The **PM-R64** is a U-shaped (slot) micro photoelectric sensor manufactured by Panasonic (formerly SUNX). It is widely used in industrial automation for sensing the presence of objects, motor speed control (tachometry), and limit switching. --- ### ## 1. Technical Specifications Table The following table outlines the primary electronic and physical characteristics of the PM-R64: | Parameter | Specification | | :--- | :--- | | **Sensing Distance** | 5 mm (Fixed) | | **Supply Voltage** | 5 to 24 V DC ±10% | | **Current Consumption** | 15 mA or less | | **Output Type** | NPN Open-Collector Transistor | | **Output Operation** | Dual Output (Light-ON / Dark-ON) | | **Maximum Load Current** | 50 mA | | **Response Time** | 20 µs or less (under light received condition) | | **Peak Emission Wavelength** | Infrared LED (880 nm) | --- ### ## 2. Key Electronic Components The PM-R64 functions through an integrated circuit design that combines optical and electronic elements: #### **A. Infrared Emitter & Detector** Inside the "U" shaped housing, there is an **Infrared LED** on one side and a **Phototransistor** on the other. * **The Beam:** The LED emits a constant beam of infrared light across the 5mm gap. * **The Trigger:** When an object (like a gear tooth or a metal plate) enters the slot, it breaks the beam, changing the state of the phototransistor. #### **B. The NPN Open-Collector Output** The sensor utilizes an NPN transistor as a switch. * **Light-ON (L):** The output is active when the sensor receives light (no object in the slot). * **Dark-ON (D):** The output is active when the beam is interrupted (object present in the slot). * *Note:* Having both outputs allows for flexibility in logic wiring without needing external inverters. #### **C. Protection Circuitry** The internal electronics include: * **Reverse Polarity Protection:** Prevents damage if the power wires are swapped. * **Short-circuit Protection:** Protects the transistor from burning out if the load is shorted. --- ### ## 3. Wiring Configuration The PM-R64 typically uses a 4-pin connector or a 4-wire cable. The standard color coding/pinout is as follows: | Pin/Wire Color | Function | Description | | :--- | :--- | :--- | | **Brown** | +V | Positive Power Supply (5-24V DC) | | **Blue** | 0V | Ground / Common | | **Black** | Output 1 | Light-ON Output | | **White** | Output 2 | Dark-ON Output | --- ### ## 4. Application Logic Because of its high-speed response (20 microseconds), the PM-R64 is electronically ideal for: 1. **High-speed counting:** Counting pulses from a rotating slotted disk. 2. **Precise Positioning:** Detecting the home position of a CNC axis. 3. **Paper Detection:** Commonly found in high-end printers and copiers to track paper paths.