Are the electronic devices in your home connected, or are they a collection of isolated electronic islands? To save energy, does your security system adjust the thermostat when you leave the house? Can your home tell you when a visitor is approaching, then automatically turn on the porch lights? Can you use your TV remote to turn off the lights in another room? If you answered "no" to these questions but you'd like to say "yes," you need to learn about home automation technology.
The most common and well-established home automation technology is X10. Since its appearance in the 1970s, X10 has become more refined, more reliable, and less expensive. X10 defines a protocol and electrical specification for sending commands over household AC power lines. In addition to power-line signals, many X10 appliances also support wireless transmission through radio frequencies. X10 doesn't transmit data quickly, but that's not a problem. Transmitting commands such as "turn on the upstairs hall light" or "the outside motion detector is detecting motion" doesn't take many bits.
The X10 protocol can control up to 256 devices in your house, divided into 16 house codes (denoted by the letters A through P) and 16 device codes (numbered 1 through 16). You set each X10 receiver (e.g., a plug-in lamp module or appliance module) to a particular house code and device code, such as A5 or C14. Each electrical device you want to control requires a separate X10 receiver. If you want to control multiple lamps simultaneously, you can set each lamp's receiver to the same house and device code. In most cases, a piece of equipment that transmits X10 signals (e.g., wireless transceiver, remote control, wired keypad) is set to a particular house code and isn't changed. You have plenty of flexibility when using device codes. For example, if you want to control 16 or fewer devices, you can use one house code and a single transceiver with multiple remotes. Or you can set a transceiver and a remote to a separate house code, one for each room of your house.
Getting Started with X10
You can get started with X10 for about $100. For that price, you can set up a system to control a few lights with a remote control or your PC. If you like your initial X10 experience, you can expand the number of X10 devices and build a customized automated home system for $2000 or $3000. When you compare an X10 implementation with a professional installation of high-end automation equipment, which might cost $20,000 or more, X10 seems very price competitive. (For sources of X10 equipment and information, see the sidebar "Exploring X10 Technology," page 21.)
The most common and economical X10 modules are the ones that plug into the wall. To use them, you set the house and device codes by using the selector wheels on the module, plug the module into the wall, then plug the device to be controlled into the module. A limitation of using plug-in modules is that you can't control lights or equipment built directly into your home's wiring. Also, the modules can be unsightly if you use a lot of them.
As an alternative to plug-in modules, you can use X10 controls that replace existing light switches and outlets. These controls are expensive—$20 to $80 per switch—but they provide a built-in custom look to the installation and offer the most flexibility. But before you spend a small fortune replacing all the light switches in your home, make sure that X10 works well for the devices and functions you want to automate. A good place to start is with an X10 combination package that offers a remote control, receiver, PC interface, and one or more modules to control lights and appliances. X10.com sells the ActiveHome kit for about $50. HOPCO sells a similar kit, under the IBM Home Director brand, for $30, and SMARTHOME.COM sells a version with a keychain remote for $80. You can use the handheld universal remote that comes with any of these packages to operate up to 16 X10 devices, as well as most TVs, VCRs, and cable boxes. You might also want to add a wireless motion detector; X10.com sells one under the name Hawkeye. When Hawkeye detects motion, it sends a signal to a wireless transceiver, which transmits an X10 signal over the power line. You can use the X10 signal to control a device directly or have the signal trigger other actions through a PC interface.
Enter the PC
Using a PC increases your home automation options. For example, with a PC as an interface to your X10 controls, you can turn on the lights even if you aren't home. PCs are relatively inexpensive and plentiful, and they offer a variety of flexible hardware and software options. A 200MHz PC can handle most home automation chores; this is a great way to use an otherwise-obsolete system. The X10 PC Interface box, often known by its X10.com part number (CM11a), plugs into a wall outlet and connects to a PC serial port. The interface lets the PC send and receive X10 commands through the power line. Both the ActiveHome and Home Director kits include software that provides basic functionality for controlling the devices in your home. An option lets you download a limited set of instructions into the PC Interface so that the PC doesn't always need to be running.
You'll get the most functionality from X10 devices if you use a program such as HomeSeer Technologies' HomeSeer home automation software, which runs on the PC and uses the X10 PC Interface only for sending and receiving X10 commands. HomeSeer uses an event-driven model that lets you specify a particular event and the action you want to take when that event occurs. The event can be an incoming X10 signal, a particular time of day, or a recurring schedule of times. The action can be to send another X10 command, trigger a sequence of commands, or even run a program on the PC. Using the X10 remote control, for example, you could run an MP3 player on the PC and play your favorite music. If you like to program and want even more control than the event model allows, you can write scripts to perform any action. HomeSeer comes with useful sample scripts—for example, scripts that will retrieve the weather forecast from the Internet and announce the forecast over your PC's speakers.
