unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Unit2, ExtCtrls, IdBaseComponent, IdComponent,
  IdTCPConnection, IdTCPClient;

type
  TForm1 = class(TForm)
    Button1: TButton;
    IdTCPClient1: TIdTCPClient;
    procedure FormCreate(Sender: TObject);
  private
    Main : TMain;
  public
    Time:string;
  end;

var
  Form1: TForm1;

implementation
{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
Main := TMain.Create(tpnormal);
end;

end.

unit Unit2;

interface

uses
  Classes, ExtCtrls, WinSock, SysUtils, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient;

type
  TMain = class(TThread)
  IdTCPClient: TIdTCPClient;
  Timer1: TTimer;
  private

  protected
    procedure Execute; override;
    procedure Update;
  public
   constructor Create(ThreadPriority: TThreadPriority);
  end;

implementation
uses Unit1;

{ Wichtig: Methoden und Eigenschaften von Objekten in visuellen Komponenten dürfen
  nur in einer Methode namens Synchronize aufgerufen werden, z.B.

      Synchronize(UpdateCaption);

  und UpdateCaption könnte folgendermaßen aussehen:

    procedure Main.UpdateCaption;
    begin
      Form1.Caption := 'Aktualisiert in einem Thread';
    end; }

{ Main }

constructor TMain.Create(ThreadPriority: TThreadPriority);
Begin
inherited Create(false);
Priority:=ThreadPriority;
end;

procedure TMain.Execute;
begin
Timer1.Create(nil);
IdTCPClient.Create(nil);
with IdTCPClient do
Begin
ASCIIFilter:=false;
MaxLineLength:=16384;
ReadTimeOut:=0;
RecvBufferSize:=32768;
SendBufferSize:=32768;
end;
with Timer1 do
Begin
enabled:=true;
Interval:=1000;
end;
  try
  IdTCPClient.Connect(100);
  except
  end;

Synchronize(Update);
end;

procedure TMain.Update;
begin
  Form1.caption := '00:00:00';
end;

end.