Through-beam sensing at 39.37 mm — what it means for the line
The Omron E3T-ST11 is a through-beam photoelectric sensor from the E3T series, delivering a sensing distance of 39.37 mm with a red 650 nm LED source. The NPN open-collector output is configured Light-ON, meaning the output transistor turns on when the beam is uninterrupted — the normal state for part-present detection on a conveyor or pick-and-place cell. Response time is 1 ms, fast enough for most packaging and assembly lines running at moderate speeds. Rated IP67 and operating from -25°C to 55°C, this sensor handles washdown environments and outdoor cabinets without an extra enclosure. The 12 V supply and cable connection keep wiring straightforward — just confirm your PLC input card accepts NPN sourcing before committing the BOM.
How it compares to the E3T-FT11 — same footprint, different reach
The closest peer in the E3T series is the E3T-FT11, which shares the same NPN Light-ON output, IP67 rating, 1 ms response, and 12 V supply. The deciding difference is sensing distance: the E3T-ST11 reaches 39.37 mm, double the 19.685 mm of the E3T-FT11. If your existing panel was wired for the E3T-FT11, the E3T-ST11 drops in without rewiring — same output logic, same connector, same mounting footprint — but you gain extra alignment tolerance on the emitter-receiver axis.