C# COM拒绝访问

早上好不好 2015-07-15 04:58:30

C#程序读取传感器的数据，传感器由串口连接。现在问题是，我如果在运行程序前就连接好了传感器，然后打开串口就报出“COM3拒绝访问”，然后我只要把传感器拔了重插一下，再打开就可以了。或者在程序运行前不要连接传感器，等程序打开后再连接传感器，然后打开串口也没问题。
可是这样很麻烦，每次运行程序都要重新拔插一次。我用其他串口工具就不需要这样，一直连接的情况下，任何时候打开串口都能正常收到数据。所以不知道我的程序问题在哪？



 private void com_data_receive(object sender, SerialDataReceivedEventArgs e)

        {

            if (Closing) return;



            try

            {

                Listening = true;

                byte[] buf = new byte[24];

                receive_count += 1;

                COM.Read(buf, 0, 24);

                 COM.DiscardInBuffer();

                

                string receive_data = "";



                for (int i = 0; i < buf.Length; i++)

                {

                    receive_data += buf[i].ToString("X2");

                }

                string temperature = get_temperature(receive_data.Substring(36, 4)).ToString("0.00");

                string humility = get_humility(receive_data.Substring(40, 4)).ToString("0.00");

                string illumination = get_illumination(receive_data.Substring(44, 4)).ToString("0.00");



                this.Invoke((EventHandler)(delegate

                {

                    ListViewItem lvi = new ListViewItem(receive_count.ToString());

                    lvi.SubItems.Add(temperature);

                    lvi.SubItems.Add(humility);

                    lvi.SubItems.Add(illumination);

                    listView1.Items.Add(lvi);

                }));



        }



        private void button4_Click(object sender, EventArgs e)

        {

            if (comboBox1.SelectedItem != null && comboBox2.SelectedItem != null && comboBox3.SelectedItem != null && comboBox4.SelectedItem != null && comboBox5.SelectedItem != null)

            {



                if (COM.IsOpen)

                {

                    Closing = true;  

                    while (Listening) Application.DoEvents();  



                    COM.Close();

                    COM.Dispose();

                    Closing = false;

                }

                else

                {

                    com_setting();

                    try

                    {

                        COM.Open();

                        COM.DataReceived += new SerialDataReceivedEventHandler(com_data_receive);

                    }

                    catch (Exception ex)

                    {

                        COM.Close();

                        COM.Dispose();

                        COM = new SerialPort();

                        MessageBox.Show(ex.Message);

                    }



                }

                button4.Text = COM.IsOpen ? "关闭" : "开始";

            }

            else

            {

                MessageBox.Show("请设置参数");

            }

        }

              

        private void com_setting()

        {

              COM.PortName = comboBox1.Text;

              COM.NewLine = "\r\n";

              COM.RtsEnable = true;

              COM.BaudRate = int.Parse(comboBox2.Text);

              COM.DataBits = int.Parse(comboBox3.Text);

              switch (comboBox4.SelectedIndex)

              {

                  case 0: COM.Parity = Parity.None; break;

                  case 1: COM.Parity = Parity.Odd; break;

                  case 2: COM.Parity = Parity.Even; break;

                  case 3: COM.Parity = Parity.Mark; break;

                  case 4: COM.Parity = Parity.Space; break;

                  default: COM.Parity = Parity.None; break;

              }

              switch (comboBox5.SelectedIndex)

              {

                  case 0: COM.StopBits = StopBits.One; break;

                  case 1: COM.StopBits = StopBits.OnePointFive; break;

                  case 2: COM.StopBits = StopBits.Two; break;

                  default: COM.StopBits = StopBits.One; break;

              }



             

        }