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(shuō)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(duì)應(yīng)即可,Delphi中的longint類型對(duì)應(yīng)VC中的int類型
Delphi中的Pchar對(duì)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(lái)標(biāo)識(shí)導(dǎo)入的動(dòng)態(tài)鏈接庫(kù)。
1)、按下例說(shuō)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(kù)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(kù)，如例所示：(在cpp文件的OnInitDialog過(guò)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(kù)中的函數(shù)與新函數(shù)名的對(duì)應(yīng)關(guān)系，
如下：(在cpp文件的OnInitDialog過(guò)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(kāi)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(méi)找到Omron_fins.dll！");
SendMessage(WM_CLOSE);
}
注：雙引號(hào)中為動(dòng)態(tài)鏈接庫(kù)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(kù)，(在OnDestroy事件中釋放)
if(hinstDLL)
{
int k = mComTrue(mnport);
if (k==1)
{
mClose(mnport);
}
FreeLibrary(hinstDLL);
}
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