How to use SerialPort in .Net by using DataReceived event?

Question

I know the DataReceived event is fired on a background thread. How do I tell the GUI thread to show the data in the event handler?

Answer 1

You can use the IsInvokeRequired and BeginInvoke methods on your form to switch control back to the UI thread.

In some cases, I've also used a timer to watch for changes in some shared data structure like a list of messages. But that works best when you've got a pretty steady stream of messages coming from some background thread.

Answer 2

This code assumes you have already added a form-level SerialPort object with the port_DataReceived method attached to its DataReceived event, and that you have a label named label1 on your form.

I'm not 100% certain about the code that converts the bytes available in the port to a string, as I have not run this with a live serial port collecting data. But this code will allow you to display the received data regardless of whether the event is on a different thread or not.

void port_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    SerialPort port = (SerialPort)sender;
    byte[] buffer = new byte[port.BytesToRead];
    port.Read(buffer, 0, buffer.Length);
    string data = UnicodeEncoding.ASCII.GetString(buffer);
    if (label1.InvokeRequired)
    {
        Invoke(new EventHandler(DisplayData), data, EventArgs.Empty);
    }
    else
    {
        DisplayData(data, EventArgs.Empty);
    }
}

private void DisplayData(object sender, EventArgs e)
{
    string data = (string)sender;
    label1.Text = data;
}