The **M2UDS-B2-R/CE** is a high-precision digital panel meter manufactured by **M-System** (now part of MG CO., LTD). It belongs to the M2UDS series, specifically designed to accept DC voltage or current inputs and provide a clear digital readout along with relay contact outputs for alarm or control purposes. --- ### 1. Technical Specifications Overview | Feature | Specification | | :--- | :--- | | **Model Type** | Digital Panel Meter (1/8 DIN size) | | **Power Input** | 100 – 240V AC (indicated by /CE marking) | | **Input Signal** | DC Current or Voltage (Universal/Configurable) | | **Output Type** | Relay Contact Output (High/Low Alarms) | | **Display** | 4-digit Red LED (Height: 14.2 mm) | | **Accuracy** | ±0.1% rdg ±1 digit | | **Sampling Rate** | Approx. 4 times per second | --- ### 2. Electronic Component Breakdown #### A. Input Section (Signal Conditioning) The device features a high-impedance input stage to prevent loading effects on the measured circuit. * **Voltage Input:** Typically ranges from ±10V DC to ±100mV. * **Current Input:** Uses an internal shunt resistor (typically 10Ω to 250Ω) to convert 4-20mA or other currents into measurable voltage. * **Isolation:** The input is galvanically isolated from the power supply and output terminals to protect the internal circuitry from ground loops and surges. #### B. Processing & A/D Conversion * **Analog-to-Digital Converter:** It uses a high-resolution A/D converter to translate the analog input into a digital value. * **Microprocessor:** An internal CPU handles scaling (turning a 4-20mA signal into a 0-100% display), zero/span adjustments, and alarm setpoint logic. #### C. Control & Output (The "R" Suffix) The **"R"** in the model code stands for **Relay Output**. * **Relays:** It contains two SPDT (Single Pole Double Throw) relays. * **Function:** These are used for "Hi" and "Lo" alarm trips. When the input exceeds or falls below a user-defined threshold, the electronic switch triggers the mechanical relay to open or close an external circuit. #### D. Power Supply Section (/CE Marking) * **Switching Power Supply:** The unit incorporates a high-efficiency AC/DC converter. * **Compliance:** The `/CE` indicates the electronic components meet European safety (LVD) and Electromagnetic Compatibility (EMC) standards, meaning it has internal filtering to reduce electronic noise interference. --- ### 3. Terminal Configuration (Simplified) | Terminal No. | Function | Description | | :--- | :--- | :--- | | **1 - 2** | Power Supply | 100-240V AC Input | | **3 - 5** | Relay 1 (Hi) | Common, Normally Open, Normally Closed | | **6 - 8** | Relay 2 (Lo) | Common, Normally Open, Normally Closed | | **9 - 10** | Signal Input | Positive (+) and Negative (-) DC Leads | --- ### 4. Key Application Use-Case This part is commonly used in industrial control panels to monitor **Level, Pressure, or Temperature** transmitters. If a tank level (represented by 4-20mA) gets too high, the electronic relay inside the M2UDS-B2-R/CE will click over, triggering a pump to stop or an alarm buzzer to sound.