udp-client.pas

procedure TForm2.Button1Click(Sender: TObject);
  var
    iType: Integer;
    buf: array[0..8191] of char;
    UDP: TidUDPClient;
begin
  UDP := TIdUDPClient.Create(nil);
  try
    UDP.Host := '127.0.0.1';
    UDP.Port := 1108;
    UDP.Active := True;
    FillChar(buf, 8192, 0);
    iType := 1001;
    CopyMemory(@buf[0], @iType, 4);
    CopyMemory(@buf[4], @Edit1.Text[1], Length(Edit1.Text));
    UDP.SendBuffer(buf, Length(Edit1.Text)+4);
    UDP.ReceiveTimeout := 3000;
    Memo1.Lines.Add(UDP.ReceiveString());
  finally
    UDP.Free;
  end;
end;