The **E3JK-R2M2** is a popular industrial-grade, long-distance photoelectric sensor manufactured by Omron (and various compatible brands). It belongs to the E3JK series, known for being a square-sized sensor with a built-in power supply, making it versatile for various electrical environments. --- ### 1. Core Technical Specifications The E3JK-R2M2 is a **Retro-reflective** sensor, meaning it requires a reflector to operate. | Feature | Specification | | :--- | :--- | | **Sensing Method** | Retro-reflective (with Polarizing Filter) | | **Sensing Distance** | Typically 2 to 5 meters (depending on reflector used) | | **Supply Voltage** | 24 to 240 VAC / 12 to 240 VDC (Multi-voltage) | | **Output Type** | Relay Output (SPDT - Single Pole Double Throw) | | **Control Output** | 3A at 250 VAC (Resistive Load) | | **Response Time** | 30 ms maximum | | **Light Source** | Red LED (Visible) | --- ### 2. Key Electronic Components & Functions #### A. Multi-Voltage Power Supply One of the most significant electronic features of the E3JK-R2M2 is its internal switching power supply. It can accept a wide range of voltages (both AC and DC), eliminating the need for a separate transformer or DC power brick in many industrial panels. #### B. Relay Output (Mechanical) Unlike NPN/PNP transistor sensors, the **R2M2** uses a mechanical relay. * **Terminals:** Usually consists of Common (COM), Normally Open (NO), and Normally Closed (NC). * **Advantage:** It can switch high-current AC loads directly. * **Disadvantage:** Slower switching speed and limited mechanical life compared to solid-state sensors. #### C. Polarizing Filter The "R" in the series often indicates a polarized retro-reflective system. The sensor contains optical filters that ensure it only detects light reflected back by the specific corner-cube reflector, preventing "false positives" from shiny objects (like a stainless steel can or a mirror) passing by. --- ### 3. Wiring Configuration The E3JK-R2M2 typically features a 5-wire cable: | Wire Color | Function | Description | | :--- | :--- | :--- | | **Brown** | Power (L/+) | Input Voltage (12-240V) | | **Blue** | Power (N/-) | Input Voltage (Neutral/Gnd) | | **White** | Relay Common | The "Com" terminal for the output | | **Black** | Normally Open | Connects to White when beam is interrupted | | **Gray** | Normally Closed | Disconnects from White when beam is interrupted | --- ### 4. Adjustments and Indicators * **Sensitivity Potentiometer:** Usually located on the back or top to adjust the threshold for detection. * **Operation Indicator:** A Red/Orange LED that lights up when the output is triggered. * **Stability Indicator:** A Green LED that indicates if the received light intensity is sufficient for stable operation.