Miniature Diffuse Sensor – Dark On, NPN
The Omron E3T-SL12 is a rectangular diffuse photoelectric sensor in the E3T series. It runs on 12-24 VDC, outputs an NPN signal, and switches Dark On—meaning the output is ON when the reflected light is absent (object detected). Sensing range is 5 mm to 15 mm at a 1 ms response time. IP67 and PBT body make it line-down tough for washdown or dusty spots.
Swap Alert – Dark On vs Light On Siblings
The E3T-SL12 is the only Dark On variant in the E3T diffuse series. The E3T-SL11 shares every other physical spec—same body, cable, IP67, 15 mm max—but switches Light On. If you're replacing an E3T-SL11 slot, dropping in an SL12 inverts the output logic without hardware change. No rewiring of the signal line, but the PLC or relay logic must accommodate a level reversal. The E3T-SL21 pushes max distance to 30 mm but is also Light On. The E3T-SL13 is PNP Light On. That means if your BOM called for PNP, the SL12's NPN won't pull your input high—check the card type.
Packed In – Protection and Power
The sensor carries output short-circuit protection, output reverse polarity protection, and power supply reverse polarity protection on board. That's three less external diodes and fuses to panel-build. Indicator light included, so you can walk the line and see the state without a scope.
Mech & Mounting at a Glance
11 mm deep, 7 mm wide, 25 mm tall. Right-angle sensing face (emitter and receiver in the same head). Prewired 2 m bare-wire cable—strip and land. Minimum detectable object is 0.15 mm diameter, so it catches small targets on a feed rail. Temperature floor -13 °F, ceiling 131 °F. CE marked.