A proximity sensor is a transducer that detects objects or signals that are close to the sensor element. Inductive proximity sensors are designed to work generating a magnetic field and detecting the leakage current of the field generated when introduced into it the objects of ferrous and non-ferrous detection. Photoelectric sensors (photocells) are those who respond to changio in the intensity of light, allowing the activation or deactivation of a signal depending on the values received from that light.