## Overview: OMRON E3Z-R81 The **E3Z-R81** is a high-performance, compact photoelectric sensor developed by OMRON. It belongs to the E3Z series, which is industry-standard for general-purpose sensing. The "R" designation indicates it is a **Retro-reflective** model, meaning it requires a reflector to operate. --- ### Technical Specifications | Feature | Specification | | :--- | :--- | | **Sensing Method** | Retro-reflective with MSR (Mirror Surface Rejection) | | **Sensing Distance** | 100 mm to 4 m (with E39-R1S reflector) | | **Output Type** | PNP open collector | | **Operation Mode** | Light-ON / Dark-ON (Switch selectable) | | **Power Supply Voltage** | 12 to 24 VDC ±10% | | **Current Consumption** | 30 mA max. | | **Response Time** | 1 ms max. | | **Light Source** | Red LED (660 nm) | | **Connection Method** | Pre-wired (2m cable) | | **Degree of Protection** | IP67 (Waterproof) | --- ### Key Electronic Components & Features #### 1. MSR (Mirror Surface Rejection) Function The E3Z-R81 includes built-in polarizing filters. This is a critical electronic feature that allows the sensor to detect shiny or mirror-like objects. It only receives the light that has been depolarized by the reflector, ignoring the direct reflection from the object itself. #### 2. PNP Open Collector Output The electronic output stage uses a PNP transistor. * **Active State:** When triggered, the output pin connects to the positive supply voltage (Vcc). * **Load Capacity:** It can typically handle up to 100 mA at 26.4 VDC. * **Protection:** Includes short-circuit protection and reverse polarity protection. #### 3. Operation Mode Selector There is a physical switch (potentiometer-style) on the body that allows the user to toggle between: * **Light-ON:** Output is ON when light returns from the reflector (no object present). * **Dark-ON:** Output is ON when the beam is broken (object is present). --- ### Wiring Diagram (Electronic Interface) The following represents the standard wiring for the PNP output model: | Wire Color | Function | Connection | | :--- | :--- | :--- | | **Brown** | Vcc | +12 to 24 VDC | | **Blue** | 0V | Ground (GND) | | **Black** | Output | Connect to Load / PLC Input (PNP) | ```mermaid graph LR A[Brown: +VDC] --- Sensor((E3Z-R81)) B[Blue: 0V] --- Sensor Sensor --- C[Black: Output] C --- D[Load/PLC] D --- B ``` --- ### Indicator LEDs The sensor housing features two electronic visual indicators: 1. **Operation Indicator (Orange):** Lights up when the output is ON. 2. **Stability Indicator (Green):** Lights up when the received light intensity has enough margin (stable sensing) or is sufficiently blocked.