The **M2D2-24-R/Q** is a high-performance **Dual-Channel Inductive Vehicle Loop Detector**, typically used in parking systems, gate control, and traffic management. This device identifies the presence of vehicles by detecting the change in inductance of a wire loop buried in the pavement. --- ### 1. Key Technical Specifications Below are the primary electronic characteristics of the unit: | Feature | Specification | | :--- | :--- | | **Input Voltage** | 24V AC/DC | | **Operating Current** | 100 mA (max) | | **Channels** | Dual (Controls two separate loops) | | **Output Type** | Relay (Form C - SPDT) | | **Sensitivity Levels** | 10 Selectable levels per channel | | **Frequency Range** | 20 kHz to 100 kHz (4 settings) | | **Operating Temperature** | -30°C to +70°C | --- ### 2. Core Electronic Components & Features #### A. The Oscillator Circuit The heart of the device is an LC (Inductor-Capacitor) oscillator. When a vehicle (metal mass) passes over the external loop, it acts as a shorted turn, decreasing the loop's inductance. The internal circuitry detects this frequency shift. #### B. Sensitivity & Boost (Q Feature) * **Sensitivity Selection:** Allows the detector to ignore small metal objects (like bicycles) or detect high-chassis vehicles (like trucks). * **Automatic Sensitivity Boost (ASB):** Increases sensitivity to maximum once a vehicle is detected, ensuring that the connection isn't lost while a high-clearance trailer is passing over the loop. #### C. Relay Configurations (R/Q Logic) The "R" and "Q" designations often refer to specific relay behaviors: * **Presence Mode:** The relay stays energized as long as the vehicle is over the loop. * **Pulse Mode:** The relay triggers for a short duration (approx. 150ms) either upon entry or exit from the loop. #### D. Environmental Compensation The electronics include **Automatic Drift Compensation**, which allows the unit to function reliably even as environmental factors (like ground moisture or temperature) change the baseline inductance of the loop over time. --- ### 3. Connection Pinout (Typical 11-Pin Plug) ```text Pin 1: Power Input (+) Pin 2: Power Input (-) Pin 3: Relay 2 (N.O.) Pin 4: Relay 2 (Common) Pin 5: Relay 1 (N.O.) Pin 6: Relay 1 (Common) Pin 7: Loop 1 Input Pin 8: Loop 1 Input Pin 9: Loop 2 Input Pin 10: Loop 2 Input Pin 11: Relay 1 (N.C.) / Fault Output ``` --- ### 4. Diagnostic Indicators The unit typically features LEDs to provide real-time electronic feedback: * **Green LED:** Power status and heartbeat. * **Red LED:** Detection status (solid when a vehicle is present, blinking to indicate a loop fault such as a short or open circuit).