MFC 串口编程实例

VC串口编程从实现方法上一般分为两种，一种使用MSCOMM控件，这种方法比较简单，软件的移植性较低，在这里介绍一种串口封装类的使用方法。

代码

先看代码 CommUtils.cpp

#include "stdafx.h"
#include "CommUtils.h"
#include "stdio.h"
const int READ_TIMEOUT = 500;

CommUtils::CommUtils()
{
    bOpenCom = false;
}

CommUtils::~CommUtils()
{
    this->CloseCom();
}

bool CommUtils::OpenCom(int Port)
{
    if (bOpenCom)
    {
        this->CloseCom();
        bOpenCom = false;
    }
    char szport[10];
    sprintf(szport,"COM%d",Port);
    hComm = CreateFile( szport,GENERIC_READ|GENERIC_WRITE, 0,NULL,OPEN_EXISTING,FILE_FLAG_OVERLAPPED,NULL);
    int error=GetLastError();

    if (hComm == INVALID_HANDLE_VALUE)        return false;
    if (!SetupComm(hComm, 1024, 512))        return false;

    COMMTIMEOUTS commtimeouts;
    commtimeouts.ReadIntervalTimeout = MAXDWORD;
    commtimeouts.ReadTotalTimeoutConstant =0;
    commtimeouts.ReadTotalTimeoutMultiplier =0;
    commtimeouts.WriteTotalTimeoutConstant =0;
    commtimeouts.WriteTotalTimeoutMultiplier=0;

    if (!SetCommTimeouts(hComm, &commtimeouts))        return false;

    memset(&ReadovReady,0,sizeof(OVERLAPPED));
    memset(&WriteovReady,0,sizeof(OVERLAPPED));
    ReadovReady.hEvent = CreateEvent(NULL,TRUE,FALSE,NULL);
    WriteovReady.hEvent =CreateEvent(NULL,TRUE,FALSE,NULL);

    SECURITY_ATTRIBUTES sa;
    sa.nLength=sizeof(SECURITY_ATTRIBUTES);
    sa.lpSecurityDescriptor=NULL;
    sa.bInheritHandle=TRUE;

    DCB dcb;
    GetCommState(hComm, &dcb);
    dcb.fBinary = TRUE;
    dcb.fParity = TRUE;
    // 波特率  数据位  标志位 根据自己的设备在此做修改 
    dcb.BaudRate = CBR_9600;        // baud rate 9600
    dcb.ByteSize = 8;               
    dcb.Parity = NOPARITY;            
    dcb.StopBits = ONESTOPBIT;        

    if (!SetCommState(hComm, &dcb ))        return false;

    bOpenCom = true;
    return bOpenCom;
}

bool CommUtils::WriteCom(unsigned char *sendchar, int sendsize)
{
    if (!bOpenCom)    return false;

    DWORD    BytesSent;
    DWORD    resD;        

    PurgeComm(hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);

    BytesSent=0;
    BOOL hr = WriteFile(hComm,                            // Handle to COMM Port
                        sendchar,                        // Pointer to message buffer in calling finction
                        sendsize,                        // Length of message to send
                        &BytesSent,                        // Where to store the number of bytes sent
                        &WriteovReady);                    // Overlapped structure
    if(!hr)
    {
        if(GetLastError() != ERROR_IO_PENDING)
        {
            return false;
        }
        else
        {
            resD=WaitForSingleObject(WriteovReady.hEvent,INFINITE);
        }
        switch(resD)
        {
            case WAIT_OBJECT_0:
            {
                if(!GetOverlappedResult(hComm,&WriteovReady,&BytesSent,false))
                    return false;
                else
                    return true;

            }
            default:
                return false;
                break;
        }
    }
    return true;
}

void CommUtils::CloseCom()
{
    if (!bOpenCom)    return;

    CloseHandle(hComm);
    hComm=NULL;

    CloseHandle(ReadovReady.hEvent);
    CloseHandle(WriteovReady.hEvent );
    ReadovReady.hEvent =NULL;
    WriteovReady.hEvent =NULL;
}

bool CommUtils::ReadCom(unsigned char * ReceiveData, DWORD& ReceiveLength)
{
    if (!bOpenCom)    return false;
    if (ReadovReady.hEvent == NULL)    return false;

    ReceiveLength = 0;
    if (ReadFile(hComm, ReceiveData, 128, &ReceiveLength, &ReadovReady) == FALSE) 
    {
        if (GetLastError() != ERROR_IO_PENDING)    return false;
    }
    /*
    bResult = ReadFile(port->m_hComm,  // Handle to COMM port 
                &RXBuff,    // RX Buffer Pointer
                 1,     // Read one byte              
                 &BytesRead,   // Stores number of bytes read               
                 &port->m_ov);  // pointer to the m_ov structure                              
                 // deal with the error code */
    if(ReceiveLength == 0)    return false;
    ReceiveData[ReceiveLength] = 0;

    DWORD dwRead;
    DWORD dwRes = WaitForSingleObject(ReadovReady.hEvent, READ_TIMEOUT);
    switch(dwRes)
    {
        case WAIT_OBJECT_0:
            if (!GetOverlappedResult(hComm, &ReadovReady, &dwRead, FALSE))    return false;
            break;

        case WAIT_TIMEOUT:
            break;                

        default:
            break;
    }
    return true;
}

头文件CommUtils.h

#ifndef _CommUtils_H__
#define _CommUtils_H__

class CommUtils  
{
public:
    bool ReadCom(unsigned char * ReceiveData, DWORD& ReceiveLength);
    void CloseCom();
    bool WriteCom(unsigned char * sendchar,int sendsize);
    bool OpenCom(int Port);

    CommUtils();
    virtual ~CommUtils();
    int m_Port;
    char szCurPath[256];

private:
    OVERLAPPED ReadovReady, WriteovReady;
    HANDLE hComm;
    bool bOpenCom;
};

#endif

使用方法

1.将.cpp .h 文件拷贝到工程目录下；
2.右击项目—>添加—>现有项，将CommUtils.cpp CommUtils.h 添加进来
3.在自己的对话框类中包含该类的头文件

#include "CommUtils.h"

定义一个全局变量

CommUtils mCommUtils ;

接下来通过CommUtils 的实例mCommUtils 来操作串口
打开串口：

int Port;  //要操作的串口号
mCommUtils.OpenCom(Port);  //打开串口

读串口数据：

unsigned char COMdata[100]; //接收的数据
unsigned long len = 0;
mCommUtils.WriteCom(COMdata, len);

写数据：

unsigned char SendArr[6];
mCommUtils.WriteCom(SendArr,6)

最后关闭串口：

mCommUtils.CloseCom();

该类的析构函数中也调用了该函数，在对象被销毁时也会关掉串口。

最后

串口封装类的下载地址：CommUtils
只是想和大家分享经验，但是下载最少需要1个积分，大家可在自己的工程里右击—>添加—>类 ； 将代码复制过去，注意类名的变化，新建类的类名直接填CommUtils。

最后

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