Help me for signal alert

[GBENYANAWO]

I WANT TO CREATE AN ALERT SYSTEM WHEN RSI=50

JUST it without  repeating alert a lot of time.

please help me

//+------------------------------------------------------------------+

//|                                                       ALERTE.mq5 |

//|                           Copyright 2019, IB TECH Software Corp. |

//|                                             https://www.mql5.com |

//+------------------------------------------------------------------+

#property copyright "Copyright 2019, IB TECH Software Corp."

#property link      "https://www.mql5.com"

#property version   "1.00"

int iRSI;

int PeriodRsi;

double rsi=iRSI(NULL,0,21,0);

//+------------------------------------------------------------------+

//| Script program start function                                    |

//+------------------------------------------------------------------+

void OnStart()

  {

//---Alerte condition

   if (rsi=50)

   {PlaySound("Alert.wav");}

   else

   {PlaySound(NULL);}

   

  }

//+------------------------------------------------------------------+