Fixed bug in DATE_AND_TIME_TO_TIME_OF_DAY and DATE_AND_TIME_TO_DATE when date and time is before 1970-01-01-00:00:00
FUNCTION_BLOCK HYSTERESIS
(* Boolean hysteresis on difference *)
(* of REAL inputs, XIN1 - XIN2 *)
VAR_INPUT XIN1, XIN2, EPS : REAL; END_VAR
VAR_OUTPUT Q : BOOL := 0; END_VAR
IF Q THEN IF XIN1 < (XIN2 - EPS) THEN Q := 0; END_IF ;
ELSIF XIN1 > (XIN2 + EPS) THEN Q := 1 ;
END_IF ;
END_FUNCTION_BLOCK