Motion Sensors

Most sensors on the market are passive infrared sensors (PIRs) and exist in both indoor and outdoor varieties, with the latter being commonly used as security lights that are mounted in the same area as the sensor. PIRs, like the EagleEye Motion Sensor (MS14), send an "on" message to specific but user-selectable X10 modules whenever motion is detected. Most models can also be configured to send "on" and "off" messages at dusk and dawn, respectively. Although some devices can send the message to more than one device (the PR511 and PSH01 spring to mind, both of which contain built-in floodlights), most only communicate to a single device, requiring a computer in your X10 setup to relay this message to other devices if required. You'll discover how later!

Gateways and Other Exotic Devices

A gateway is any device that allows communication data to flow through it, despite each side of the conversation having different protocols. In most technologies, a gateway performs a two-way function, converting the protocols in either direction. In an X10 gateway, there is generally only one direction, that is, into X10.

The primary device in this category is the TM13U, the RF-to-X10 gateway that I've touched upon already. One of these devices, shown in Figure 1-12, allows a wireless RF remote control to place messages onto the power lines for an X10 device to process. It never does the reverse. This device will listen for all RF messages coming from the same house code as is set on its front dial and retransmit them (using the same house code) to the mains line (provided that the socket is switched on). If the dial is set to P, however, it will respond to RF signals for all house codes but retransmit them on the original house code. This device generally has a hardwired address of 1.

Figure 1-12. The TM13U, 122 x52 x33mm, or 224 x52 x22mm with aerial extended

To transmit over two or more phases, you will need a coupler. This will listen for X10 signals on one phase of the mains and replicate it on another. This can either occur in single unit (like the TF678) or require a separate device for each phase that needs to be coupled (an FD10, shown in Figure 1-13).

Both of these coupler devices are, in fact, known as filter/couplers, meaning that instead of duplicating the X10 messages, they can filter them out entirely, thereby preventing the messages from leaking into your neighbors' houses. And by extension, they can prevent your neighbors' X10 devices from controlling yours.

Figure 1-13. The FD10, an interesting filter/coupler module, looking very uninteresting

A bridge is a device that functions as a go-between for two different protocols. In this context, the protocols invariably exist to bridge home automation systems such as from X10 to C-Bus or from X10 to UPB PulseWorx. Such devices are useful for upgrading systems piecemeal or for controlling very specific devices that don't exist on your system and/or for which no suitable software drivers exist. However, the cost involved in both the bridging device and the original module would have to be very special to make it worth the money in most cases.

This, and many other exotic devices, are covered in Table 1-4.

Table 1-4. Miscellaneous X10 Controllers

Miscellaneous Device

Name

FD10

MS14

PR511

PSH01

TF678

TM13UAH

DIN Filter and coupler PIR-EagleEye Motion Sensor PIR with flood light Power horn siren Whole House filter RF-X10 Gateway

Computer Control

But far the most powerful and creative device available is a computer interface, such as the CM11, as shown in Figure 1-14. This is a transceiver that's able to pass messages from the power line to the computer and send messages back from the computer onto the power line. Unlike most X10 devices, the power socket on the CM11 is not controllable by X10 and instead is a simple through port. Consequently, if you want to control your computer with X10, you have two options.

■ Caution Be wary about putting the computer's power onto the normal house code, because you might accidentally switch it off when issuing an "all units off" message.

First, you could assign the computer an unused unit code and configure the computer to issue a shutdown command when it is seen on the power line. (I'll show you how shortly.) Second, you could use a separate appliance module and simply plug the computer into it. This is a workable although poor solution, since you're likely to have the machine plugged into an uninterruptible power supply unit (UPS).

Figure 1-14. The CM11EFL

In addition to being a controller, this device can also act as an event scheduler and message-relay system, even when not connected to a computer. Therefore, you can use the software (that is, the supplied Microsoft Windows version or a Linux equivalent, such as Heyu) to program the device and let it run stand-alone, since this programmed information now lives within its own EEPROM, which retains the data even if there is no power, allowing it to be moved from one place to another without reprogramming. (This also means it's possible to have a—slightly—automated house without a single computer!) However, you must keep a copy of the file and data that you uploaded to the CM11, since it is impossible to download it from the device.

■ Caution When unplugging the CM11U from either the mains or the computer, always remove the serial cable from the device first, because stray noise from the cable can affect the internal memory and its settings.

The event scheduler allows you to send any X10 messages at any time of the day, on any days of the week, between any dates of the year. On its own, the device doesn't have the ability to vary the times randomly, but it does have a dusk and dawn setting that works after you've given it details of your physical location as a longitude and latitude. You can find your longitude/latitude from an atlas or (if we're being serious for a moment) one of the many geo sites on the Web. Your IP address is often accurate enough for these calculations and is available from sites such as the following:

http://api.hostip.info/get_html.php?position=true http://whatismyipaddress.com

In CM11 parlance, the message-relay system is termed a macro. This allows an X10 message (such as "bedroom light on") to spawn additional custom messages to any, or all, of your other equipment. A typical macro might consist of "landing light to 50 percent," "bathroom light on," and so on. These messages can be separated in time, allowing a single "bathroom light on" message to become a short program such as this:

Bathroom light on Stairs light to 50% Wait 5 minutes Toilet light off Wait 2 minutes Stairs light off

So, in short, the CM11 can provide most of the functionality an automated house could want, albeit in a very static way. For your CM11 to dynamically process X10 messages, you'll need the computer on permanently and some software. Unfortunately, the software with which CM11 currently ships is for Microsoft Windows only. So instead, you can call on the community for software such as Heyu, which works as a replacement.

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