## Overview of the PM-L24-R The **PM-L24-R** is a subminiature, U-shaped (slot) photoelectric sensor manufactured by Panasonic (formerly Sunx). It is designed for high-precision object detection in automated machinery. --- ### 1. Key Technical Specifications The following table summarizes the primary electrical and physical characteristics of the sensor: | Feature | Specification | | :--- | :--- | | **Sensor Type** | U-shaped / Slot Photoelectric | | **Sensing Distance** | 5 mm (fixed) | | **Supply Voltage** | 5 to 24 V DC ±10% | | **Current Consumption** | 15 mA or less | | **Output Type** | NPN Open-Collector | | **Output Operation** | Dual (Light-ON / Dark-ON) | | **Response Time** | 20 µs or less (under light received) | | **Beam Source** | Infrared LED (940 nm) | --- ### 2. Electronic Component Breakdown The PM-L24-R consists of several internal stages that allow it to convert a physical obstruction into a digital signal: #### A. The Emitter (Transmitter) * **Infrared LED:** Located on one side of the "U" slot. It emits a narrow beam of infrared light (invisible to the human eye). * **Current Limiter:** Internal circuitry ensures the LED operates consistently across the 5-24V input range. #### B. The Receiver (Sensor) * **Phototransistor:** Located on the opposite side of the slot. It detects the infrared light from the emitter. * **Schmitt Trigger Circuit:** This internal component converts the analog signal from the phototransistor into a sharp, square-wave digital pulse, preventing "chatter" or false triggering. #### C. Output Logic * **NPN Open-Collector:** The sensor acts as a switch to the negative (GND) rail. When the sensor is triggered, it "sinks" current from the load to the ground. * **Flexible Output:** The unit usually provides two output wires (or a selectable wire) for Light-ON (active when beam is clear) and Dark-ON (active when beam is broken). --- ### 3. Connection Diagram The sensor typically uses a 4-wire configuration: ```text Brown (+) : 5 to 24V DC Blue (-) : 0V (GND) Black (OUT): Output 1 (e.g., Light-ON) White (OUT): Output 2 (e.g., Dark-ON) ``` ### 4. Application Considerations * **High Speed:** Because it has a response time of 20 microseconds, it can detect objects moving at high frequencies, such as gear teeth or motor encoders. * **R-Type Flexing Cable:** The "R" in the model name indicates a **flexible (robot) cable**, which is more resistant to repeated bending compared to standard cables, making it ideal for moving robotic arms. ---