程序代码：

void CMyScomm2Dlg::OnOpen()
{
    // TODO: Add your control notification handler code here
        int iPort;
    CString strTmp,strSet;
    UpdateData();
    m_cmbCom.GetLBText(m_cmbCom.GetCurSel(),strTmp);////获取当前选项的索引及字符串，存入strTmp
    iPort = atoi(strTmp.Mid(3,(strTmp.GetLength()-3)));//com3,com254
   if(m_ctrlComm.GetPortOpen())
       m_ctrlComm.SetPortOpen(FALSE);
       m_ctrlComm.SetCommPort(iPort);//选择com1
    if( !m_ctrlComm.GetPortOpen())
    {
        m_ctrlComm.SetPortOpen(TRUE);//打开串口
        m_btnOpen.SetWindowText("关闭");
    }
    else
   
        AfxMessageBox("cannot open serial port");
   
    m_ctrlComm.SetSettings("9600,n,8,1"); //波特率9600，无校验，8个数据位，1个停止位
    m_ctrlComm.SetInputMode(1); //以二进制方式检到数据
    m_ctrlComm.SetRThreshold(1);
    //参数1表示每当串口接收缓冲区中有多于或等于1个字符时将引发一个接收数据的OnComm事件
    m_ctrlComm.SetInputLen(0);  //设置当前接收区数据长度为0
    m_ctrlComm.GetInput();//先预读缓冲区以清除残留数据
}