### Overview of the E3JK-R2R3 The **E3JK-R2R3** is a high-performance, long-distance **Retro-reflective Photoelectric Sensor** manufactured by Omron. It is widely used in industrial automation for detecting objects by emitting a beam of light that bounces off a reflector and returns to the sensor. --- ### Technical Specifications | Feature | Specification | | :--- | :--- | | **Sensing Method** | Retro-reflective (requires a reflector) | | **Sensing Distance** | Up to 2.5 Meters (varies with reflector type) | | **Power Supply** | 12 to 240 VDC or 24 to 240 VAC (Universal Voltage) | | **Output Type** | Relay Output (SPDT) | | **Switching Capacity** | 3A at 250 VAC | | **Light Source** | Red LED (Visible) | | **Operation Mode** | Light-ON / Dark-ON (Selectable via switch) | | **Response Time** | 20 ms maximum | --- ### Key Electronic Components The E3JK-R2R3 is built with several integrated systems that allow it to function across various environments: #### 1. The Multi-Voltage Power Supply Unlike standard sensors that require a specific 12V or 24V DC input, this model contains an internal **switching regulator**. This allows the device to accept a wide range of voltages (12V-240V DC and 24V-240V VAC), making it highly versatile for different control panels. #### 2. Light Emitter and Receiver * **Emitter:** Uses a high-intensity red LED. * **Receiver:** Contains a photodiode tuned to the specific wavelength of the emitter to prevent interference from ambient sunlight or indoor lighting. #### 3. Relay Output (SPDT) The "R2R3" designation indicates a **Relay Output**. * It acts as a mechanical switch (Single Pole Double Throw). * **Pins:** It typically has a Common (COM), Normally Open (NO), and Normally Closed (NC) contact. * **Benefit:** It can directly switch AC loads (like a small motor or a large contactor) without needing an external transistor or PLC interface. --- ### Wiring Configuration The device typically utilizes a 5-wire cable system: | Wire Color | Function | Description | | :--- | :--- | :--- | | **Brown** | Power (L / +) | Connect to Live (AC) or Positive (DC) | | **Blue** | Power (N / -) | Connect to Neutral (AC) or Negative (DC) | | **White** | Relay Common (COM) | The shared terminal for the output switch | | **Black** | Normally Open (NO) | Closes when the object is detected (in Light-ON) | | **Gray** | Normally Closed (NC) | Opens when the object is detected (in Light-ON) | --- ### Installation Notes * **Alignment:** Since it is retro-reflective, the sensor and the reflector must be perfectly aligned. The red LED light is visible, which simplifies this process. * **Sensitivity Adjustment:** It usually features a potentiometer to adjust the sensing threshold, allowing it to detect transparent or semi-transparent objects. * **Environment:** Rated at IP64 or IP67, making it resistant to dust and water splashes.