Omron E3T-ST21 5M Through-beam Photoelectric Sensor
Omron E3T-ST21 5M is an ultracompact through-beam photoelectric sensor designed for sensing targets across a 300 mm working distance. A red LED creates the optical path between the emitter and receiver, and interruption of that beam produces the switching condition processed by the built-in amplifier. The NPN output supports compatible industrial control inputs, while Light-ON operation defines the specified switching logic. Operating voltage is 12 to 24 VDC, and the model includes a 5 m pre-wired cable for extended connection length. Total current consumption is 30 mA maximum, with 10 mA maximum for the emitter and 20 mA maximum for the receiver. Within the E3T Series, the E3T-ST21 5M provides the long-cable NPN option. Similar 300 mm through-beam sensors can be reviewed across Omron Sensor Products.
| Brand | Omron |
| Product | Photoelectric Sensors |
| Model Number | E3T-ST21 5M |
Omron E3T-ST21 5M 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 5m |
| 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-ST21 5M Photoelectric Sensor uses through-beam sensing over a 300 mm distance with a red LED optical source and NPN output. The beam travels between the emitter and receiver, and interruption by a target produces the switching condition processed by the built-in amplifier. Light-ON operation provides the specified output logic, while response time is 1 ms maximum. The sensor operates from a 12 to 24 VDC supply and includes a 5 m pre-wired cable. Current consumption is specified at 30 mA maximum, with the emitter drawing up to 10 mA and the receiver up to 20 mA. Its square ultracompact format supports mounting where available sensor space is restricted.
For an Omron ultracompact through-beam sensor requiring a longer pre-wired connection, the applicable model is the E3T-ST21. PBT and denatured polyarylate are listed as housing materials, while the supplied specification gives IP67 protection. The 300 mm sensing distance, NPN output, and Light-ON switching configuration suit short-range machine sensing where a separate emitter and receiver are used. Search terms such as Omron NPN through-beam sensor and Omron 5 m cable photoelectric sensor also match this configuration. For the M3-mounting version with the same 5 m cable, NPN output, Light-ON operation, and 300 mm range, see the E3T-ST21M 5M. The longer cable provides additional routing distance between the sensor position and associated control equipment.
