What it is and where it fits
The Omron EE-SX871P is a through-beam photoelectric sensor in a compact slot-style housing. It uses a PNP open-collector output configured for Light-ON operation, meaning the output transistor switches on when the optical path between emitter and receiver is uninterrupted. The 5 mm slot gap is sized for edge detection on small parts, label registration marks, or flag interrupters in pick-and-place feeders and conveyor gates.
Mounting and environment
Chassis mount with M3 screws — two holes on a standard 25 mm pitch. The -25°C to 55°C operating range covers most indoor factory floors but not freezers or ovens. No IP rating is listed, so keep it inside a panel or protected from washdown.