DDM18SR ดิจิทัลวัตต์มิเตอร์ วัดพลังงานไฟฟ้า 1 เฟส MODBUS / RS485 https://www.ioxhop.com/p/1138

DDM18SR_ESP32_Read.ino

/* Dev by IOXhop.com */

#define DE_RE_PIN 4
#define MODE_SEND HIGH
#define MODE_RECV LOW

void setup() {
  pinMode(DE_RE_PIN, OUTPUT);
  digitalWrite(DE_RE_PIN, MODE_RECV);
  
  Serial.begin(115200);
  
  Serial2.begin(9600, SERIAL_8E1, 16, 17); // Rx, Tx
  Serial2.setTimeout(200);
}

uint16_t CRC16(uint8_t *buf, int len) {  
  uint16_t crc = 0xFFFF;
  for (uint16_t pos = 0; pos < len; pos++) {
    crc ^= (uint16_t)buf[pos];    // XOR byte into least sig. byte of crc
    for (int i = 8; i != 0; i--) {    // Loop over each bit
      if ((crc & 0x0001) != 0) {      // If the LSB is set
        crc >>= 1;                    // Shift right and XOR 0xA001
        crc ^= 0xA001;
      } else {                           // Else LSB is not set
        crc >>= 1;                    // Just shift right
      }
    }
  }

  return crc;
}

uint8_t readModbusRTU(uint8_t devAddr, uint8_t fnCode, uint16_t startAddr, uint8_t dataLen, uint8_t* buffRead) {
  uint8_t buff[8] = {
    devAddr,          // Devices Address
    fnCode,           // Function code
    startAddr >> 8,   // Start Address HIGH
    startAddr & 0xFF, // Start Address LOW
    0x00,             // Q HIGH
    dataLen,          // Q LOW
    0x00,             // CRC LOW
    0x00              // CRC HIGH
  };

  uint16_t crc = CRC16(&buff[0], 6);
  buff[6] = crc & 0xFF;
  buff[7] = (crc >> 8) & 0xFF;

  digitalWrite(DE_RE_PIN, MODE_SEND);
  Serial2.write(buff, sizeof(buff));
  Serial2.flush(); // wait MODE_SEND completed
  digitalWrite(DE_RE_PIN, MODE_RECV);

  char findStr[] = { devAddr, fnCode, 0 };
  if (Serial2.find(findStr)) {
    uint8_t n = Serial2.read();
    if (n != dataLen * 2) {
      Serial.println("Error data size");
      return 0;
    }

    Serial2.readBytes(buffRead, n);

    if (Serial2.available() < 2) delay(1);

    uint16_t crc16 = 0;
    crc16 |= Serial2.read();
    crc16 |= (uint16_t)Serial2.read() << 8;

    return n;
  }

  return 0;
}

float b2f(uint8_t* buff) {
  uint8_t nBuff[4] = { buff[3], buff[2], buff[1], buff[0] };

  static float value = 0;
  memcpy(&value, nBuff, 4);
  return value;
}

float read(uint16_t offset) {
  uint8_t buff[4];
  uint8_t n = readModbusRTU(44, 4, offset, 2, buff);
  if (n == 4) {
    return b2f(buff);
  }
  return -999.99;
}

void loop() {
  Serial.printf("Volt: %.02fV\n", read(0x0000));
  Serial.printf("Current: %.02fA\n", read(0x0008));
  Serial.printf("Active Power: %.02fkWh\n", read(0x0012));
  Serial.printf("Power Factor: %.02f\n", read(0x002A));
  Serial.printf("Frequency: %.02fHz\n", read(0x0036));
  Serial.printf("Total Active Power: %.02fkWh\n", read(0x0100));
  Serial.printf("---------------------------\n");
  delay(500);
}

รันแล้วขึ้น -999 อยากให้ช่วยดูหน่อยครับ ขอบคุณครับ