The Omron E3T-ST12 5M is a subminiature through-beam photoelectric sensor from the E3T series with a built-in amplifier. It runs on 12 to 24 VDC and delivers an NPN output configured for dark-ON operation. The fixed sensing distance is 1 meter, and the pre-wired cable extends 5 meters.
How it sits relative to the E3T-ST14
The E3T-ST14 is the closest functional sibling—same through-beam method, same 1 m sensing distance, same dark-ON logic. The critical difference: the ST12 is NPN, the ST14 is PNP. Cable length also differs—the ST14 comes with a 2 m cable. If your panel is wired for NPN, the ST12 fits. Moving to the ST14 means swapping output polarity and possibly extending the cable.
Mounting notes
Rectangular compact body in plastic. Through-beam alignment requires a clear line of sight between emitter and receiver. The 5 m cable gives flexibility for remote mounting; strip length and wire color follow standard Omron color code (brown +V, blue 0V, black output).