The **E3JK-R2S3** is a long-distance photoelectric sensor manufactured by Omron (and various compatible brands). It belongs to the E3JK series, which is known for its built-in power supply and high-power sensing capabilities. --- ### 1. Technical Specifications The E3JK-R2S3 is a **Retro-reflective** sensor, meaning it emits light toward a reflector and detects an object when the light beam is interrupted. | Feature | Specification | | :--- | :--- | | **Sensing Method** | Retro-reflective | | **Sensing Distance** | Up to 2.5 meters (with E39-R1 reflector) | | **Supply Voltage** | 12 to 240 VDC / 24 to 240 VAC | | **Output Type** | Relay Output (SPDT) | | **Switching Capacity** | 3A at 250 VAC | | **Response Time** | 20 ms maximum | | **Light Source** | Red LED (Visible) | | **Operation Mode** | Selectable: Light-ON / Dark-ON | --- ### 2. Key Electronic Components & Wiring The sensor is designed to interface with both industrial PLCs and simple high-voltage circuits. #### A. Internal Structure * **Emitter/Receiver:** Uses a high-intensity pulse-modulated Red LED. The modulation ensures the sensor is not affected by ambient room light. * **Relay Output:** Instead of a transistor (NPN/PNP), it uses a physical relay. This allows it to switch AC loads directly without an external controller. * **Voltage Regulator:** A built-in "Multi-voltage" circuit allows it to run on almost any common power source. #### B. Wiring Configuration (5-Wire System) The E3JK-R2S3 typically uses a 5-core cable: | Wire Color | Function | Description | | :--- | :--- | :--- | | **Brown** | Power (L/+) | 24-240V AC/DC | | **Blue** | Power (N/-) | 24-240V AC/DC | | **White** | Relay Common | The "Com" terminal of the relay | | **Black** | Relay N.O. | Normally Open contact | | **Gray** | Relay N.C. | Normally Closed contact | --- ### 3. Adjustments and Indicators * **Sensitivity Adjuster:** A potentiometer on the back allows the user to fine-tune the detection threshold. * **Operation Indicator:** An Orange LED lights up when the output is triggered. * **Stability Indicator:** A Green LED indicates if the received light intensity is sufficient for stable operation. --- ### 4. Common Applications 1. **Conveyor Belts:** Detecting boxes or packages to trigger a stop/start sequence. 2. **Gate/Garage Openers:** Detecting the presence of a vehicle to prevent the door from closing. 3. **Parking Systems:** Monitoring car slots or entry/exit points.