Through-beam sensor set for long-range detection
The Omron E3FA-TN112M is a through-beam photoelectric sensor set with separate transmitter and receiver in M18 threaded plastic housings, prewired with a 2 m cable. It senses up to 20 m with a minimum opaque object of 7 mm diameter. Output is NPN, 100 mA maximum load, selectable light-on or dark-on switching. Through-beam gives you the longest range and most reliable detection in dusty or misty environments compared to retroreflective or diffuse sensors. The 0.5 msec response suits high-speed part counting or packaging lines. IP67 and IP69K ratings make it field-ready for washdown zones. Output reverse polarity protection, output short circuit protection, and power supply reverse polarity protection are built in. These protections reduce the risk of damage from wiring mistakes — a common cause of returns in the field.
How this compares to the PNP and connector siblings
The E3FA-TP112M is identical in every spec except output circuit: PNP instead of NPN. Same housing, cable length, sensing distance, response time, and ratings. If your PLC input expects a sourcing (PNP) signal, this NPN version will not interface without wiring changes. The E3FA-TN21 shares the same sensing performance and output type but uses a 4-pin M12 connector and a slightly taller housing (45 mm overall height). For panels already wired for connectors, the TN21 avoids a splice; for bare-wire terminations, the TN112M cable simplifies landing.