The **WMS2-G3-R** is a high-performance, single-phase, bidirectional AC energy metering module. It is widely used in IoT energy monitoring, smart plugs, and industrial power management systems. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Input Voltage Range** | 100V - 240V AC | | **Maximum Current** | Up to 16A (typical) | | **Measurement Accuracy** | Class 1.0 (Active Energy) | | **Communication Protocol** | UART (Universal Asynchronous Receiver-Transmitter) | | **Frequency** | 50Hz / 60Hz | | **Parameters Measured** | Voltage, Current, Active Power, Power Factor, Energy | --- ### 2. Core Electronic Components & Architecture The WMS2-G3-R functions by converting analog signals from the AC line into digital data that a microcontroller can read. * **Shunt Resistor / Current Transformer:** Used to sample the current flowing through the load. Most compact modules use a high-precision shunt resistor. * **Voltage Divider Network:** A series of high-impedance resistors that step down the mains voltage to a safe, measurable level for the internal IC. * **Metering IC (SoC):** The "brain" of the module. It performs high-speed sampling of the voltage and current waveforms and calculates Root Mean Square (RMS) values. * **Optocoupler Isolation:** To protect the host microcontroller (like an ESP32 or Arduino), the UART communication lines are often isolated to prevent high-voltage surges from damaging the low-voltage electronics. * **LDO Regulator:** An internal Low-Dropout regulator that converts the input power into a stable 3.3V or 5V for the metering chip. --- ### 3. Pinout Description Typically, the module features a 4-pin or 6-pin interface for easy integration: 1. **VCC:** Power supply for the module (usually 3.3V or 5V). 2. **GND:** Ground reference. 3. **RX:** Receives data commands from the host. 4. **TX:** Transmits energy data to the host. 5. **CF1 / Pulse (Optional):** Some versions include a pulse output pin for energy calibration. --- ### 4. Application Logic The module operates in a **Master-Slave** configuration. The host sends a request frame via UART, and the WMS2-G3-R responds with a data packet containing the electrical parameters. ```python # Example Pseudo-code for reading data import serial # Initialize UART ser = serial.Serial('/dev/ttyS0', 9600, timeout=1) # Command to read RMS Voltage (specific to WMS2 protocol) read_voltage_cmd = b'\x01\x03\x00\x00\x00\x02\xC4\x0B' ser.write(read_voltage_cmd) response = ser.read(7) # Convert hex response to readable voltage voltage = int.from_bytes(response[3:5], byteorder='big') / 10.0 print(f"Current Voltage: {voltage}V") ``` ---