The **W2AP-D24-R/UL** is a specific model of an industrial-grade **Dual-Channel Inductive Loop Detector**, typically used in parking systems, toll booths, and gate control applications. It is designed to detect the presence of vehicles by monitoring the change in inductance of a wire loop buried in the pavement. --- ### 1. Technical Specifications The "D24" in the model name indicates a **24V AC/DC** power requirement, which is standard for industrial PLC and gate controller environments. | Feature | Specification | | :--- | :--- | | **Power Supply** | 24V AC/DC (±10%) | | **Channels** | Dual Channel (Can monitor two separate loops) | | **Output Type** | Relay Output (Form C / SPDT) | | **Sensitivity** | Adjustable (usually via DIP switches) | | **Response Time** | ~100ms | | **Frequency Range** | 20 kHz to 170 kHz | | **Mounting** | 11-pin Circular Plug-in (DIN Rail compatible) | --- ### 2. Core Electronic Components The device consists of several critical internal subsystems: #### A. The Oscillator Circuit The heart of the device. It generates a high-frequency sine wave that passes through the external wire loop. When a metallic object (vehicle) moves over the loop, the **inductance decreases**, causing the oscillation frequency to **increase**. #### B. Microprocessor Control The internal logic chip monitors the frequency shifts. It distinguishes between actual vehicles and environmental "drift" (like temperature changes or humidity affecting the ground). #### C. Configuration Interface (DIP Switches) Located on the front or side, these allow the user to adjust: * **Sensitivity:** High sensitivity for motorcycles; lower for large trucks. * **Frequency:** Used to prevent "crosstalk" if two loops are placed close together. * **Presence/Pulse Mode:** Determines if the relay stays closed as long as the car is there, or just "blips" when the car arrives. #### D. Relay Isolation To protect the sensitive electronics from the high-voltage or high-current motors of a gate, the device uses **Electromechanical Relays**. These provide "dry contacts" for the controller. --- ### 3. Pinout Configuration (Standard 11-Pin) The W2AP series generally follows the industry-standard 11-pin circular base: | Pin Number | Function | | :--- | :--- | | 1 & 2 | Power Supply (24V) | | 3 | Relay 2 (Normally Open) | | 4 | Relay 2 (Common) | | 5 | Relay 1 (Normally Open) | | 6 | Relay 1 (Common) | | 7 | Loop 1 Input | | 8 | Loop 1 Input | | 9 | Loop 2 Input | | 10 | Loop 2 Input | | 11 | Relay 1 (Normally Closed) | --- ### 4. Safety & Compliance * **UL Listed:** The "/UL" suffix indicates it has been tested and certified by Underwriters Laboratories for safety standards in North America. * **LED Indicators:** Usually features LEDs for "Power," "Detect," and "Fault" (detects if the loop wire is broken or shorted).