Hvordan udnyttes en event fra en underklasse?

TComport er installeret i VCL og foretager RS232 kommunikation, i dette tilfælde til en afstandsmåler.
OnRxFlag eventen ønskes ydnyttet i den vedlagte Unit1. OnRxFlag bliver kaldt når der modtages en bestemt karakter over Com1 porten.
Hvordan gøres dette?

TComPort = class(TComponent)
  private
    {..}
    FOnRxChar: TRxCharEvent;
    {..}
    procedure DoOnRxChar;
    {..}
  protected
  public
  published
    property OnRxFlag: TNotifyEvent read FOnRxFlag write FOnRxFlag;
  end;

(*****************************************)

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  TLaser = class(TComport)
  private
    Korrektion : Integer;
  public
    Constructor Init(Nr : Integer);
    function SkrivVar : Integer;
  published
  end;

var
  Form1: TForm1;
  Laser: array [1..2] of TLaser;

implementation

{$R *.DFM}

Constructor TLaser.Init(Nr : Integer);
begin
  Korrektion:=1000;
  Create(Laser[Nr]);
  if Nr=1 then Port:=COM1 else port:=COM2;
  BaudRate:=br9600;
  DataBits:=dbEight;
  EventChar:=10;
end;

function TLaser.SkrivVar : Integer;
begin
  Result:=Korrektion;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Laser[1]:=TLaser.Init(1);
  Edit1.Text:=IntToStr(Laser[1].SkrivVar);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  Laser[1].Open;
  Laser[1].WriteString('g'+chr(13),True);
end;

end.