The Siemens 3RG7420-0AA00 is a SIMATIC PXO310 K21R diffuse photoelectric sensor with energetic optics, sized 31x20x12 mm. It operates on DC 10-30 V, provides a PNP dark-on output rated 150 mA, and detects objects up to 500 mm. The 2 m PUR cable (3x0.14 mm²) and IP68 rating suit washdown or dusty environments. The M18 optics thread allows mounting in standard brackets or through-hole fittings.
The 500 mm sensing range is specified for the diffuse (energetic) mode; actual detection distance depends on target reflectivity. The PNP dark-on logic means the output switches high when the light beam is interrupted — confirm this matches your PLC input polarity before wiring. The 150 mA continuous output can drive a small relay or PLC input directly, but inductive loads need a free-wheeling diode across the load.