.

Many X10 devices have two dials that set the address of the device. One is labeled HOUSE CODE and has 16 positions (A through P). The other is labeled UNIT CODE and has 16 positions (1 through 16). This results in 256 possible addresses (A1 through P16). Some devices like the Mini-Controller only have a subset of these addresses (on the Mini-Controller only unit codes 1 through 4 are easily accessible with rocker buttons). Except for such device limitations, you are free to choose any of the 256 addresses for any simple system. Naturally, you must match the address of the controller with the controlled device. Since most X10 devices come set for A1 that is a good first choice unless you have close neighbors that also use X10 devices set to A1. In that case it is wise to choose a different house code. (That is why it is called a house code---different houses can use different codes and still have the 16 unit codes available for various devices within one house), Many of the newer controllers like the 6 button key chain remote do not have dials to set the address. Instead you must program the address by pressing a button a number of times corresponding to the code you wish to set. Needless to say, it is much more convenient to use addresses with low numbers and house codes near A. These devices come set to A1 (and reset to A1 when the battery is changed) so it is convenient to reserve the house code A for such devices.

Sorry, it isn't really that easy

(if you plan to have many devices in your system)

If all you want to do is control a reading light from your easy chair, you don't have worry about these additional considerations but if you are planning a whole house system with dozens of devices, you should do some careful planning. For starters---try to develop your system with only one house code. It will simplify your decisions and permit all your controllers to operate devices all over the house. While 16 available addresses might seem like more than enough, you will find that they get used all too fast. If you must use more than one house code, try to divide your tasks into actions that don't overlap or that you do not want to conflict. For example, if you assign house code A to inside lights you may want a different house code for outside lights or garage lights so that your kids (or you!) won't accidently turn on the outside lights from an inside controller. Remember that most controllers only allow sequential unit codes and one house code. If you use a Mini-Controller, for instance, you only have access to unit codes 1,2,3 and 4 (or unit codes 5,6,7 and 8) so you can't assign one lamp code A1 and another A7 and expect to conveniently operate them from the same Mini-Controller. The more expensive Maxi-Controller does address all 16 unit codes with individual buttons. Each controller has its own specifications, so be sure to read the fine print before you set up your system.

Watch for hidden control signals

(Eagle Eye Sensor Example)

There is a very popular and useful motion sensor called the Eagle Eye that generates X10 on and off signals when motion is detected in its field of vision. You can program it to send an ON signal to any X10 address when motion is detected. It then sends an OFF signal to the same address when motion ceases. Very useful. When you read the fine print, you find that it also sends ON and OFF signals to the unit code plus one corresponding to day and night (actually light and dark). If you don't want to use this feature you must be sure to avoid using that address (unit code plus one) for other devices because you can not disable these extra signals. This does tend to limit the useful address space of other controllers using the same code. Lets say you have 2 Eagle Eyes set to A1 and A3 and also want to use a Minii-Controller as a backup. Since A2 and A4 are now taken, you have used up the address space of the Mini-controller with these two items (assuming you don't want to have to move the selector on the Mini-controller every time you use it). And if you didn't take note of this extra feature, you could be very surprised when devices set to A2 or A4 turned on and off unexpectedly.

Special note on the Outdoor Floodlight Motion Detector

The X10 Motion Detector Floodlight requires special consideration because it can use up to 9 unit codes! It can be controlled by a base address that can be set to any value. You use this address to operate the lights from a remote location (i.e., you might want to turn on your garage floodlight from a bedroom if you hear a strange noise at night). The next four unit codes above the base address can be set to send X10 signals if motion is detected. You might want to turn on house lights with one of these addresses and operate an alarm with another. The next four unit codes are reserved for a day/night sensor. Fortunately, you can choose which of these eight codes you want to use and turn the others off. The problem comes if you have several floodlights and want to operate them with one controller.

Outdoor Floodlight Motion Detector Example

If you have four motion detector-floodlights (one each side of the house) you may want to control them separately. Thus you may want to assign consecutive unit codes to the base address the floodlights (i.e., B1, B2, B3, and B4 for example). Since these 4 addresses are taken, the only choice for the motion sensor alarm on the first unit is B5. The other units can be set to B5 if you want any of them to trigger the same alarm or to B6, B7 and B8 if you want each of them to trigger a different alarm. We have ignored the day/night sensor for this example since you may not want to use it. If you are not using it, be sure to switch off these addresses so you don't use even more address space.

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(C) Donald Scouten 2003