void Communication()
{
   
  // checking for incoming data on the serial port 
   if (Serial.available() > 0)
   {
      _array_in[index] = Serial.read();
      index= index+1; 
   }
// the Protocol provides for the arrival of 2 bytes. 
// if the first byte is 0x00 ITV1 will be activated and it will output the pressure value indicated on the second byte.
// if the first byte is different from 0x00 the pressure sensor will be activated.
      if (index >1)                     
      {   
         switch (_array_in[0])    
           {        
             case 0xFF:
            
              mes_in = _array_in[1];    
              index = 0;
              
              
          
              break; 
             Serial.flush();  
              
              case 0x00:
                 index = 0;
                 _array_out2[0] = 0xFF;
                 _array_out2[1] = _invio;
                 Serial.write(_array_out2,2);
              break;
              Serial.flush();
                 } 
            }     
}
