我试图用一个按钮打开和关闭我的COM端口。我可以打开并关闭它，但是在我想再次打开它之后，它捕获了第一个异常。
这是我的代码：
db.users.find( { "local": { email: "abc@hotmail.com" } } ).pretty()
首先，我的按钮说private void Button_Port_Open_Click(object sender, EventArgs e)
{
string Port_Name = ComboBox_Available_SerialPorts.SelectedItem.ToString();
int Baud_Rate = Convert.ToInt32(ComboBox_Standard_Baudrates.SelectedItem);
COMport = new SerialPort(Port_Name, Baud_Rate, Parity.None, 8, StopBits.One);
if (Button_Port_Open.Text == "Connect")
{
try
{
COMport.Open();
if (COMport.IsOpen == true)
{
Button_Port_Open.Text = "Disconnect";
#region EnableBoxes
GroupBox_Port_Commands.Enabled = true;
groupBox3.Enabled = true;
groupBox4.Enabled = true;
Button_Load_File.Enabled = false;
#endregion
TextBox_System_Log.Text = "***CONNECTED***" + Environment.NewLine + Port_Name + Environment.NewLine + Baud_Rate + " bps" + Environment.NewLine;
COMport.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
}
else
MessageBox.Show("Port could not be opened!");
}
#region Port exceptions
catch (UnauthorizedAccessException SerialException)
{
MessageBox.Show(SerialException.ToString());
COMport.Close();
}
catch (System.IO.IOException SerialException)
{
MessageBox.Show(SerialException.ToString());
COMport.Close();
}
catch (InvalidOperationException SerialException)
{
MessageBox.Show(SerialException.ToString());
COMport.Close();
}
catch
{
MessageBox.Show("ERROR in Opening Serial Port -- UnKnown ERROR");
COMport.Close();
}
#endregion
}
else
{
try
{
COMport.Close();
Button_Port_Open.Text = "Connect";
TextBox_System_Log.Text += "***DISCONNECTED***";
Thread.Sleep(5000);
//Button_Port_Close.Enabled = false;
}
catch (Exception error)
{
MessageBox.Show(error.ToString());
}
}
}
，然后按它变成Connect（因此，if语句确定程序是否需要打开或关闭端口）。