etisserant@0:  FUNCTION_BLOCK LAG1
etisserant@0:    VAR_INPUT
etisserant@0:      RUN : BOOL ;     (* 1 = run, 0 = reset *)
etisserant@0:      XIN : REAL ;     (* Input variable *)
etisserant@0:      TAU : TIME ;     (* Filter time constant *)
etisserant@0:      CYCLE : TIME ;   (* Sampling time interval *)
etisserant@0:    END_VAR
etisserant@0:    VAR_OUTPUT XOUT : REAL ; END_VAR  (* Filtered output *)
etisserant@0:    VAR K : REAL ;     (* Smoothing constant, 0.0<=K<1.0 *)
etisserant@0:    END_VAR
etisserant@0:    IF RUN THEN XOUT := XOUT + K * (XIN - XOUT) ;
etisserant@0:    ELSE XOUT := XIN ;
etisserant@0:         K := TIME_TO_REAL(CYCLE) / TIME_TO_REAL(CYCLE + TAU) ;
etisserant@0:    END_IF ;
etisserant@0:  END_FUNCTION_BLOCK
etisserant@0: