1  FUNCTION_BLOCK AVERAGE

     2    VAR_INPUT

     3      RUN : BOOL ;      (* 1 = run, 0 = reset *)

     4      XIN : REAL ;     (* Input variable *)

     5      N   : INT ;      (* 0 <= N < 128 or manufacturer- *)

     6    END_VAR            (*      specified maximum value  *)

     7    VAR_OUTPUT XOUT : REAL ; END_VAR (* Averaged output *)

     8    VAR SUM  : REAL := 0.0; (* Running sum *)

     9        FIFO : DELAY ;      (* N-Element FIFO *)

    10    END_VAR

    11    SUM := SUM - FIFO.XOUT ;

    12    FIFO (RUN := RUN , XIN := XIN, N := N) ;

    13    SUM := SUM + FIFO.XOUT ;

    14    IF RUN THEN XOUT := SUM/N ;

    15    ELSE SUM := N*XIN ; XOUT := XIN ;

    16    END_IF ;

    17  END_FUNCTION_BLOCK

    18