Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, April 18, 1995 TAG: 9504180102
SECTION: EXTRA PAGE: 3 EDITION: METRO
SOURCE: DAVID BUTLER
DATELINE: LENGTH: Medium
A: A wide selection of products is available that can transform your PC into a dutiful servant. Properly equipped, your personal computer can dim the lights, maintain the temperature, watch out for intruders, operate your audio/video gear, and much more. Of course, you don't need a computer to do these things. But a little automation can make life easier - and you'll have lots of fun getting there!
In contrast to a professionally installed system, PC-based home control appeals to someone who prefers the hands-on approach. You can start small, adding new features as funds permit. The best part: The latest home-brew systems feature graphical software that almost anyone can learn to use.
The best strategy is to start with an inexpensive power line carrier (PLC) controller (about $50). Versions are available for DOS, Windows, Macintosh and Commodore. It can schedule as many as 256 lights and small appliances using plug-in receiver modules. A special relay module is available for switching low voltage loads such as sprinkler valves.
More powerful PLC controllers start at around $300. These go beyond basic schedules, incorporating macros and conditional logic statements. A macro is a series of commands that will execute at the touch of a button. For example, you could initiate a good-night or weekend-away routine by pressing a single key on a telephone keypad, tabletop control panel or hand-held remote.
Systems that support conditional logic (IF-THEN-ELSE) are referred to as programmable controllers. However, don't let the word ``programmable'' scare you. Developers go to great lengths to make their software as easy to master as, say, a word processing program. The graphical user interface creates the actual program statements, based on information that you provide.
Programmable controllers include, at a minimum, a small number of hard-wired inputs and outputs (direct I/O). These provide added flexibility for connecting security, environmental and other real-world sensors. Some models can be expanded to accommodate I/O intensive applications. Several companies recently introduced PLC controllers that comply with the new CEBus (Consumer Electronics Bus) standard.
You don't need to give up your computer to set up a home automation system. All PLC controllers (including some that support direct I/O) are designed to operate independently, leaving your computer free for spreadsheets, multimedia or whatever. When you need to modify a schedule, add a product, or simply view the status of your home, your PC becomes the controller's primary user interface.
On the other hand, you can save money by relegating an unused PC to the full-time responsibility of running your house. This approach allows you to choose less expensive I/O adapters and peripherals (those without an on-board processor). More importantly, you'll be able to incorporate applications that plug into a PC expansion slot.
Add-on boards are available that can answer the phone, take messages and respond to touch-tone commands. A speech processing board can give your system a voice (and personality) as well as recognize spoken commands. Some systems can even display menus on a television, giving you complete control from a hand-held remote.
To receive a comprehensive list of companies that manufacture PC-based home control systems, software and components, please send $1.50 and a self-addressed envelope to David Butler F-506, Department TWN, 14713 Pleasant Hill Road, Charlotte, NC 28278-7927. The list includes toll-free phone numbers and a summary of each company's products.
TECHTALK: Direct I/O can either be analog or digital. Analog inputs accept measurement sensors (e.g., temperature or humidity) while digital inputs can only detect switch closures. Digital outputs can be used to switch small electrical loads or to signal another device. Analog outputs have little use in the home.
butler shirttail
by CNB