Sensors are input devices which provide an output (signal) with respect to a specific physical quantity (input). In Industrial Automation, Sensors play a vital part to make the products intellectual and exceptionally automatic. Industrial Sensors are devices that are used to measure physical quantities such as temperature, pressure, humidity and flow rate. The following are the various types of Sensors used in Automation; Temperature Sensors, Pressure Sensors, Flow Sensors, Level Sensors, Proximity Sensors, Position Sensors, Force Sensors, Acceleration Sensors, Light Sensors, Sound Sensors, Torque Sensors and MEMS Sensors. Controllers is a comparative device that receives an input signal from a measured process variable, compares this value with that of a predetermined control point value (Set Point), and determines the appropriate amount of output signal required by the final control element to provide corrective action within a control loop.