The **KGS21-R** is an industrial-grade **Photoelectric Sensor**, specifically a through-beam or retro-reflective sensor (depending on the specific sub-model configuration) commonly used in elevators, automatic doors, and industrial automation for object detection. Below is a detailed breakdown of its electronic components and technical specifications. --- ## 1. Technical Specifications The following table outlines the core electrical characteristics of the KGS21-R: | Parameter | Specification | | :--- | :--- | | **Operating Voltage** | 12V - 24V DC / 24V - 240V AC (Multi-voltage) | | **Current Consumption** | $\leq$ 2W | | **Sensing Distance** | Up to 10 meters (Model dependent) | | **Output Type** | Relay Output (Contact: NO/NC) | | **Response Time** | $\leq$ 20ms | | **Light Source** | Infrared LED (940nm) | | **Protection Rating** | IP65 (Waterproof/Dustproof) | --- ## 2. Key Electronic Parts & Functionality ### A. Infrared Emitter & Receiver The device consists of two primary electronic stages: 1. **Emitter (TX):** Uses an **Infrared LED** to pulse light across a specific distance. Pulsing is used to differentiate the sensor's light from ambient light or sunlight. 2. **Receiver (RX):** Uses a **Phototransistor** or **Photodiode** paired with an optical lens to capture the incoming IR signal. ### B. Signal Processing Circuitry * **Oscillator:** Generates the frequency for the IR pulse. * **Amplifier & Filter:** The receiver includes an internal IC that amplifies the weak signal from the photodiode and filters out noise (interference from other light sources). * **Comparator:** A logic circuit that determines if the light beam is "Broken" or "Established" based on a predefined threshold. ### C. Output Mechanism (Relay) Unlike NPN/PNP transistors found in smaller sensors, the KGS21-R typically utilizes a **Mechanical Relay**. * **Dry Contacts:** It provides a COM (Common), NO (Normally Open), and NC (Normally Closed) interface. * **Isolation:** The relay provides galvanic isolation between the sensor’s power supply and the load it is controlling. --- ## 3. Wiring Diagram Representation The device usually follows a standard 5-wire color code: ```text [ Power Supply ] Brown (L / +) ----> AC 24-240V / DC 12-24V Blue (N / -) ----> AC 24-240V / DC 12-24V [ Relay Output ] White (COM) ----> Common Terminal Black (NC) ----> Normally Closed Gray (NO) ----> Normally Open ``` --- ## 4. Application Environments * **Elevator Doors:** Detecting passengers to prevent the door from closing. * **Parking Barriers:** Detecting the presence of a vehicle. * **Conveyor Belts:** Counting items or detecting jams.