在VC中使用DLL一般都是采用動(dòng)態(tài)聲明的方式,函數(shù)說明中給出的是Delphi的函數(shù)原型,
 
在VC中聲明時(shí)只要注意一下類型的對應(yīng)即可,Delphi中的longint類型對應(yīng)VC中的int類型
 
Delphi中的Pchar對應(yīng)VC中的char* ,下面給出主要函數(shù)的聲明:
 
在使用的文件的cpp中聲明一個(gè)句柄:
 
HINSTANCE hinstDLL;
 
用來標(biāo)識(shí)導(dǎo)入的動(dòng)態(tài)鏈接庫。
 
1)、按下例說明聲明相關(guān)各個(gè)函數(shù):(在cpp文件的頭處聲明)
 
typedef int (_stdcall *pOpen)(int nport, int BaudRate, int DataBits, char* Parity, int StopBits, char* User);
typedef int (_stdcall *pClose)(int nport);
typedef int (_stdcall *pSetDelay)(int value);
typedef int (_stdcall *pComTrue)(int nport);
typedef int (_stdcall *pComWork)(int nport);
 
typedef int (_stdcall *pRs)(int nport, int node);
typedef int (_stdcall *pWs)(int nport, int node, int State);
typedef int (_stdcall *pBitForced)(int nport, int node, int address, int Bit, int value, char* Area);
typedef int (_stdcall *pCancelAllF)(int nport, int node);
typedef int (_stdcall *pReadBit)(int nport, int node, int address, int Bit, int Count, char* Area, int* RxdBuffer);
typedef int (_stdcall *pReadInt)(int nport, int node, int address, int Count, char* Area, int* RxdBuffer);
typedef int (_stdcall *pWriteBit)(int nport, int node, int address, int Bit, int Count, char* Area, int* TxdBuffer);
typedef int (_stdcall *pWriteInt)(int nport, int node, int address, int Count, char* Area, int* TxdBuffer);
 
typedef int (_stdcall *pSet)(int nport, int node, int address, int Bit, char* Area);
typedef int (_stdcall *pReSet)(int nport, int node, int address, int Bit, char* Area);
typedef int (_stdcall *pReadDInt)(int nport, int node, int address, int Count, int* RxdBuffer);
typedef int (_stdcall *pReadFloat)(int nport, int node, int address, int Count, float* RxdBuffer);
typedef int (_stdcall *pWriteDInt)(int nport, int node, int address, int Count, int* TxdBuffer);
typedef int (_stdcall *pWriteFloat)(int nport, int node, int address, int Count, float* TxdBuffer);
 
typedef int (_stdcall *pBitBin)(int value, int Bitaddress);
typedef int (_stdcall *p32I_16h)(int value);
typedef int (_stdcall *p32I_16l)(int value);
typedef int (_stdcall *p16I_32I)(int valueH, int valueL);
typedef int (_stdcall *p32f_16h)(float value);
typedef int (_stdcall *p32f_16l)(float value);
typedef float (_stdcall *p16I_32f)(int valueH, int valueL);
typedef int (_stdcall *pInt16Unsign)(int value);
 
2)、建立動(dòng)態(tài)鏈接庫的新函數(shù)名:(在cpp文件的頭處聲明)
 
pOpen mOpen; 
pClose mClose;
pSetDelay mSetDelay;
pComTrue mComTrue;
pComWork mComWork;
 
pRs mRs;
pWs mWs;
pBitForced mBitForced;
pCancelAllF mCancelAllF;
pReadBit mReadBit;
pReadInt mReadInt;
pWriteBit mWriteBit;
pWriteInt mWriteInt;
 
pSet mSet;
pReSet mReSet;
pReadDInt mReadDInt;
pReadFloat mReadFloat;
pWriteDInt mWriteDInt;
pWriteFloat mWriteFloat;
 
pBitBin mBitBin;
p32I_16h m32I_16h;
p32I_16l m32I_16l;
p16I_32I m16I_32I;
p32f_16h m32f_16h;
p32f_16l m32f_16l;
p16I_32f m16I_32f;
pInt16Unsign mInt16Unsign;
 
3)、導(dǎo)入動(dòng)態(tài)鏈接庫,如例所示:(在cpp文件的OnInitDialog過程建立):
 
hinstDLL = LoadLibrary("Omron_fins.dll");
 
