procedure TForm1.Button1Click(Sender: TObject);

var

 CommPort : string;

 hCommFile : THandle;

 ModemStat : DWord;

begin

 CommPort := 'COM2';

{Открываем com-порт}

 hCommFile := CreateFile(PChar(CommPort),

  GENERIC_READ,

  0,

  nil,

  OPEN_EXISTING,

  FILE_ATTRIBUTE_NORMAL,

  0);

 if hCommFile = INVALID_HANDLE_VALUE then

 begin

  ShowMessage('Unable to open '+ CommPort);

  exit;

 end;

{Получаем состояние модема}

 if GetCommModemStatus(hCommFile, ModemStat) <> false then begin

  if ModemStat and MS_CTS_ON <> 0 then

  ShowMessage('The CTS (clear-to-send) is on.');

  if ModemStat and MS_DSR_ON <> 0 then

  ShowMessage('The DSR (data-set-ready) is on.');

  if ModemStat and MS_RING_ON <> 0then

  ShowMessage('The ring indicator is on.');

  if ModemStat and MS_RLSD_ON <> 0 then

  ShowMessage('The RLSD (receive-line-signal-detect) is

on.');

end;

{Закрываем com-порт}

 CloseHandle(hCommFile);

end;