The Omron E3S-CT66-L is a through-beam photoelectric sensor in a rectangular metal housing rated water and oil-resistant, intended for compact machine zones where cutting fluids or washdown are present. It emits an infrared LED and senses radially at a maximum 700 mm. The output is field-selectable NPN or PNP, and the operating mode toggles L-ON or D-ON, so a single SKU covers both sinking and sourcing architectures.
Supply voltage range is 10 to 30 VDC, typical for industrial DC sensor busses. The M12 4-pin pinout follows the standard photoelectric sensor wiring; confirm polarity on the selectable output terminals before powering.