vb调用vc编写的dll文件，怎么调用在vc的dll中的类成员函数

// The following ifdef block is the standard way of creating macros which make exporting 
// from a DLL simpler. All files within this DLL are compiled with the OMRONPC_EXPORTS
// symbol defined on the command line. this symbol should not be defined on any project
// that uses this DLL. This way any other project whose source files include this file see 
// OMRONPC_API functions as being imported from a DLL, wheras this DLL sees symbols
// defined with this macro as being exported.
#ifdef OMRONPC_EXPORTS
#define OMRONPC_API __declspec(dllexport)
#else
#define OMRONPC_API __declspec(dllimport)
#endif
//
//This .dll is used to connect the PC and OMRON PLC;
//Created by Liu Daxin :liucgq@163.com
//用法：先创建一个COmronPC类，然后先用ComInit来初始化com口，再用PLCToConnect()链接plc
//然后可以在timer中加入ReadAndWritePLC()来完成读写
//
//
//
//
//
// This class is exported from the OmronPC.dll
class OMRONPC_API COmronPC {
public:
    void ReadAndWritePLC(char* readaddr="15",char readlenth='2',char* returnstr="");//前面的是需要读的首地址例如15.00,后面是返回的字符串
    void WriteOnOff(char* addr, int sta);
    void StopTimer();
    void StartWriteTimer(UINT mmtime=100);
    static void CALLBACK TimeProcSend(UINT uID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2);
    void WriteSingleOnOffToPLC(char* addr,int sta);//addr为“1500”或“1715”等，可以打开或关闭相应的位
    void StopPLC();
    void PLCToConnect();
    void ReadFromPLC(char * str);
    void WriteToPLC(char OutDat[8]);
    HANDLE m_hCom;
    DCB dcb;
    void ComInit(char* port="COM1",long baurate=9600,int parityint=EVENPARITY,int bytsize=7,int stopbits=TWOSTOPBITS);
    //EVENPARITY 偶校验 ,NOPARITY 无校验 
    //MARKPARITY 标记校验   ODDPARITY 奇校验 
    //dcb.ByteSize = 7;//数据位 
    // ONESTOPBIT 1位停止位   
    //TWOSTOPBITS 2位停止位 
    //ONE5STOPBITS 1.5位停止位 
    COmronPC(void);
    char PLCReturn[30];
    // TODO: add your methods here.
private:
    char OutDat[21][4];
    unsigned long OutLong[21];
    HANDLE h_mutex;
    MMRESULT TimeID;
};

extern "C" OMRONPC_API int nOmronPC;

extern "C" OMRONPC_API int fnOmronPC(void);

Declare Sub ComInit Lib "OmronPC.dll" Alias "?ComInit@COmronPC@@QAEXPADJHHH@Z" ( _
ByRef comn As String, _
bute As Long, _
parity As Integer, _
butsize As Integer, _
stopbits As Integer)