60 Hz AC waveform, with a single digital bit being transmitted at each zero crossing.
X10 digital data consists of an address and a command that is sent from an X10 controller to an X10-controlled device. More advanced X10 controllers can also poll each other for on/off or level status using the X10 protocol.
Special measures must be taken to allow X10 signals to be transmitted from one phase to another or on split-phase systems if necessary. Coupling capacitors or an X10 active repeater or an X10 signal amplifier and a coupling capacitor are usually used for this purpose.
Care must also be taken to ensure that X10 communications do not leak from house to house along the main wiring, which extends to the street and is common to the houses. To prevent these special inductive X10 filters from attenuating X10 signals as they are transmitted from your home to incoming mains power lines.
What are the limits of the X10 protocol?
X10 communication is slow. Sending a device address and command via X10 takes about 0.75 seconds. This can be problematic in bi-directional switching applications where two parties can unintentionally turn on/off a shared set of lights.
When multiple X10 signals are generated at the same time, they interfere with each other and may prevent them from being received or processed correctly. X10 signals must be individually generated to work reliably, which can be problematic at times in a home with more than one occupant.
Homeowners may experience unreliable load-related X10 communications, where reliability decreases and increases when certain 240V loads such as ovens or hair dryers are turned on or off.
The use of televisions or wireless devices may cause interference with X10 on/off signals, and the installation of EMI noise filters to reduce such interference may also attenuate X10 signals if not specifically designed for X10 installations.
The power supplies of some computer electronics (eg computers, televisions, etc.) may contain EMI suppression capacitors (to help them comply with EMI regulations) which also unintentionally attenuate X10 signals.
Special X10 devices may need to be installed to selectively isolate X10 from these supplies (but not from other parts of your home's electrical installation to which X10 devices may be connected) to avoid this unwanted attenuation of X10 signals. Identifying and isolating the causes of this type of disruption to the operation of an X10 home automation system can be time-consuming and frustrating.