Qdo o usr terminar de digitar o código (4 caracteres)....

Oi Debora, faça o seguinte:

if lenght(edit1.text) = 4 then
edit2.setfocus;

Um abraço

Poeta Noturno

Valeu!

exemplo :

edite o maxlength do edit1 para 4.

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;

type
TForm1 = class(TForm)
Edit1: TEdit;
Edit2: TEdit;
procedure Edit1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;
x: integer;

implementation

{$R *.DFM}

procedure TForm1.Edit1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
if Edit1.Text = ´´ then x:=0;
x:= x + 1;
if Edit1.MaxLength = x then
Edit2.setFocus;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
x:= 0;
end;

end.