The **Omron E3S-R31** is a high-performance photoelectric sensor specifically designed for the detection of transparent objects (like glass or PET bottles). It operates on a retro-reflective principle with a built-in polarizing filter. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Sensing Method** | Retro-reflective with MSR (Mirror Surface Rejection) | | **Sensing Distance** | 100 mm to 1 m (with E39-R1 reflector) | | **Light Source** | Infrared LED (880 nm) | | **Supply Voltage** | 10 to 30 VDC (including 10% ripple) | | **Current Consumption** | 40 mA max | | **Control Output** | NPN / PNP selectable (depending on specific sub-model wiring) | | **Response Time** | 1 ms Max. | --- ### 2. Internal Electronic Components & Logic The E3S-R31 contains several critical electronic stages that allow it to differentiate between clear glass and empty space: #### A. Optical System (MSR Function) The sensor uses a **polarizing filter**. The emitter sends out polarized light. When this light hits a corner-cube reflector, its polarization is rotated 90 degrees and returned to the receiver. If a transparent object passes through, it slightly attenuates the light, which the internal circuitry detects. #### B. Output Circuitry The sensor typically features an open-collector output. Depending on the wiring configuration, it can handle loads up to 100mA. * **Light-ON / Dark-ON:** Selectable via a switch on the sensor body. * **Protection:** Includes reverse polarity protection and output short-circuit protection. #### C. Sensitivity Adjustment It features a **2-turn trimmer (potentiometer)**. This allows the user to fine-tune the threshold level, which is necessary because transparent objects reflect and absorb very little light compared to opaque objects. --- ### 3. Wiring Diagram Representation The following block represents the standard 3-wire DC connection for this sensor type: ```mermaid graph LR A[Brown: +Vcc 10-30V] --- B(E3S-R31 Sensor) C[Blue: 0V / GND] --- B D[Black: Control Output] --- B ``` ### 4. Application Considerations * **Stability Indicator:** A green LED indicates when the light received is within the stable operating range (not just at the threshold). * **Operation Indicator:** An orange LED indicates the status of the output. * **Environmental Sealing:** Rated at **IP67**, making the internal electronics resistant to water and dust. ---