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Determine if a comm port is available

{ This tip uses the API of Windows to determine if a this available certain COM. Port: COM1, COM2, COM3... } function ComPortAvailable(Port: PChar): Boolean; var DeviceName: array[0..80] of Char; ComFile: THandle; begin StrPCopy(DeviceName, Port); ComFile := CreateFile(DeviceName, GENERIC_READ or GENERIC_WRITE, 0, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); Result := ComFile <> INVALID_HANDLE_VALUE; CloseHandle(ComFile); end; procedure TForm1.Button1Click(Sender: TObject); begin if ComPortAvailable('COM1:') then ShowMessage('Port available') else ShowMessage('Port not available'); end;