#include <SoftwareSerial.h>
#define SSerialRX        10
#define SSerialTX        11
#define SSerialTxControl 3
#define RS485Transmit    HIGH
#define RS485Receive     LOW

SoftwareSerial RS485Serial(SSerialRX, SSerialTX); // RX, TX

struct mydata {
  char cmd;
  int count;
  float temp;
  char str[20];
};
mydata dato = {'x', 0, 18.0f, "hello world!"};

void setup() {
  RS485Serial.begin(4800);
 Serial.begin(9600);
  pinMode(13, OUTPUT);
  pinMode(SSerialTxControl, OUTPUT);
  digitalWrite(SSerialTxControl, RS485Receive);  // Init Transceiver
}
void loop() {

  if (RS485Serial.available()) {
    byte n = RS485Serial.read();
    if (n == 0) {
      Serial.println("req");
  digitalWrite(13, HIGH);
  readSensor();
    }

   }
}
  void readSensor(){
  digitalWrite(SSerialTxControl, RS485Transmit);
  RS485Serial.write((const uint8_t *)&dato, sizeof(struct mydata));
  RS485Serial.write((byte)'\n');
  dato.count++;
  delay(250);
  digitalWrite(SSerialTxControl, RS485Receive);
digitalWrite(13, LOW);
Serial.print("dato.count"); Serial.println(dato.count);
}