The **M2AVS-D112-R** is a specific model of an **Active Vacuum Sensor** (often categorized as a Pirani gauge) typically manufactured by companies like **MKS Instruments** or associated with the **M-Series** vacuum transducers. These parts are critical in semiconductor manufacturing, thin-film deposition, and laboratory vacuum systems. --- ### 1. Component Overview This device is a compact, thermal conductivity vacuum gauge. It translates the thermal conductivity of a gas into an electrical signal to measure pressure. | Specification | Details | | :--- | :--- | | **Sensor Type** | Pirani (Thermal Conductivity) | | **Measurement Range** | Typically $1.0 \times 10^{-4}$ to $1,000$ Torr | | **Output Signal** | Analog (0-10 VDC or similar nonlinear curve) | | **Connector Type** | D-Sub 9-pin (indicated by the "D" in the suffix) | | **Fitting/Flange** | 1/8" NPT or NW16 (depending on sub-variant) | --- ### 2. Electronic Architecture The internal electronics of the M2AVS-D112-R are designed to maintain a constant temperature in a fine filament. * **The Wheatstone Bridge:** The core circuit is a bridge where one arm is a heated filament exposed to the vacuum. As pressure changes, the gas density changes, carrying away more or less heat. * **Feedback Loop:** The electronics automatically adjust the voltage to keep the filament at a constant temperature. This "Error Voltage" is what is scaled and sent to the output pin. * **Signal Conditioning:** Includes internal temperature compensation to ensure that ambient room temperature does not drift the pressure readings. --- ### 3. Pinout Configuration (Standard D-Sub 9) While you should always consult the specific manual for your revision, the standard 9-pin D-sub configuration for these active sensors is typically: | Pin | Function | Description | | :--- | :--- | :--- | | **1** | Relay 1 NO | Setpoint 1 Normally Open | | **2** | Relay 1 Common | Setpoint 1 Common | | **3** | Power Input | +12 to +24 VDC | | **4** | Power Ground | Return for Power | | **5** | Analog Output | Pressure signal (0-10V) | | **6** | Signal Common | Ground reference for Analog Output | | **7** | Relay 2 NO | Setpoint 2 Normally Open | | **8** | Relay 2 Common | Setpoint 2 Common | | **9** | Status/Chassis | Shield or Device Status | --- ### 4. Critical Usage Notes * **Orientation:** It is electronically best practice to mount the sensor with the flange facing down to prevent particulate or oil contamination from falling onto the delicate filament. * **Calibration:** The "R" in the suffix often denotes a specific calibration or RoHS compliance standard. Because it is a thermal gauge, the output is "Nitrogen equivalent." If you are measuring Argon or Helium, you must apply a gas correction factor. ---