4)、判斷dll文件是否存在并聲明并建立動(dòng)態(tài)鏈接庫中的函數(shù)與新函數(shù)名的對應(yīng)關(guān)系,
 
如下:(在cpp文件的OnInitDialog過程建立):
 
   if (hinstDLL)
   {
      mOpen = (pOpen)GetProcAddress (hinstDLL,"finsComOpen");
      //mOpen = (pOpen)GetProcAddress (hinstDLL,"finsCvComOpen");  CV模式plc使用這個(gè)打開串口
      mClose = (pClose)GetProcAddress (hinstDLL,"finsComClose");
      mSetDelay = (pSetDelay)GetProcAddress (hinstDLL,"finsSetDelay");
      mComTrue = (pComTrue)GetProcAddress (hinstDLL,"finsComTrue");
      mComWork = (pComWork)GetProcAddress (hinstDLL,"finsComWork");
    
      mRs = (pRs)GetProcAddress (hinstDLL,"finsPlcRs");
      mWs = (pWs)GetProcAddress (hinstDLL,"finsPlcWs");
      mBitForced = (pBitForced)GetProcAddress (hinstDLL,"finsBitForced");
      mCancelAllF = (pCancelAllF)GetProcAddress (hinstDLL,"finsCancelAllF");
      mReadBit = (pReadBit)GetProcAddress (hinstDLL,"finsReadBit");
      mReadInt = (pReadInt)GetProcAddress (hinstDLL,"finsReadInt");
      mWriteBit = (pWriteBit)GetProcAddress (hinstDLL,"finsWriteBit");
      mWriteInt = (pWriteInt)GetProcAddress (hinstDLL,"finsWriteInt");
 
      mSet = (pSet)GetProcAddress (hinstDLL,"finsSet");
      mReSet = (pReSet)GetProcAddress (hinstDLL,"finsReSet");
      mReadDInt = (pReadDInt)GetProcAddress (hinstDLL,"finsReadDInt");
      mReadFloat = (pReadFloat)GetProcAddress (hinstDLL,"finsReadFloat");
      mWriteDInt = (pWriteDInt)GetProcAddress (hinstDLL,"finsWriteDInt");
      mWriteFloat = (pWriteFloat)GetProcAddress (hinstDLL,"finsWriteFloat");
 
     mBitBin = (pBitBin)GetProcAddress (hinstDLL,"DecBitBin");
     m32I_16h = (p32I_16h)GetProcAddress (hinstDLL,"Int32ToInt_16h");
     m32I_16l = (p32I_16l)GetProcAddress (hinstDLL,"Int32ToInt_16l");
     m16I_32I= (p16I_32I)GetProcAddress (hinstDLL,"Int16ToInt32");
     m32f_16h = (p32f_16h)GetProcAddress (hinstDLL,"Float32ToInt_16h");
     m32f_16l = (p32f_16l)GetProcAddress (hinstDLL,"Float32ToInt_16l");
     m16I_32f= (p16I_32f)GetProcAddress (hinstDLL,"Int16ToFloat32");
     mInt16Unsign = (pInt16Unsign)GetProcAddress (hinstDLL,"Int16Unsign");
  
     AfxMessageBox("Omron_fins.dll已成功載入!");
  }
  else
 {
    AfxMessageBox("沒找到Omron_fins.dll!");
    SendMessage(WM_CLOSE); 
  }
 
注:雙引號(hào)中為動(dòng)態(tài)鏈接庫中的原有函數(shù)名。
 
 
函數(shù)中用到了char*型參數(shù),這里介紹下char*與Cstring的相互轉(zhuǎn)換的函數(shù):
 
(1)char*->CString
 
char* sz;
CString str;
str.Format("%s",sz);  //可以用此函數(shù)將讀取的值轉(zhuǎn)成字符串
 
(2) CString -> char*
 
CString str;
char* sz = str.GetBuffer(0);//可將字符串轉(zhuǎn)成char*給函數(shù)賦值
 
5)、當(dāng)不再需要使用DLL時(shí)記得關(guān)閉串口及釋放動(dòng)態(tài)鏈接庫,(在OnDestroy事件中釋放)
 
 if(hinstDLL)
 {
   int k = mComTrue(mnport);
   if (k==1) 
   {
      mClose(mnport);
   }    
   FreeLibrary(hinstDLL);
 }