多线程 C# serialPort1_DataReceived 事件不触发

Question

I read/write data to serial port and I want to see reading on listbox right away. I created a new thread to send command to serial port. I keep the main thread empty, so, it can update the UI and also serial port event handler wont be interrupted with something else.(I am not sure is it right approach?)

The following code works with while (.dataRecieved) { Thread;Sleep(4000); } while (.dataRecieved) { Thread;Sleep(4000); } but does not works with while (.dataRecieved) { Thread;Sleep(100); } while (.dataRecieved) { Thread;Sleep(100); } . The problem is if I use 100ms sleep, serial port event handler fire only once and then program stops.(If I debug with breakpoint 100ms works because I create additional time when stepping into the code.) If I wait 4000ms the program works, Also. I check the time between sending data and receiving data from serial port is 200ms, So. 100ms is reasonable.

Here is the code:

public bool dataRecieved = false;

public Form1()
        {
            InitializeComponent();
        }

        public void AppendTextBox(string value)
        {
            this.Invoke((MethodInvoker)delegate { richTextBox1.Text += value + "\n";});
        }

private void button1_Click(object sender, EventArgs e)
        {
            serialPort1.Open();
            Thread testThread = new Thread(() => sendThread());
            testThread.Start();
        }

public void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            data = serialPort1.ReadLine();
            dataRecieved = true;
        }

public void sendThread()
        {
            for(int i = 0; i<10; i++) 
            {
              serialPort1.WriteLine("AT" + i);
              // Following line creates odd situation:
              // if Thread.Sleep(100), I receive only first data, then program stops(serial port handler doesnt fire!).
              // if Thread.Sleep(4000), I receive all data, successfuly works.
              // But I do not want to wait 4000ms, because I receive answer from device in 200ms.
              while (!dataRecieved) { Thread.Sleep(100); }
              AppendTextBox("Received" + "AT" + i);
              dataRecieved = false;
            }
        } 

Where I am wrong? Can you please provide a solution?

Answer 1

I even didn't use a new Thead for write and read on SerialPort. You just need use update control in Invoke() is ok. Below is my update on richTextBox. You can change form richTextBox to your listbox.

 public void update_RichTextBox(string message)
        {
            Invoke(new System.Action(() =>
            {
                txtReceivedData.Text += message;
                txtReceivedData.Refresh();
                txtReceivedData.SelectionStart = txtReceivedData.Text.Length;
                txtReceivedData.ScrollToCaret();
            }));
            
        }

and the way to use above void:

if (ComPort.IsOpen)
  {
                ComPort.Write(_inputdata + "\r");
                Form1._Form1.update_RichTextBox(_inputdata + "\r");
                string _receviedData = ComPort.ReadExisting();
                Form1._Form1.update_RichTextBox(respond);
                ComPort.DiscardInBuffer();//delete all data in device's received buffer
                ComPort.DiscardOutBuffer();// delete all data in transmit buffer
  }
else
            {
                MessageBox.Show("haven't yet open COM port");
                return "FLASE";
            }

Answer 2

I use something I call "Cross Thread Linker"

#region Cross Thread Linker
public bool ControlInvokeRequired(Control c, Action a)
{
    if (c.InvokeRequired) c.Invoke(new MethodInvoker(delegate { a(); }));
    else return false;
    return true;
}

void Update_RichTextBox(RichTextBox rtb, string Text)
{
    if (ControlInvokeRequired(rtb, () => Update_RichTextBox(rtb, Text))) return;
    rtb.AppendText(Text + Environment.NewLine);
}

#endregion

Then:

Update_RichTextBox(richTextBox1, "Text to append");