Advent first sunday

Hello Marosz,

unfortunately, there is not such function in Mosaic libraries. I can try to figure out how to count off the four weeks from Christmas Day.

Function for estamination of the first advent by the year may look like this (TimeLib is required for proper function):

FUNCTION GetFirstAdventSundayDate : DATE
(*
  Get date of the first advent sunday for years 2000 - 2099
*)
  VAR_INPUT
    year : UINT;
  END_VAR
  VAR_IN_OUT
  END_VAR
  VAR
    tdt : TTecoDateTime;
    idt2 : DT;
  END_VAR
  VAR_TEMP
  END_VAR

  IF year < 2000 OR year > 2099 THEN
    year := YEAR_OF_DATE(GetDate());
  END_IF;

  tdt.day := 27;
  tdt.month := 11;
  tdt.year := UINT_TO_USINT(year-2000);
  
  idt2 := TecoDT_TO_DT(Teco_DT := tdt);
  tdt := DT_TO_TecoDT(IEC_DT := idt2);
  GetFirstAdventSundayDate := LREAL_TO_DATE(DATE_AND_TIME_TO_LREAL(idt2) + USINT_TO_LREAL(7 - tdt.dayOfWeek)*86400.0);

END_FUNCTION

Thank you for your time!
I made this program.
Unfortunately, this only indicates that day
 

VAR
 christmas_number        : UINT := 359;
 today_number            : UINT;
 Days_to_christmas       : UINT;
 today                   : UINT; //hét napjai
 future_day_of_week      : UINT; //hét napjai
 ADVENT                  : BOOL;
 end_var



 today_number := DAY_OF_YEAR(in :=GetDate());
 Days_to_christmas := (christmas_number - today_number);
 today := usint_to_uint(System_S.COUNTER_DAYS_OF_WEEK);
 future_day_of_week := (Days_to_christmas + (today - 1)) / 7;
 If future_day_of_week = 4 AND today = 7 Then
    ADVENT := True;
 Else
    ADVENT := False;
 End_if;
 
END_PROGRAM