Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: TUESDAY, December 13, 1994                   TAG: 9412130049
SECTION: EXTRA                    PAGE: 6   EDITION: METRO 
SOURCE: DAVID BUTLER
DATELINE:                                 LENGTH: Medium

ANSWERING QUESTIONS YOU MIGHT HAVE ABOUT PLC

What in the world is PLC? Power line carrier is a low-cost communications technique that operates over household electrical wiring. When you push a button on a PLC controller, it transmits a coded signal over the power line which instantly becomes visible to PLC receiver modules throughout the house. This signal "carries" a command which causes the selected module to turn on, turn off, dim or brighten.

Is a PLC system difficult to set up? The best thing about PLC is that it's so easy to use. Plug in a controller and one or more modules, and you're in business! No special wiring. No hassle. It's a great way to control outdoor lights, appliances, electric blankets ... just about anything electrical in the home.

How much does it cost to get started? A wide assortment of PLC controllers is available - from bedside consoles and timers to sophisticated whole-house systems. Most people start out with a timer and three or four modules. The PLC timer (which doubles as an alarm clock) costs about $30. Receiver modules start at about $10 each. An extra push-button console costs $10.

Which modules should I buy first? The plug-in lamp module - designed to switch or dim incandescent lights - is the most common type of receiver. PLC light switches are available for ceiling lights and other permanently wired fixtures. The appliance module is also popular. Instead of a dimmer, it contains an electromechanical relay. An appliance module can switch any electrical load that plugs into a standard wall outlet.

What are the little dials on the face of each module? One dial sets the unit ID number (1-16). This ensures that only the intended module responds to a command. You can create logical groups by giving the same unit number to one or more modules, a feature that often comes in handy. The other dial sets the house code. The house code helps prevent your PLC controller from turning on a neighbor's house. If you have a neighbor who uses PLC, simply choose a different house code.

What other controllers do you recommend? Apart from the timer console, the most practical controller is the eight-channel hand-held remote - no home control system should be without one. I also recommend a telephone responder, especially if your schedule is varied. After a long day, you can call ahead to turn up the heat or turn on an entrance light. Some responders can be accessed from local extensions, effectively turning every touch-tone phone in your home into a remote control station!

Can I use my personal computer to control PLC modules? Not exactly. The current generation of PC-based controllers (six models at last count) uses the computer only as a terminal. Shareware and commercial software programs are available for the Macintosh, Apple II and Commodore as well as DOS- or Windows-based computers. You can create detailed schedules, one-button macros, conditional commands and much more. Once you load a program into the controller, it can be disconnected from your computer.

What if you want to control something other than a light or plug-in appliance? No problem. Next time I'll discuss the full gamut of PLC receiver modules. The latest special-purpose modules add exciting possibilities to PLC-based home control. Even old hands may discover something new!

To receive a comprehensive list of companies that manufacture PLC controllers, including telephone responders, PC-based controllers and software, please send $1.50 and a self-addressed envelope to David Butler F-438, Department TWN, 14713 Pleasant Hill Road, Charlotte, N.C. 28278-7927. The list includes toll-free phone numbers, a summary of each company's products, and a bibliography of related books and articles.