Omron E3T-ST21M 2M Photoelectric Sensor
Omron E3T-ST21M 2M is an ultracompact through-beam photoelectric sensor with an M3-mounting format and a 300 mm sensing distance. Its red LED establishes the optical path between the emitter and receiver, while the built-in amplifier processes the beam interruption produced by a target. The NPN output communicates the switching state to compatible control circuitry, and Light-ON operation provides the specified logic. The sensor operates from 12 to 24 VDC and includes a 2 m pre-wired cable. Current consumption is specified at 30 mA maximum, divided between 10 mA maximum for the emitter and 20 mA maximum for the receiver. Within the E3T Series, the E3T-ST21M 2M provides the M3 Light-ON configuration. Related compact NPN photoelectric sensors are available across Omron Industrial Sensors.
| Brand | Omron |
| Product | Photoelectric Sensors |
| Model Number | E3T-ST21M 2M |
Omron E3T-ST21M 2M Photoelectric Sensor - Technical Specifications
| Specification | Value |
|---|---|
| Sensing Method | Through-beam |
| Shape | Square type |
| Sensing Distance | 300mm |
| Power Supply Voltage | 12 to 24 VDC |
| Output Configuration | NPN |
| Connection Method | Pre-wired cable length 2m |
| Current Consumption | 30 mA max. (Emitter 10 mA max., Receiver 20 mA max.) |
| Light Source (Wavelength) | Red LED |
| Operation Mode | Light-ON |
| Response Time | 1 ms max. |
| Degree Of Protection | IP67 |
| Material | Polybutylene terephthalate |
| Material Lens | Denatured Polyarylate |
| Weight | 40g |
The Omron E3T-ST21M 2M Photoelectric Sensor uses through-beam sensing across a 300 mm distance in an ultracompact M3-mounting format. A red LED establishes the optical path between the emitter and receiver, while the built-in amplifier processes the beam interruption created by the target. Its NPN output communicates the switching state to compatible control circuitry, and Light-ON operation defines the specified output logic. The sensor operates from 12 to 24 VDC and includes a 2 m pre-wired cable. Maximum current consumption is 30 mA, with 10 mA maximum for the emitter and 20 mA maximum for the receiver. Response time is specified at 1 ms maximum, supporting quick changes in machine sensing conditions.
For an Omron M3 through-beam sensor requiring NPN output and Light-ON operation, the appropriate model is the E3T-ST21M. Its 300 mm sensing range supports short-distance target monitoring where mounting space is limited. The supplied specification lists IP67 protection along with PBT and denatured polyarylate materials. The configuration also matches searches for an Omron ultrathin photoelectric sensor and Omron M3 NPN sensor. Because the emitter and receiver operate as separate sensing elements, correct optical alignment is important for maintaining the beam path across the stated distance. For an otherwise similar M3 version using Dark-ON switching, see the E3T-ST22M 2M. Both models use the same 12 to 24 VDC supply range and 2 m pre-wired connection length.
