The **M2VT-12-R/K** is a high-performance **Signal Conditioner** (specifically a Potentiometer Transmitter) from the **M2-Series** manufactured by **M-System** (now MG CO., LTD.). Its primary function is to detect the position of a potentiometer (resistance) and convert it into a standard isolated DC signal. --- ### 1. Model Breakdown The suffix/model code defines the specific hardware configuration of the unit: | Code Segment | Description | Details | | :--- | :--- | :--- | | **M2VT** | Model Name | Potentiometer Transmitter | | **12** | Input Range | Total resistance 100 $\Omega$ to 10 k$\Omega$ | | **R** | Output Type | 4 – 20 mA DC (Load resistance 550 $\Omega$ max.) | | **K** | Power Supply | 85 – 132 V AC (47 – 66 Hz) | --- ### 2. Electronic Components & Internal Design This device is built using industrial-grade electronic architecture designed for reliability and noise immunity: * **Front-End Excitation Circuit:** * Provides a constant voltage to the potentiometer. * Designed to sense the "wiper" position without loading the circuit (high input impedance). * **Isolation Transformer:** * Provides **three-way isolation** (Input to Output to Power). * Typically rated for 2000V AC isolation to prevent ground loops and protect downstream PLC/DCS systems. * **Signal Processing (Analog/Digital Hybrid):** * Contains high-precision Op-Amps for zero and span adjustment. * Utilizes a reference voltage source to ensure temperature stability. * **Power Supply Module:** * An internal switching or linear regulator (depending on age/revision) that converts the 100V AC input into stable DC rails for internal logic. --- ### 3. Technical Specifications | Feature | Specification | | :--- | :--- | | **Input Signal** | Potentiometer (3-wire); Total resistance 100 $\Omega$ – 10 k$\Omega$ | | **Minimum Span** | 10% of total resistance | | **Output Signal** | 4 – 20 mA DC | | **Accuracy** | ±0.1% of span | | **Temp. Coefficient** | ±0.015% per °C (±0.008% per °F) | | **Response Time** | $\leq$ 0.5 seconds (0 – 90%) | | **Housing Material** | Flame-resistant resin (Black) | --- ### 4. Wiring and Terminal Layout The unit uses a **plug-in socket base** (usually the M2BS), allowing the electronic module to be replaced without disconnecting wires. 1. **Terminals 1, 2, 3:** Input from Potentiometer (CW, Wiper, CCW). 2. **Terminals 4, 5:** Output (+ / -). 3. **Terminals 6, 7:** Power Supply Input. --- ### 5. Adjustments The electronic faceplate typically features two multi-turn potentiometers (trimmers): * **ZERO:** Adjusts the 4mA point (typically ±5%). * **SPAN:** Adjusts the 20mA point (typically ±5%).