Home Automation and Security Systems
HA friendly security systems are surprisingly few and far between. There are currently three mainstream options that I am aware of, plus one homebrew option.
The "creme de la creme" of home security systems in terms of versatility is Comfort Home Controls system. The system unit has both inputs and outputs, supports X-10, and Infra Red control and also acts as an answer phone - which allows the owner to interact with the system by phone when they are away from home. The downside is that it is a complex to configure, although the new Configurator software is a huge improvement over previous efforts.
However, that said, once configured, it is reliable day-in, day-out. Comfort can be interfaced to third party systems using a "UCM module" which provides a serial interface, the protocol for which is published. I have written a Homeseer plugin for Comfort which is quite mature now, and has been further enhanced by Paul Gordon. There is also xAP support for Comfort available.
Next up, in the HA friendly stakes, is the Australian system Genesis. This has a serial interface, and is far more reasonably priced than Comfort. There is currently no European distributor for Genesis, but they are willing to ship from Australia. I don't have first hand experience of the panel, but it has a good reputation. Unlike comfort, it also uses conventional keypads and LCD displays - so if the idea of having to listen to menus being read out leaves you cold, this could be a better choice than Comfort.
Finally, in the ready built stakes, there is the Visonic Powermax wireless system. This has limited X-10 capabilities, and the wireless design makes it ideal for temporary fitting (perhaps to a rented property). Unfortunately, wireless connectivity also brings with it a number of downsides: the sensors require batteries, which have to be replaced from time-to-time, and the range is limited - they are generally not suitable for use in large properties or old properties with a thick walls. Combine these shortcomings with very limited programming features, and the net result is very much a system which is very much a last resort for the home automator.
The more adventurous may also want to consider the home-brew route. For alarm systems that do not use end-of-line sensing resistors, or can have this feature disabled, it is straightforward to interface the sensor contacts - whether PIR, or reed-switch, in parallel to a PC.
I had success with this approach using the A1 alarm panel from Henry's. Conveniently, the panel supplies a 5V switching voltage to dry contacts, making computer interfacing trivial. I used the (now discontinued) PC digital interface board from Maplin Electronics. However the Phaedrus VIOM module would work just as well. Arming and disarming status is available via an output that was ordinarily intended to drive an LED. Sensing of alarm triggering had to be done on an implicit basis - a contact closure when the system was armed indicated a possible alarm. Unlike the Comfort and Genesis panels, this approach provides on basic occupancy detection/sensing and doesn't allow for remote control of the alarm status itself.
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