#define RY1_pin 2
#define RY2_pin 3
#define RY3_pin 4
#define RY4_pin 5
#define RY5_pin 6
#define RY6_pin 7
#define RY7_pin 8
#define RY8_pin 9
bool CmdComplete = false; // whether the string is complete
void setup() {
pinMode(RY1_pin,OUTPUT);
pinMode(RY2_pin,OUTPUT);
pinMode(RY3_pin,OUTPUT);
pinMode(RY4_pin,OUTPUT);
pinMode(RY5_pin,OUTPUT);
pinMode(RY6_pin,OUTPUT);
pinMode(RY7_pin,OUTPUT);
pinMode(RY8_pin,OUTPUT);
Serial.begin(9600);
Serial.print("Please...Wrinte RY01N or RY01F");
}
void loop() 
{
if(CmdComplete) 
  {
    CmdComplete = false;
    myRelayControl(); // Please wait in NextStep 😊
  }
}

unsigned char RxBuff[16];
unsigned char RxCount = 0 ;
void serialEvent(){
  while(Serial.available()) 
  {
    // get the new byte:
    
    unsigned char inChar = (char)Serial.read(); 
    RxBuff[RxCount] = inChar;
    Serial.write(RxBuff[RxCount]);
    if(RxBuff[0] == 'R') 
    {
      if((RxCount==4) || (RxBuff[RxCount] == '#')) 
      {
        CmdComplete = true;
        RxCount = 0; return;
      }
     // Serial.print(RxCount);
      RxCount++;      
    }      
  }
}
void myRelayControl(void)
{ //------ RYnnN , RYnnF
  if((RxBuff[1] == 'Y') && (RxBuff[2] == '0'))
  {
//------ Relay Channel Number is 1 ----------
    if(RxBuff[3] == '1')
    {
       if(RxBuff[4] == 'T') digitalWrite(RY1_pin,HIGH);
       if(RxBuff[4] == 'F') digitalWrite(RY1_pin,LOW);
    }
//------ Relay Channel Number is 2 ----------
    if(RxBuff[3] == '2')
    {
       if(RxBuff[4] == 'T') digitalWrite(RY2_pin,HIGH);
       if(RxBuff[4] == 'F') digitalWrite(RY2_pin,LOW);
    }
  //------ Relay Channel Number is 3 ----------
    if(RxBuff[3] == '3')
    {
       if(RxBuff[4] == 'T') digitalWrite(RY3_pin,HIGH);
       if(RxBuff[4] == 'F') digitalWrite(RY3_pin,LOW);
    }
  //------ Relay Channel Number is 4 ----------
    if(RxBuff[3] == '4')
    {
       if(RxBuff[4] == 'T') digitalWrite(RY4_pin,HIGH);
       if(RxBuff[4] == 'F') digitalWrite(RY4_pin,LOW);
    }
  //------ Relay Channel Number is 5 ----------
    if(RxBuff[3] == '5')
    {
       if(RxBuff[4] == 'T') digitalWrite(RY5_pin,HIGH);
       if(RxBuff[4] == 'F') digitalWrite(RY5_pin,LOW);
    }
  //------ Relay Channel Number is 6 ----------
    if(RxBuff[3] == '6')
    {
       if(RxBuff[4] == 'T') digitalWrite(RY6_pin,HIGH);
       if(RxBuff[4] == 'F') digitalWrite(RY6_pin,LOW);
    }
  //------ Relay Channel Number is 7 ----------
    if(RxBuff[3] == '7')
    {
       if(RxBuff[4] == 'T') digitalWrite(RY7_pin,HIGH);
       if(RxBuff[4] == 'F') digitalWrite(RY7_pin,LOW);
    }
  //------ Relay Channel Number is 8 ----------
    if(RxBuff[3] == '8')
    {
       if(RxBuff[4] == 'T') digitalWrite(RY8_pin,HIGH);
       if(RxBuff[4] == 'F') digitalWrite(RY8_pin,LOW);
    }
  }
}