Read MTM-380SD RS-232 data output

mtm-380sd.ino

#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11); // RX, TX

void setup() {
  Serial.begin(115200);
  mySerial.begin(9600);
}

uint8_t buffs[3][16];

void loop() { // run over and over
  if (mySerial.available() && mySerial.read() == 0x02) {
    while (!mySerial.available());
    if (mySerial.read() != '4') return;
  
    char buff[16];
    for (int j = 13; j >= 0; j--) {
      while (!mySerial.available());
      buff[j] = mySerial.read();
    }

    for (int j = 13; j >= 0; j--) {
      buffs[buff[13] - '0' - 1][j] = buff[j];
    }
  }
  
  if (Serial.available()) {
    Serial.read();

    for (int i = 0; i < 3; i++) {
      double val = 0;
      for (int j = 8; j >= 1; j--) {
        val *= 10;
        val += buffs[i][j] - '0';
      }
      if (buffs[i][10] == '1') { // Polarity
        val = -val;
      }
      for (int i = 0; i < buffs[i][9]- '0'; i++) { // Decimal Point
        val /= 10;
      }
      Serial.print(val, buffs[i][9]- '0');
      Serial.print(",");
    }
    Serial.println();
  }
}