#include <SoftwareSerial.h>
#include <Wire.h>
#define RE D5
#define DE D6
 
const byte O2[] = {0x01 ,0x03 ,0x00 ,0x00 ,0x00 ,0x02 ,0xC4 ,0x0B};
 
byte values[20];
SoftwareSerial mod(D7, D8); // RO / DI
 
void setup() {
Serial.begin(9600);
mod.begin(4800);
pinMode(RE, OUTPUT);
pinMode(DE, OUTPUT);
}
 
void loop() {
  int val1 = 0 ;
  Calculate();
  val1 = values[4];
  Serial.print("v: ");
  Serial.println(val1);

  delay(1000);
}

 
byte Calculate() {
digitalWrite(DE, HIGH);
digitalWrite(RE, LOW);
delay(10);
if (mod.write(O2, sizeof(O2)) == 8) {
digitalWrite(DE, LOW);
digitalWrite(RE, LOW);
for (byte i = 0; i < 11; i++) {
//Serial.print(mod.read(),HEX);
values[i] = mod.read();
//Serial.print(values[i], HEX);
//Serial.print(" ");
}
Serial.println();
}
return values[6];
}