Beyond Lights and Appliances
You can do even more with home automation if you integrate your system with existing home electronics (e.g., a security system). A typical home security system knows when doors or windows are opened, whether motion is detected in various areas of the house, and whether the system is armed. Many security systems differentiate between arming the system when you're leaving the home and when you're at home, which is another important piece of information you'll want to know when automating your house. For example, the home automation system could set back the thermostat 5 degrees whenever the security alarm is armed and you're leaving the house, saving energy when nobody is home.
One way you can integrate alarm information into home automation is by linking a PC to the alarm panel. For example, NAPCO Security Group's Gemini alarm system lets a PC communicate with the alarm through a serial port. Or you can have the security system control X10 devices directly through their own power-line interface; both NAPCO's Gemini and HAI's Omni series offer this capability. The Omni also integrates thermostat control, which makes it an all-in-one solution for most home automation work.
As you think about automating other devices around the house, you'll probably encounter devices that you can't automate or monitor by turning their AC power on or off. Fortunately, X10 offers several solutions for these situations. One option is the Powerflash module, which has two terminals that you can connect to a switch or a set of magnetic contacts like the ones used in security systems. When the circuit is closed or a low-voltage signal is applied, the Powerflash module sends an X10 ON signal. When the circuit opens again, the Powerflash module sends an OFF signal. For example, by using a magnetic contact on a door, a Powerflash module could send an X10 signal whenever the door was opened or closed.
Another option is the Universal Module, which acts the opposite of a Powerflash module. The Universal Module is a switch X10 signals control. When the Universal Module receives an X10 ON signal, the switch closes and the controlled device operates. When the module receives an OFF signal, the switch opens. You also can use the Universal Module in a "momentary" mode; that is, the module closes the switch for only 2 seconds each time it receives an ON signal. You can use the Universal Module for any type of low-voltage switching application, for example, to control an outdoor sprinkler system or operate low-voltage lighting. You also can use the Universal Module to interface X10 functions to a security system by wiring the module into one of the alarm zones.
The most common X10 problem is phase bridging. Nearly all homes in North America have 220-volt electrical service, which is split into two legs of 110 volts for lighting and electrical outlets. If you put an X10 transmitter on one 110-volt leg and a receiver on a circuit that's on the other 110-volt leg, there might not be a strong enough signal to activate the receiver. You can sometimes work around this problem by moving the transmitter or receiver to another outlet so that the transmitter and receiver will be on the same leg. But if you plan to get serious with X10, your best solution is to install an X10 signal bridge or repeater at the electrical circuit breaker box. These devices cost between $50 and $250, and you should have a licensed electrician install them unless you're comfortable doing your own electrical work.
Another common source of trouble is that people sometimes use an X10 lamp module when they should use an appliance module. Here's my rule: Use a lamp module only for light bulbs. Lamp modules use an electronic switch called a triac, which lets you use X10 signals to dim a light or turn it on or off. However, a lamp module's electronic switch isn't compatible with devices that have motors, transformers, or most other electronics. You can permanently damage some equipment if you plug it into a lamp module. Appliance modules use a mechanical relay to switch the power, so they'll work with anything, including light bulbs. But you'll hear a clicking sound whenever an appliance module switches on or off.
If your neighborhood is full of gadget freaks, you might run into a problem with interference from neighboring homes that also have X10 devices installed. You can receive interference from X10 signals coming in through the power lines, or from the radio signals of a wireless remote control. If you encounter devices that turn on and off on their own—or your neighbors complain about out-of-control X10 devices—try changing the house codes or device codes you're using. Also, some devices might generate noise that blocks X10 signals. You can troubleshoot this problem by unplugging most of your electronics to see whether the X10 device works. If the device works, plug in your electronics one at a time until you find the one that's causing the problem. You can purchase noise filters to solve the problem from most sites that sell X10 equipment.
In the spirit of being prepared, I've described several things that can go wrong. However, don't let that keep you from giving X10 a try. I've been using X10 extensively in my house for more than 2 years, and I have had very good results since I installed a signal bridge.
As you think about all the things you can automate around the house, plan for fail-safe operation. Think about what could go wrong and what effect it would have. For example, let's say you wanted to automatically turn on a coffee pot every weekday morning at 8:00 a.m. and turn it off at 10:00 a.m. What happens if you forget to put water in the coffeepot and it catches on fire? What if noise on the power line causes an appliance module to switch on in the middle of the night? Or what if an appliance module fails to turn off because your PC crashes and doesn't send the "off" command? Think through these situations and make sure you're comfortable with what happens when the system fails.
And don't forget the safety of all the equipment you've installed. Power surges or lightning strikes can wipe out thousands of dollars worth of electronic equipment in an automated home. Consider having an electrician install a whole-house surge protector in the breaker box. This approach provides protection for any permanently wired electronic equipment. You might also want to obtain a UPS for your PC; smaller models that provide 10 or 20 minutes of backup power cost less than $100.
One thing is certain. After you start automating your home, you're never finished. You can always find something else to automate, tweak, or upgrade. That's what makes home automation so much fun!