[ajvdelphi]

Hola
Yo uso esta funcion:
De Hexa a Binario:

Código Delphi [-]
function HextoBin(Hexadecimal:string):string;
const
     BCD: array [0..15] of string=
       ('0000','0001','0010','0011','0100','0101','0110','0111',
        '1000','1001','1010','1011','1100','1101','1110','1111');
var
   i:integer;
begin
   for i:=Length(Hexadecimal) downto 1 do
     Result:=BCD[StrToInt('$'+Hexadecimal[i])]+Result;
end;

ejemplo de llamada:

Código Delphi [-]
Label1.Caption:=HextoBin('FA');

De binario a hexa

Código Delphi [-]
function BinToHex(Binario:string):string;
const 
     BCD: array [0..15] of string=
       ('0000','0001','0010','0011','0100','0101','0110','0111',
        '1000','1001','1010','1011','1100','1101','1110','1111');
     HEX: array [0..15] of char=
       ('0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F');
var 
   i,n:integer;
   sTemp:string;
   sNibble:string;
begin 
   Result:='';
   sTemp:=Binario+Copy('000',1,Length(Binario) mod 4);
   for i:=0 to (Length(Binario) shr 2)-1 do 
   begin 
    sNibble:=Copy(sTemp,(i shl 2)+1,4);
    n:=8;
    while (sNibble <> BCD[n]) do 
      if sNibble < BCD[n] then Dec(n) else Inc(n);
    Result:=Result+HEX[n];
   end; 
end;

Llamada

Código Delphi [-]
Label1.Caption:=BintoHex('100011100100101011');

Saludos
Augusto