// first-order lag derivative term (*
Parameter K must be set to T / (T + T1)
*) FUNCTION_BLOCK DT2
VAR_INPUT
IN : REAL; K : REAL;
END_VAR VAR_OUTPUT
Q : REAL;
END_VAR VAR
H : REAL := 0.0;
END_VAR
BEGIN
Q := IN - H; H := H + K * Q;
END_FUNCTION_BLOCK