上位機和下位機通信的問題，使用的協(xié)議rs485協(xié)議.

題目是用VC++讓上位機和下位機進行通信.

接在電腦上的rs232口，使用了232和485的轉換器，發(fā)送相應的數(shù)據(jù)格式，然后上位機接受相應的格式。

原代碼如下:

// TODO: Add your control notification handler code here

char buff[200];

CString str;

GetDlgItem(IDC_EDI_BUF) -> GetWindowText(str);

sprintf(buff,"%s",(LPCSTR)str);

//MessageBox(buff);

//然后打開串口,開始通信

HANDLE hCom; //createFile函數(shù)返回的句柄

//打開的是端口一

hCom = CreateFile("COM1",GENERIC_READ|GENERIC_WRITE,

0, NULL,OPEN_EXISTING, 0, NULL);

if(hCom == NULL)

{

MessageBox("打開端口一時出現(xiàn)了錯誤");

}

//設置讀寫緩沖區(qū)的緩沖大小

//改變端口的設備控制塊

/*DCB dcb;

GetCommState(hCom,&dcb);

dcb.BaudRate = CBR_9600;

dcb.ByteSize=8;//數(shù)據(jù)位8位

dcb.Parity = NOPARITY; //有校驗

dcb.StopBits=ONESTOPBIT; //一個停止位

if(false==SetCommState(hCom,&dcb))

{

MessageBox("配置端口時出現(xiàn)了錯誤");

}*/

DCB dcb;

GetCommState(hCom,&dcb);

dcb.BaudRate = CBR_9600;

dcb.ByteSize = 8;

dcb.Parity = NOPARITY;

dcb.StopBits = ONESTOPBIT;

dcb.fBinary = TRUE;

dcb.fParity = TRUE;

dcb.fOutxDsrFlow = false;

dcb.fDtrControl = DTR_CONTROL_DISABLE;

dcb.fOutxCtsFlow = false;

//#ifdef LPR_DOHERELARGE

// dcb.fRtsControl = RTS_CONTROL_ENABLE;

//#else

dcb.fRtsControl = RTS_CONTROL_DISABLE;

//#endif

/* dcb.fInX = false;

dcb.fOutX = false;

dcb.XonChar = ASCII_XON;

dcb.XoffChar = ASCII_XOFF;

dcb.XonLim = 100;

dcb.XoffLim = 100;*/

if(false==SetCommState(hCom,&dcb))

{

MessageBox("配置端口時出現(xiàn)了錯誤");

}

//設置讀寫操作,將緩沖里面的數(shù)據(jù)寫入到串口里面

BOOL isWrite = false;

DWORD length = 100;

COMSTAT ComStat;

DWORD dwErrorFlags;

ClearCommError(hCom,&dwErrorFlags,&ComStat);

isWrite = WriteFile(hCom,buff,length,&length,NULL);

if(isWrite == false)

{

MessageBox("寫入數(shù)據(jù)時出現(xiàn)了錯誤");

}

//寫完數(shù)據(jù)然后從緩沖里面讀取數(shù)據(jù)

//過一段時間才讀取緩沖里面的數(shù)據(jù)

::Sleep(100);

//讀取緩沖里面的數(shù)據(jù)

BOOL isRead = false;

char readbuf[100];

DWORD bReadStatus;

memset(readbuf,0,sizeof(readbuf));

isRead = ::ReadFile(hCom,readbuf,100,&bReadStatus,NULL);

//MessageBox(readbuf);

GetDlgItem(IDC_RECV_BUFF) -> SetWindowText(readbuf);

CloseHandle(hCom);

這樣就完成了一次通信。還有從下位機發(fā)送來的報文解析部分沒有給出。那部分是純的軟件部分。和機器無關。