//+------------------------------------------------------------------+
//|                                                     TFChange.mq4 |
//|                                              Copyright 2020, AM2 |
//|                                      http://www.forexsystems.biz |
//+------------------------------------------------------------------+
#property copyright "Copyright 2019, AM2"
#property link      "http://www.forexsystems.biz"
#property version   "1.00"
#property strict
#property indicator_chart_window

input int sec=20;

input ENUM_TIMEFRAMES tf1=PERIOD_H4; // период куда переключаем
input ENUM_TIMEFRAMES tf=PERIOD_H1;  // текуший период

int i=0;
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- indicator buffers mapping
   Comment("");
//--- создадим таймер с периодом в 1 секунду
   EventSetTimer(1);
//---
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
  {
//--- уничтожим таймер при завершении работы
   EventKillTimer();
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const int &spread[])
  {
//---

//--- return value of prev_calculated for next call
   return(rates_total);
  }
//+------------------------------------------------------------------+
//| Timer function                                                   |
//+------------------------------------------------------------------+
void OnTimer()
  {
   i++;

   if(i>sec)
     {
      if(Period()!=tf1)
        {
         ChartSetSymbolPeriod(0,NULL,tf1);
         ChartSetSymbolPeriod(0,NULL,tf);
         i=0;
         return;
        }
     }

   Comment("\n Sec: ",i);
  }
//+------------------------------------------------------------------+