What it is and what it does
The E3T-SL21 5M is a subminiature convergent-reflective photoelectric sensor with a built-in amplifier. It delivers a 30 mm sensing point using a red LED, switching NPN output in Light-ON mode. The body is compact rectangular plastic, pre-wired with a 5 m cable, and runs on 12 to 24 VDC. Convergent-reflective means the emitter and receiver are in one housing, focused at a fixed distance—so it ignores objects beyond that focal point, making it a clean choice for presence detection in tight spaces where background rejection matters. Type is listed as miniature, and the product lifecycle status is active.
Integration notes
The compact body (about 25 × 10 × 7 mm) fits where space is at a premium. The 5 m cable is fixed, so pre-plan your conduit or cable carrier route—no connector to swap later. Convergent-reflective range is measured from the lens face: 30 mm to the focal point. Account for target reflectivity: a polished white surface will give better margin than a dark matte surface; test with actual product before locking the bracket position. Supply voltage is 12–24 VDC, up to 50 mA load current. Light-ON means output transistor turns on when the received light is strong enough—verify that matches your PLC input logic.