Sensor Overview
The Omron E3T-SR21 5M is a compact retroreflective sensor from the E3T series, providing a 200 mm adjustable sensing range with NPN Light-ON output. Red LED (650 nm) emitter, 1 ms response time, and IP67 rating make it suited for packaging, material handling, and automated assembly lines where space is tight.
Sensing distance adjustable 10–200 mm via potentiometer to match the reflector distance. NPN open collector, Light-ON logic: the output transistor switches on when the light from the reflector is received. Verify your PLC input is sinking (NPN compatible) and that the load current stays under the device's maximum (not listed, but standard for this class). 12–24 VDC supply; the panel 24 V bus can power the sensor. IP67 enclosure: withstands washdown, dust, and oil mist. Mount with cable entry downward to prevent water ingress.
Cross-Shop Note: E3S-AR86
The E3S-AR86 is a larger retroreflective sensor with a 2 m fixed range, PNP output (Dark-ON/Light-ON selectable), and a connector instead of a pigtail. If your BOM was cut for an E3S-AR86, dropping in this E3T-SR21 means rewiring for NPN and mounting a smaller bracket. For a clean swap, you need the E3S-AR86; this E3T is for new builds where short range and NPN logic match the controller.
Field Fit & Wiring
Cable pre-wired: strip and terminate to a terminal block. Brown (supply), blue (0V), black (NPN output). No shield needed. Operating temperature -25°C to 55°C: fine for most indoor factory environments. Avoid direct sunlight on the lens or placement near ovens.