What is Normal Sensor?

Basically a normal sensor is a device capable of sensing physical quantities like temperature, pressure, flow etc. and gives an output correlated to that quantity. And this output can either be an on/off signal, i.e., a switching signal, such as a proximity sensor, or it can be an analog representation of a continuously measured physical quantity, usually in the form of millivolts or some change in resistance value, such as thermocouples or pressure sensors. A common sensor by itself will not be sufficient to be able to use this measured value in an automation system. Instead, a transducer is introduced to enable converting these measured millivolts or resistance into a usable format such as 4 to 20 mA. Then you will need a computing capability like a PLC to use these measured values in some calculations and actions for automation processes.