The E3T-SL11 is a miniature square photoelectric sensor from the E3T series, using diffuse-reflective sensing with a red LED. It switches NPN (Light On) at 12-24V DC and carries IP67 for washdown areas. Sensing range is 5 to 15 mm; response time is 1 ms, and the maximum load current is 50 mA.
How the key ratings translate to fit
The 5–15 mm sensing distance range gives you both the minimum detectable object (0.15 mm diameter) and the maximum working distance. In a diffuse sensor the emitter and receiver are in the same housing, so no separate reflector or receiver is needed — aim the face at the target and mount. NPN output (Light On) sinks up to 50 mA, enough to drive most PLC inputs directly. The 1 ms response time suits moderate-speed detection (conveyors, part presence). The body is PBT, IP67 rated, and operates from -13 °F to 131 °F. Prewired with 2 m of bare-wire cable — no connector to source separately. The right-angle face orientation means the sensing axis is perpendicular to the cable exit. Onboard protections (output reverse polarity, output short-circuit, supply reverse polarity) reduce the chance of damage from wiring errors in the field.
A buyer sourcing E3T-SL11 may see the E3T-SR21 2M as a possible alternative, but it is a retroreflective sensor — it requires a reflector opposite the emitter and operates at up to 200 mm. The SL11 is diffuse: no reflector needed, range 15 mm. Physical form also differs: the SL11 is rectangular (25 x 7 x 11 mm), while the SR21 2M is cylindrical (11 mm diameter, 24 mm length). They are not drop-in interchangeable; a panel designed for diffuse sensing would need a mechanical and wiring change to use the retroreflective unit.