Abstract: A photoelectric sensor utilizing upper and lower numerical limits to control the output of the sensor. The sensor includes a transmitter and receiver and generates an internal signal whose magnitude corresponds to the magnitude of light received at the receiver. A controller activates the output driver on the basis of whether the magnitude of the internal signal lies between the upper and lower numerical limits. A user may set the limits numerically using a graphical user interface, and the magnitude of the internal signal may be measured numerically via an analog-to-digital converter. Successive readings may be averaged to improve accuracy.