Correctly identify errors when parsing erroneous code (make sure flex goes back to INITIAL state when code contains errors that do not allow determining whether ST or IL is being parsed)
(* Following taken directly from the IEC 61131.3 draft standard *)
(*
* An IEC 61131-3 IL and ST compiler.
*
* Based on the
* FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
*
*)
FUNCTION_BLOCK RAMP
VAR_INPUT
RUN : BOOL ; (* 0 - track X0, 1 - ramp to/track X1 *)
X0,X1 : REAL ;
TR : TIME ; (* Ramp duration *)
CYCLE : TIME ; (* Sampling period *)
END_VAR
VAR_OUTPUT
BUSY : BOOL ; (* BUSY = 1 during ramping period *)
XOUT : REAL := 0.0 ;
END_VAR
VAR XI : REAL ; (* Initial value *)
T : TIME := T#0s; (* Elapsed time of ramp *)
END_VAR
BUSY := RUN ;
IF RUN THEN
IF T >= TR THEN BUSY := 0 ; XOUT := X1 ;
ELSE XOUT := XI + (X1-XI) * TIME_TO_REAL(T)
/ TIME_TO_REAL(TR) ;
T := T + CYCLE ;
END_IF ;
ELSE XOUT := X0 ; XI := X0 ; T := t#0s ;
END_IF ;
END_FUNCTION_BLOCK