F_GetDayOfWeek

You can use this function to obtain the day of week represented by a specified date and time value. The function uses the ISO 8601 standard definition of a week. A week is considered to start a Monday = 1and end on Sunday = 7.

FUNCTION F_GetDayOfWeek : WORD

VAR_INPUT
    in : DT;
END_VAR

PROGRAM MAIN
VAR
    dtFirst : DT := DT#2008-01-01-00:00;
    dayOfWeek : WORD;
END_VAR

dayOfWeek := F_GetDayOfWeek(dtFirst);