# How to set up a retroreflective photoelectric sensor to detect an object on a conveyor belt (OMRON E3JK-R4M2)

**URL:** <https://www.robotexchange.io/t/how-to-set-up-a-retroreflective-photoelectric-sensor-to-detect-an-object-on-a-conveyor-belt-omron-e3jk-r4m2/5000>\
**Category:** 💡 How-to\
**Tags:** conveyor-belt\
**Created:** [November 4, 2026, 9:42am UTC](https://www.robotexchange.io/t/how-to-set-up-a-retroreflective-photoelectric-sensor-to-detect-an-object-on-a-conveyor-belt-omron-e3jk-r4m2/5000 "2026-11-04T09:42:05Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Niels\_Geerlings](https://www.robotexchange.io/letter_avatar_proxy/v4/letter/n/d2c977/32.png) [@Niels\_Geerlings](https://www.robotexchange.io/u/Niels_Geerlings)\
**Post date:** [November 4, 2026, 9:42am UTC](https://www.robotexchange.io/t/how-to-set-up-a-retroreflective-photoelectric-sensor-to-detect-an-object-on-a-conveyor-belt-omron-e3jk-r4m2/5000/1 "2026-11-04T09:42:05Z")

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**How to set up a retroreflective photoelectric sensor to detect an object on a conveyor belt (OMRON E3JK-R4M2)**

**How does the photoelectric sensor work?**  
A retroreflective photoelectric sensor detects an object when the object interrupts a light beam between the sensor and a reflector. The sensor and reflector are mounted on opposite sides of the conveyor belt. Under normal conditions, the reflector sends the emitted light back to the sensor. When an object passes through the beam, the reflected light is interrupted and the sensor changes its output state.

**How to wire the sensor**

| Color | Symbol | Function |
| --- | --- | --- |
| Brown (BN) | + | 12–24 V DC |
| Blue (BU) | − | 0 V |
| White (WH) | Tc | Common relay contact |
| Black (BK) | Ta | Normally open (NO) |
| Grey (GY) | Tb | Normally closed (NC) |

**Sensor position and stopping accuracy**  
Place the sensor as close as possible to the location where the object must stop. After the sensor detects an object, the conveyor may continue moving for a short distance before it stops. The closer the sensor is to the stopping position, the smaller this displacement will be.

The detection distance can be adjusted using the SENS potentiometer on the E3JK-R4M2. Turn the potentiometer gradually while testing the conveyor until the sensor detects the object reliably at the desired distance. After adjustment, verify that the sensor does not detect the conveyor belt or nearby objects by mistake.

 ![image](https://www.robotexchange.io/uploads/default/original/2X/b/b9439f38e7d7c7c23f117d677140b43bb4994c0f.jpeg)  
 ![image](https://www.robotexchange.io/uploads/default/original/2X/7/7032bd06cabc74f27e9b0b44b6173e72b2cc3143.jpeg)