--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/AnnexF/derivative_st.txt Wed Jan 31 15:32:38 2007 +0100
@@ -0,0 +1,18 @@
+ FUNCTION_BLOCK DERIVATIVE
+ VAR_INPUT
+ RUN : BOOL ; (* 0 = reset *)
+ XIN : REAL ; (* Input to be differentiated *)
+ CYCLE : TIME ; (* Sampling period *)
+ END_VAR
+ VAR_OUTPUT
+ XOUT : REAL ; (* Differentiated output *)
+ END_VAR
+ VAR X1, X2, X3 : REAL ; END_VAR
+ IF RUN THEN
+ XOUT := (3.0 * (XIN - X3) + X1 - X2)
+ / (10.0 * TIME_TO_REAL(CYCLE)) ;
+ X3 := X2 ; X2 := X1 ; X1 := XIN ;
+ ELSE XOUT := 0.0; X1 := XIN ; X2 := XIN ; X3 := XIN ;
+ END_IF ;
+ END_FUNCTION_BLOCK
+