The three major elements which are useful in making the home automated excluding the small devices are:
1. Hardware controllers or software controllers
2. Sensors
3. Actuators
Hardware Controllers or Software Controllers: The controller is a piece of software on a computer. Basically controller is a chip or extension card that interfaces with the device to control the action of the device according to the need of the customer. The controllers used in the home automation may be hardware or software depending on the necessity of the device. For example, when we are watching a television we can control the images in the room by using hand held remote. Coming to the software controllers, the code is written and is used for controlling the mechanism of the device. In general the controller carries out a number of functions like sending signals to on/off the lights, open and close contracts to operate voltage devices, issuing, displaying etc.
Sensors: In general sensors are used to sense the presence of an object. In the same way they are used to sense a physical quantity and convert that in to a signal which can be read by a machine or any observer.
Actuators: It is a mechanical device used for controlling or changing the position or even to clamp the position of a mechanism or system (i.e. to stop the motion of the home appliance)