Avoid cross-thread errors: safely update UI elements from non-UI threads

When interacting with UI elements from non-UI threads (such as threads generated by receiving events from serial port data), thread safety issues must be handled to avoid cross-thread errors.

In C# code, the error "Cross-thread operation is invalid: Access control 'textBox1' from a thread other than the thread that created the control 'textBox1'" occurs because the UI thread owns the textBox1 control, and accessing it from another thread will Causes thread association conflicts.

To solve this problem, a scheduler must be used to allow appropriate threads (usually UI threads) to access UI elements. In this case, delegate and Invoke methods can be used to ensure thread-safe access:

delegate void SetTextCallback(string text);

private void SetText(string text)
{
  if (this.textBox1.InvokeRequired)
  { 
    SetTextCallback d = new SetTextCallback(SetText);
    this.Invoke(d, new object[] { text });
  }
  else
  {
    this.textBox1.Text = text;
  }
}

Now, in the serialPort1_DataReceived event handler:

private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
  txt  = serialPort1.ReadExisting().ToString();
  SetText(txt.ToString());
}

Using the SetText method, you can delegate tasks that update the textBox1 text attribute to the UI thread, ensuring safe and error-free access to UI elements from non-UI threads.