Omron E3T-SL21 5M Ultracompact Photoelectric Sensor
Omron E3T-SL21 5M is an ultrathin limited-reflective photoelectric sensor designed for object sensing across a 5 to 30 mm range. Its red LED supplies the optical source, while the built-in amplifier processes light returned from the target. The NPN output communicates the switching state to compatible industrial control circuits, and Light-ON operation defines the specified output behavior. The sensor operates from 12 to 24 VDC, consumes up to 20 mA, and includes a 5 m pre-wired cable for additional wiring length. Within the E3T Series, the E3T-SL21 5M provides the extended-cable NPN option. Related short-distance reflective sensors can be reviewed across Omron Automation Products.

| Brand | Omron |
| Product | Photoelectric Sensors |
| Model Number | E3T-SL21 5M |
Omron E3T-SL21 5M Photoelectric Sensor - Technical Specifications
| Specification | Value |
|---|---|
| Sensing Method | Limited Reflective |
| Shape | Square type |
| Sensing Distance | 5 to 30 mm |
| Power Supply Voltage | 12 to 24 VDC |
| Output Configuration | NPN |
| Connection Method | Pre-wired cable length 5m |
| Current Consumption | 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 | 20g |
The Omron E3T-SL21 5M Photoelectric Sensor uses limited-reflective sensing across a 5 to 30 mm range in an ultrathin square body. Its red LED provides the optical source, while the built-in amplifier processes light returned from the target. The NPN output communicates the switching state to compatible industrial control circuitry, and Light-ON operation defines the specified behavior. The sensor operates from 12 to 24 VDC and consumes up to 20 mA. Operate or reset time is 1 ms max. A 5 m pre-wired cable provides additional wiring length between the sensing point and control equipment, while the compact format supports restricted mounting areas.
For an Omron short range reflective photoelectric sensor requiring NPN output and longer wiring, the corresponding model is the E3T-SL21 5M. Polybutylene terephthalate is specified for the housing and denatured polyarylate for the optical section. IP67 protection is stated, with approximate weight of 20 g. This specification also suits searches for an Omron 30 mm NPN sensor and Omron 5 m cable reflective sensor. The 1 ms response supports part presence, position confirmation, and close-range switching in compact automated equipment and repetitive machine sequences. For the shorter-cable Light-ON version with the same sensing range, see E3T-SL21 2M.


