The deTec4 Prime safety light curtain is an electro-sensitive protective device that complies with performance level “e” in accordance with EN ISO 13849 and SIL3 in accordance with IEC 61508. It has a 21-m scanning range and a 30-mm resolution. A built-in laser alignment aid provides a visible laser that helps save time when setting up or readjusting the light curtain. The curtain can be cascaded to protect multiple sides of a machine by connecting up to three pairs of light curtains using standard M12 connectors and can be configured via four different M12 system plugs without the need for a computer.