void setup() {
   Serial.begin(9600);
   Serial.println("hello"); 
}
 
String mes1,cmd,dat;
int dat1,dat2,dat3;
bool f_serial = false;
int index1,index2;
float volt;
void loop() {
  if(f_serial == 1){  //RGB 10,20,40/
     f_serial = 0;
     Serial.println(mes1);  //RGB 10,20,40
 
     index1 = mes1.indexOf(' ');  //RGB 10,20,40
     cmd = mes1.substring(0,index1);
     Serial.print("cmd=");    
     Serial.println(cmd);  //RGB
 
     index1 = index1+1; //ตำแหน่งตัว 1 ได้เลขตำแหน่งที่5        
     index2 =  mes1.indexOf(',');//ตำแหน่งตัว , ได้เลขตำแหน่งที่6
     dat = mes1.substring(index1,index2); // (5,6)
     dat1 = dat.toInt();
     dat = "";
     Serial.print("dat1=");
     Serial.println(dat1);  //10
 
     index1 = index2+1; //ตำแหน่งตัว2
     index2 =  mes1.indexOf(',',index1);//ตำแหน่งตัว ,
     dat = mes1.substring(index1,index2);
     dat2 = dat.toInt();
      dat = "";
     Serial.print("dat2=");
     Serial.println(dat2);//20
 
     index1 = index2+1; //ตำแหน่งตัว4
    dat = mes1.substring(index1); //”40”
     dat3 = dat.toInt();
      dat = "";
     Serial.print("dat3=");
     Serial.println(dat3); //40  
     mes1="";
 
   if(cmd =="rgb"){
       //your code
       //analogWrite(11,255-dat1);//r
       //analogWrite(10,255-dat2);//g
       //analogWrite(9,255-dat3);//b
    }else if(cmd == "read"){
       //your code
 
    }   
  }    
}
void serialEvent() {
  while (Serial.available()) {  //RGB 1,50,100/
    char inChar = (char)Serial.read();    
    if (inChar != '\n') {
      mes1 += inChar;      //“RGB 1,50,100”
    }else{      
      f_serial = true;
    }
  }
}