May 2004 - page 3
 Closed architecture systems typically do not provide their software to the end user. It is reserved for the installer to program and troubleshoot the installation. Some do offer very limited access to the system via software programs, but most do not, for the simple reason that if you do not know what you are doing, it would be very easy to crash your entire whole house audio/video distribution system. Trust me – if your telephone, security, HVAC and other important devices are tied into your whole-house system, you don’t want to be tinkering with the hub with reckless abandon. In a system of this nature, your various A/V devices connect to the hub – sometimes one box, but often several – and your installer jacks into the hub to program it to operate the devices connected to it. If you’re lucky, you will own at least a few devices that feature bi-directional RS-232 communication. This is a simple connection between the device to be controlled and the hub (looks like an oversized phone jack) using CAT5 cable. If you’re even luckier, the hub will automatically recognize the device connected to it and minimal programming is required. Unfortunately, this is not often the case. Many RS-232 jacks are not bi-directional (meaning they can only accept commands, not give commands or status information) or the jack is utilized for the sole purpose of “talking” to the device’s siblings (devices from the same manufacturer). Devices that usually feature bi-directional RS-232 communication are lighting control and security. This is needed so the lighting and security systems can communicate status information to the hub, which relays that information to the homeowner on the connected LCD touch screens. A/V devices, however, do not necessarily need to communicate such information and, therefore, often do not feature RS-232 communication. This leaves the installer no choice but to communicate with the “dumb” device via IR commands. The installer builds an interface that typically mimics that device’s remote control, and one-by-one teaches the hub each IR command. This type of programming expense, along with the physical installation, can often match or exceed the price of the A/V distribution equipment itself.
Even more confused now? I hope not, but it is clear to see this stuff ain’t cut and dried. This just about covers Part One of this How-To adventure. In Part Two I'll discuss what type of system works best depending on the size of your house and your individual desires. Stay tuned...
Joe Hageman is vice president of Caster Communications, a consumer electronics-based Public Relations firm. He was previously an equipment editor for Home Theater magazine and has written for E-Gear, Sound & Vision and Home Automation.
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