我有一个应用程序，它通过串行端口读取 XBee 帧并在 Richtextbox 中显示该帧。它还在图表中显示 2 个模拟通道（温度读数）并实时更新。
我遇到的问题是应用程序读取串行端口的速度比输入字节的速度快，所以我添加了这一行：
while (comPort.BytesToRead < (inLength + 4)) Thread.Sleep(10);
这解决了这个问题，但现在我无法关闭串行端口或退出应用程序而不会收到以下消息：“System.dll 中发生‘System.InvalidOperationException’类型的未处理异常附加信息：端口已关闭。”
我怀疑这是一个多线程问题，但我该如何解决呢？我在类似的帖子中看到使用 BeginInvoke 而不是 Invoke 应该可以解决问题，但我已经在使用它了。
这是代码：
namespace SerialTest
{
public partial class frmMain : Form
{
delegate void SetTextCallback(string text);
delegate void SetChartCallback(double a, double b);
string inRawFrame = String.Empty;
double temp1 = 0;
double temp2 = 0;
public frmMain()
{
InitializeComponent();
}
private void btnGetSerialPorts_Click(object sender, EventArgs e)
{
if(btnGetSerialPorts.Text == "Open")
{
btnGetSerialPorts.Text = "Close";
comPort.PortName = Convert.ToString(cboPorts.Text);
comPort.BaudRate = Convert.ToInt32(cboBaudRate.Text);
comPort.ReadTimeout = 4000;
comPort.WriteTimeout = 6000;
if (!comPort.IsOpen)
{
try
{
comPort.Open();
cboPorts.Enabled = false;
cboBaudRate.Enabled = false;
}
catch(UnauthorizedAccessException ex)
{
MessageBox.Show(ex.Message);
}
}
}
else if (btnGetSerialPorts.Text == "Close")
{
btnGetSerialPorts.Text = "Open";
comPort.Close();
cboPorts.Enabled = true;
cboBaudRate.Enabled = true;
}
}
private void Form1_Load(object sender, EventArgs e)
{
string[] arrayComPortsNames = null;
int index = 0;
string comPortName = null;
arrayComPortsNames = SerialPort.GetPortNames();
Array.Sort(arrayComPortsNames);
while (!((arrayComPortsNames[index] == comPortName) || (index == arrayComPortsNames.GetUpperBound(0))))
{
cboPorts.Items.Add(arrayComPortsNames[index]);
index++;
}
comPortName = arrayComPortsNames[0];
cboPorts.Text = comPortName;
cboBaudRate.Items.Add(9600);
cboBaudRate.Items.Add(14400);
cboBaudRate.Items.Add(19200);
cboBaudRate.Items.Add(38400);
cboBaudRate.Items.Add(57600);
cboBaudRate.Items.Add(115200);
cboBaudRate.Items.ToString();
cboBaudRate.Text = cboBaudRate.Items[5].ToString();
}
private void comPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
byte[] incByte = new byte[3];
int length = 0;
if(comPort.BytesToRead > 3)
{
comPort.Read(incByte, 0, 3);
if (incByte[0] == 0x7E)
{
length = (incByte[1] << 8) + incByte[2];
byte[] buffer = new byte[length+4];
buffer[0] = incByte[0];
buffer[1] = incByte[1];
buffer[2] = incByte[2];
ReadFrame(buffer, length, DateTime.Now);
temp1 = ReadTemp(buffer, 1);
temp2 = ReadTemp(buffer, 2);
DisplayFrame();
UpdateChart();
}
}
}
private void ReadFrame(byte[] inBuffer, int inLength, DateTime time)
{
while (comPort.BytesToRead < (inLength + 4)) Thread.Sleep(10);
comPort.Read(inBuffer, 3, (inBuffer.Length - 3));
inRawFrame = time + " " + BitConverter.ToString(inBuffer).Replace("-", " ");
}
private void DisplayFrame()
{
if (rtbIncomingData.InvokeRequired)
{
rtbIncomingData.BeginInvoke(new SetTextCallback(SetText), new object[] { inRawFrame });
}
else
{
SetText(inRawFrame);
}
}
private void SetText(string text)
{
this.rtbIncomingData.AppendText(text + Environment.NewLine);
}
private double ReadTemp(byte[] data, int channel)
{
if(data[3] == 0x92)
{
if(channel == 1)
{
return ((((data[19] << 8) + data[20]) * 1.2 / 1023) - 0.5) * 100.0;
}
else
{
return ((((data[21] << 8) + data[22]) * 1.2 / 1023) - 0.5) * 100.0;
}
}
else
return 100;
}
private void UpdateChart()
{
if (chart1.InvokeRequired)
chart1.BeginInvoke(new SetChartCallback(SetChart), new object[] { temp1, temp2 });
else
SetChart(temp1, temp2);
}
private void SetChart(double val1, double val2)
{
chart1.ChartAreas["ChartArea1"].AxisX.LabelStyle.Format = "HH:mm:ss";
chart1.ChartAreas["ChartArea1"].AxisX.MajorGrid.LineColor = Color.LightGray;
chart1.ChartAreas["ChartArea1"].AxisY.MajorGrid.LineColor = Color.LightGray;
chart1.ChartAreas["ChartArea1"].AxisX.LabelStyle.Font = new Font("Consolas", 8);
chart1.ChartAreas["ChartArea1"].AxisY.LabelStyle.Font = new Font("Consolas", 8);
chart1.ChartAreas["ChartArea1"].AxisY.Maximum = 30;
chart1.ChartAreas["ChartArea1"].AxisY.Minimum = 10;
chart1.ChartAreas["ChartArea1"].AxisY.Interval = 1;
chart1.Series[0].Name = "Temp 1";
chart1.Series[1].Name = "Temp 2";
chart1.Series[0].ChartType = System.Windows.Forms.DataVisualization.Charting.SeriesChartType.Line;
chart1.Series[0].MarkerStyle = System.Windows.Forms.DataVisualization.Charting.MarkerStyle.Diamond;
chart1.Series[0].XValueType = System.Windows.Forms.DataVisualization.Charting.ChartValueType.DateTime;
chart1.Series[1].ChartType = System.Windows.Forms.DataVisualization.Charting.SeriesChartType.Line;
chart1.Series[1].MarkerStyle = System.Windows.Forms.DataVisualization.Charting.MarkerStyle.Diamond;
chart1.Series[1].XValueType = System.Windows.Forms.DataVisualization.Charting.ChartValueType.DateTime;
chart1.Series[0].Points.AddXY(DateTime.Now, val1);
chart1.Series[1].Points.AddXY(DateTime.Now, val2);
}
}
}