etisserant@0:  FUNCTION_BLOCK DIFFEQ
etisserant@0:    VAR_INPUT
etisserant@0:      RUN : BOOL ;             (* 1 = run, 0 = reset *)
etisserant@0:      XIN : REAL ;
etisserant@0:      A : ARRAY[1..] OF REAL ; (* Input coefficients *)
etisserant@0:      M : INT ;                (* Length of input history  *)
etisserant@0:      B : ARRAY[0..] OF REAL ; (* Output coefficients *)
etisserant@0:      N : INT ;                (* Length of output history *)        
etisserant@0:    END_VAR
etisserant@0:    VAR_OUTPUT XOUT : REAL := 0.0 ; END_VAR
etisserant@0:    VAR  (* NOTE : Manufacturer may specify other array sizes *)   
etisserant@0:      XI : ARRAY [0..128] OF REAL ; (* Input history  *)
etisserant@0:      XO : ARRAY [0..128] OF REAL ; (* Output history *)
etisserant@0:      I : INT ;
etisserant@0:    END_VAR
etisserant@0:    XO[0] := XOUT ; XI[0] := XIN ;
etisserant@0:    XOUT := B[0] * XIN ;
etisserant@0:    IF RUN THEN
etisserant@0:       FOR I := M TO 1 BY -1 DO
etisserant@0:           XOUT := XOUT + A[I] * XO[I] ; XO[I] := XO[I-1];
etisserant@0:       END_FOR;
etisserant@0:       FOR I := N TO 1 BY -1 DO
etisserant@0:           XOUT := XOUT + B[I] * XI[I] ; XI[I] := XI[I-1];
etisserant@0:       END_FOR;
etisserant@0:    ELSE
etisserant@0:       FOR I := 1 TO M DO XO[I] := 0.0; END_FOR;
etisserant@0:       FOR I := 1 TO N DO XI[I] := 0.0; END_FOR;
etisserant@0:    END_IF ;
etisserant@0:  END_FUNCTION_BLOCK
etisserant@0: