What it is, and where it sits in a line
The Square D Co. XU9N18PP341WD is a polarized retroreflective photoelectric sensor in the Telemecanique XU9 series, packaged in an 18 mm threaded stainless steel barrel with a 90 deg side sensing position and a 4-pin micro connector — the polarized optics suppress the specular bounce off shiny conveyor parts or shrink-wrapped trays, which is the whole point of paying for a polarized head over a plain reflex sensor on a packaging or bottling line. It runs on 12 to 24 VDC, switches up to 100 MILLIAMPERE on a 3-wire PNP NO/NC output, and answers in 1 MILLISECOND (ON/OFF) at an operating frequency of 500 HZ with a yellow LED flagging output state — fast enough for parts counting on a small conveyor, slow enough that you do not pay for a fiber-optic head you do not need.
Ratings that actually decide the fit
The 2 M sensing distance with a standard retroreflector is the working envelope a layout drawing is sized to, so verify reflector part number alongside the sensor on the BOM — polarized retroreflectives reject corner-cube reflectors that are not polarization-matched and the range collapses. NEMA 4X/12 and IP67 enclosure ratings on a stainless body mean the sensor survives washdown and caustic CIP environments, which is the usual reason an XU9 with an SS barrel gets specified over the plastic-bodied equivalents in food, beverage and pharma lines. Operating temperature is rated -13 to 131 DEG F, so it covers cold-storage docks and most line-side cabinets; ambient above that band forces a derate or a different housing. Approvals listed are UL, CSA and CE, covering North American and European panel acceptance; RoHS and REACH documentation is not included in this spec bundle.
Loop and wiring notes for the integrator
Three wires on a 4-pin micro connector with a PNP NO/NC output source current to the PLC input from a 12 to 24 VDC supply; confirm the cordset pinout against the sensor diagram before commissioning. Light/dark operating mode is selectable, so the same SKU can be wired to energize on beam-present (dark-on, typical for object-detected logic) or beam-broken (light-on, typical for missing-cap detection), and the yellow LED tracks the output state for a fast eyeball check at the machine.
Lifecycle and sourcing posture
The listed UPC is 78590160477 and the 12-digit UPC is 389110853837, which the receiving dock uses for incoming inspection against the PO line.