Comments not to do with your problem or resolution.  Just how to use the forums to post code, and in particular SCL blocks.

To post code, what I do is type some random garbage like asdf, highlight it, then click the "Mark as code" open above the text entry box.

Now I highlight that random garbage, select all the code I want to post (preferably in notepad or something that does not insert CR / LF or tab keys and such), and then paste my copied code over top my random asdf.

 This

asdf

 becomes

(* Push onto stack *)
#stack[#stack_count] := #last;   (* right part, sort later *)
IF #stack_count < 32 THEN
#stack_count := #stack_count + 1;
ELSE
#end_outer := TRUE;
#SORT := FALSE;         (* Error: Stack too small *)
END_IF;

and because it is marked as code, I can turn that into properly indented (easier to read structures) SCL:

// Push onto stack
#stack[#stack_count] := #last;   // right part, sort later
IF #stack_count < 32 THEN
   #stack_count := #stack_count + 1;
ELSE
   #end_outer := TRUE;
   #SORT := FALSE;         // Error: Stack too small
END_IF;

And because we can generate the code that makes it really easy to import into a project, we can post the entire scl, interface, and all the attributes, title, description, and all as well.

(*http://www.oscat.dewith google translate to translate DE to EN *)
(* @PATH := '/Engineering/control' *)

FUNCTION DEAD_BAND : REAL
TITLE = 'DEAD_BAND'
//
//DEAD_BAND is a linear Transfer function with deadband. The function shifts the positive part of the curve by + L and the negative part of the curve by -L.
//DEAD_BAND = X - L when X > L)
//DEAD_BAND = X + L when X < -L
//DEAD_BAND = 0 when Abs(X) <= L
//
VERSION : 1.2
AUTHOR  : hugo
NAME    : DEADBAND
FAMILY  : CTRL

VAR_INPUT
  X : REAL;
  L : REAL;
END_VAR

BEGIN

  IF X > L THEN
    DEAD_BAND := X - L;
  ELSIF X < -L THEN
    DEAD_BAND := X + L;
  ELSE
    DEAD_BAND := 0.0;
  END_IF;

(* revision history
hm  2. nov. 2007  rev 1.0
original version

hm  14. jun. 2008 rev 1.1
improved performance

hm  18. jan. 2011 rev 1.2
assign 0 before return
*)
END_FUNCTION

You can copy the above block of text, paste into notepad, save as DEAD_BAND.SCL, and use it to generate the scl source in TIA Portal.  It may be missing some tia portal scl features.  If you create a FC without anything other than the above interface manually, you can right-click and "copy as text" and paste into notepad to see the equivalent without the actual logic part.

This is part of the OSCAT open source library found at www.oscat.de (google translate may come in handy for some people).