获取PC可用串口端口，并将其在combo box中显示

通常应用中，我会遇到需要用到多个串口的同时在一台PC上使用的情况，例如通过USB转串口等方式来硬件接入串口数目。

那么软件需要判断到底哪些串口号是可用的，才可以初始化相应的串口应用程序。

下面我们简单介绍一下，如何获取PC可用串口端口号，并将其显示在combo box控件中。

例程我们搜寻最多2个可用串口端口。

创建工程，在UI上添加如下控件：
因为我们需要用到两个串口，所以我们添加两个串口通信插件communications control(如果不需要操作串口，可不用).
添加按键事件处理函数 OnBnClickedStart

函数处理：

void CMicrohardTestDlg::OnBnClickedStart()
{
    // TODO: Add your control notification handler code here
    int i;
    CMscomm1 *pMsc = (CMscomm1*)this->GetDlgItem(IDC_MSCOMM1);
    CComboBox *pcombo = (CComboBox*)this->GetDlgItem(IDC_COMBO1);
    switch (g_w_Steps)
    {
    case 0://check serial port by openning produrce.
    {
               HANDLE hCom;
               CString strCOM;;
               m_Edit1_show = "";
               pMsc->put_Settings(_T("115200,n,8,1"));
               pcombo->ResetContent();//clear context
               for (i = 0; i < 256; i++)
               {
                   strCOM.Format(_T("COM%d"), i);
                   //open or Create a file or an I/O
                   hCom = CreateFile(_T("\\.\") + strCOM, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, 0);
                   if (hCom != INVALID_HANDLE_VALUE)
                   {
                       if (m_Edit1_show.IsEmpty())
                       {
                           pcombo->AddString(strCOM);
                           pcombo->SetCurSel(0);
                           pcombo = (CComboBox*)this->GetDlgItem(IDC_COMBO2);
                           m_Edit1_show = "PC Seral Ports Searching ...
First Port was found.
";
                       }
                       else
                       {
                           pcombo->AddString(strCOM);
                           pcombo->SetCurSel(0);
                           m_Edit1_show += "Second Port was found.
";
                       }
                   }
               }
               if (m_Edit1_show.IsEmpty())
               {
                   m_Edit1_show = "No PC Serial Port active.";
               }
               UpdateData(false);
               g_w_Steps++;
              break;
    }
    case 1:
    {
              break;
    }
    default:
        break;
    }
}

OnBnClickedStart

这里主要函数为

//open or Create a file or an I/O
 hCom = CreateFile(_T("\\.\") + strCOM, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, 0);

返回值不为 INVALID_HANDLE_VALUE 则说明串口端口可用。

到目前为止，我们活跃的串口已经打开了，但是我们并没有设置串口参数。那么我们需要先关有效的端口。更改后为：

void CMicrohardTestDlg::OnBnClickedStart()
{
    // TODO: Add your control notification handler code here
    int i,num;
    CString str,num_str;
    CMscomm1 *pMsc;
    CComboBox *pcombo;
    switch (g_w_Steps)
    {
    case 0://check serial port by openning produrce.
    {
               //point to combo box1
               pcombo = (CComboBox*)this->GetDlgItem(IDC_COMBO1);
               //clear context
               pcombo->ResetContent();
               num = 0;
               m_Edit1_show += _T("PC Serial Ports Searching ...
");
               for (i = 0; i < 256; i++)
               {
                   str.Format(_T("COM%d"), i);
                   //open or Create a file or an I/O
                   HANDLE hCom = CreateFile(_T("\\.\") + str, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, 0);
                   if (hCom != INVALID_HANDLE_VALUE)
                   {
                       num++;
                       pcombo->AddString(str);
                       pcombo->SetCurSel(0);
                       //point to combo box2
                       pcombo = (CComboBox*)this->GetDlgItem(IDC_COMBO2);
                       m_Edit1_show += str + _T(" was found.
");
                   }
                   CloseHandle(hCom);
                   if (num >= 2)break;
               }
               if (num >= 2)
               {
                   SetDlgItemText(IDC_BUTTON1, _T("OpenPorts"));
                   g_w_Steps++;
               }
               else
               {
                   str.Format(_T("%d Port are active, we need at least 2 Port Active.Please re-try.
"), num);
                   m_Edit1_show += str;
               }
               UpdateData(false);
              break;
    }
    case 1:
    {
              pMsc = (CMscomm1*)this->GetDlgItem(IDC_MSCOMM1);
              pcombo = (CComboBox*)this->GetDlgItem(IDC_COMBO1);
              //open 2 serial port
              for (i = 0; i < 2; i++)
              {
                  if (pMsc->get_PortOpen() == TRUE)
                  {
                      pMsc->put_PortOpen(FALSE);
                  }
                  //get combo box text--> str
                  pcombo->GetLBText(0, str);
                  //get str string num-->e.g "COM1235"==> num_str="1235"
                  num_str = str.Mid(3);
                  //get num from string num-->e.g "1235"==>num=1235
                  num = _ttoi(num_str);
                  pMsc->put_CommPort(num);
                  pMsc->put_Settings(_T("115200,n,8,1"));
                  pMsc->put_PortOpen(TRUE);
                  if (pMsc->get_PortOpen() == TRUE)
                  {
                      m_Edit1_show += str + _T(" was Opened Success. Configuration: 115200,n,8,1
");
                  }
                  pMsc = (CMscomm1*)this->GetDlgItem(IDC_MSCOMM2);
                  pcombo->EnableWindow(FALSE);
                  pcombo = (CComboBox*)this->GetDlgItem(IDC_COMBO2);
              }
              SetDlgItemText(IDC_BUTTON1, _T("Login"));
              UpdateData(false);
              g_w_Steps++;
              break;
    }
    case 2:
    {
              m_Edit1_show += _T("");
              break;
    }
    default:
        break;
    }
}

OnBnClickedStart

这里我们调用 CloseHandle(hCom); 来关闭相应的端口。

谢谢。

End.