String Worda = "plcommpro.dll";
	wchar_t* plcommpro = Worda.w_str();
	hDLL = LoadLibrary(plcommpro);
	if (!hDLL) {
	  ShowMessage("Невозможно загрузить plcommpro.dll");
	  return;
	}

кнопкой вызываю функцию подключения:
        typedef int (__cdecl * Connectos)(const char *param);
	Connectos Connect = (Connectos)GetProcAddress(hDLL, "Connect");
	//String W = "protocol=TCP,ipaddress=" +Edit1->Text+ ",port=4370,timeout=2000,passwd=";
	//wchar_t* ytt = W.w_str();
	const char *Parameters = "protocol=TCP,ipaddress=192.168.5.48,port=4370,timeout=2000,passwd="; // 192.168.5.48
	int h = Connect(Parameters);
	if (h != 0)
	{
		StaticText1->Caption = "Подключено";
		isConnect = true;
		Edit1->Enabled = false;
	}
	else
	{
		StaticText1->Caption = "не Подключено";
		isConnect = false;
		Edit1->Enabled = true;
	}

if (isConnect)
	{
		typedef int (__cdecl * EP)(void);
		EP ExecProc = (EP)GetProcAddress(hDLL, "Disconnect");
		int h = ExecProc();
		StaticText1->Caption = "неПодключено";
		isConnect = false;
		Edit1->Enabled = true;
	}

.2 Disconnect
[Function]
Void Disconnect(HANDLE handle)
[Objective]
The function is used to disconnect the device.
[Parameter description]
handle
[in]: The handle that is returned when the connection is successful.
[Returned value]
None
[Example]
Python:
self.commpro.Disconnect(self.hcommpro)
self.hcommpro = 0
c#:
Disconnect(h);
h = IntPtr.Zero;