打开/关闭串口

　　　　　　　　　 //关闭串口
                if (((MainForm)this.Owner).serialPort_GPS != null)
                {
                    try
                    {
                        if (((MainForm)this.Owner).serialPort_GPS.IsOpen)
                        {
                            ((MainForm)this.Owner).serialPort_GPS.Close();
                            ((MainForm)this.Owner).serialPort_GPS = null;
                        }
                    }
                    catch
                    {
                        checkBox_GPS_Enabled.Checked = true;

                        Form_MessageBox FMB = new Form_MessageBox();
                        FMB.m_strInfo = "关闭GPS串口失败！\r\n请检查是否被占用！";
                        FMB.ShowDialog();
                    }
                }                

                //新建并打开串口
　　　　　　　　　 if (((MainForm)this.Owner).serialPort_GPS == null)
                {
                    try
                    {
                        ((MainForm)this.Owner).serialPort_GPS = new SerialPort(
                            comboBox_GPS_PortName.Text,
                            Convert.ToInt32(comboBox_GPS_BaudRate.Text),
                            (Parity)comboBox_GPS_Parity.SelectedIndex,
                            Convert.ToInt32(comboBox_GPS_DataBits.Text),
                            (StopBits)comboBox_GPS_StopBits.SelectedIndex);
                        //打开GPS串口
						((MainForm)this.Owner).serialPort_GPS.Open();
                        //设置频率?
						((MainForm)this.Owner).SetGSVFreq();
						//设置GPS模式
                        ((MainForm)this.Owner).SetGPSOutMode();


                        comboBox_GPS_BaudRate.Enabled = false;
                        comboBox_GPS_DataBits.Enabled = false;
                        comboBox_GPS_Parity.Enabled = false;
                        comboBox_GPS_PortName.Enabled = false;
                        comboBox_GPS_StopBits.Enabled = false;
                        textBox_GPS_TestData.Enabled = false;
                        BTN_GPS_PortTest.Enabled = false;
                        BTN_GPS_BackToDefault.Enabled = false;

                    }
                    catch
                    {
                        ((MainForm)this.Owner).serialPort_GPS = null;
                        checkBox_GPS_Enabled.Checked = false;

                        Form_MessageBox FMB = new Form_MessageBox();
                        FMB.m_strInfo = "打开GPS串口失败！\r\n请检查串口配置！\r\n请检查串口是否被占用！";
                        FMB.ShowDialog();
                    }
                }