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Actuators and sensors, defined in the previous paragraphs, include analog and digital units such as: wall switches, wall dimmers, electrical outlets, plug-in modules, relays, temperature sensors, thermostats, etc. These devices contain one PLM-1 IC and can receive commands from one or more controllers. Bidirectional devices are fully networked and may transmit data. Sensors and actuators are to be considered as “wired” by PLC.
Some sensors and actuators might support certain control functions, but these devices are, generally, neither very intelligent nor sophisticated. In many situations therefore, a controller will drive them. One of the most elementary forms of control is manual control. A simple PLC keyboard-display, plugged into any electrical outlet, enables you to control lighting, various loads, (e.g., coffee pot, lamps), temperature (pool, thermostat settings, exterior, etc.), and several other devices from anywhere in the house. For example, before going to bed, you will push the "all lights off" button on the keyboard. A given house may contain any number of keyboard-display units that are simply plugged into electrical outlets.
This form of control is not "Home Automation" since it is not automated. It is only Remote Control, but is already a very convenient application for several users. Remote Control functions may be set with a hand-held IR (Infra-Red) remote control device that uses an IR to PLC interface. A touch-tone phone may also serve this purpose: imagine the convenience, for example, of calling the country house to raise the temperature before you arrive! Remote control can also be achieved via the Internet, using a standard Web browser. Communicate with your house and control and program all house functions!
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