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Centralized vs. Distributed Control

Real-Time vs. Programmed Control

Real-Time Control

Programmed Control

Automation System Control Types

Centralized vs. Distributed Control

The control and intelligence of a home automation system does NOT have to be totally centralized. On the contrary, even the most sophisticated home automation systems take advantage of "smart" equipment whenever practical. For example, a programmable VCR has built-in intelligence that a home automation system can access by sending it standardized commands via an infrared or serial interface.

Besides taking advantage of the preprogrammed intelligent functions of certain connected devices, some home automation systems might allow you to send additional commands to those devices to override or modify their preprogrammed functions. This type of capability expands the role of the home automation system to include what could be called "intelligence management."

Of course, there are many equipment items that have no intelligence of their own whatsoever. These devices, such as lamps, rely totally on the intelligence of the home automation system controller(s) for any automated functions.

Whenever practical, home automation systems should have at least one central controller, such as a personal computer or a dedicated system computer, where all control functions and programming features are available (with the exception of certain intelligent device functions that can only be programmed at the device itself). If this were the only controller in the system, the system could be described as totally centralized.

However, for user convenience you will usually want to distribute some of the control and intelligence. For example, you could install control keypads in several rooms. These keypads could be "smart" keypads that provide a subset of the central controller's capabilities, or they could be "dumb" keypads that function only as a user interface for the central controller. They could also be a combination of the two, with enough on-board intelligence to provide certain basic functions and still function as a user interface to the central controller for handling more complex tasks. They could also provide certain backup functions if the central controller broke down.

Another example of distributed control would be the use of an intelligent thermostat. Even if you could program the heating and air conditioning system from a central location, it would still be convenient for a user to be able to override the settings from the central controller and change thermostat temperature by simply pressing a button at the thermostat, rather than going through a sequence of keystrokes at a generic control keypad or having to walk into another room or start a computer program to make the change.

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Real-Time vs. Programmed Control

Control commands can be sent directly by the user (real-time control) or by a software or firmware program running on a controller (programmed control).

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Real-Time Control

In its simplest form, a home automation system allows you to execute real-time commands to control equipment in your home. For example, a simple home automation system might allow you to touch a few buttons on a wall-mounted panel to lower the lights, close the drapes, turn up the audio volume, and lock the front door.

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Programmed Control

The next step up in home automation systems allows you to program events to take place at scheduled times or in certain sequences. For example, you could program a system so that at a specific time the living room lights would dim, the blinds would close, and the television would switch on and tune in a specific program.

A control program can be a custom software program written especially for you, a pre-written program that you cannot change, or a pre-written program that allows you to change various operating parameters, allowing flexibility without requiring you to be a programmer.

The program may be run from a disk or CD, or it may be programmed into a chip in the controller. Some controllers may use both types.

To add even more power to home automation systems, some systems allow you to program events to take place when certain conditions are satisfied. To do this, you need system components that can provide feedback to the controller.

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