Question

I have an application that reads from a COM Port and then does something with the data that it receives. I am currently using a COM Port emulator (Since i don’t have the device available for me to use) but I am feeding it a sample of the data. The program seems to work perfectly fine if I open the COMPort before I start transmitting data. However, if I start transmitting before I open the COMPort, and then I open the port, the dataReceived event is never fired and I am never able to get any data. I have even tried to flush the INBuffer as soon as I open the port but am unable to read from it.

My code to open the port is this:

public void setupComPort(string baudRate, string dataBits, string stopBits, string parity, string portName)
    {
        if (comPort.IsOpen)
            comPort.Close();
        comPort.BaudRate = int.Parse(baudRate);
        comPort.DataBits = int.Parse(dataBits);
        comPort.StopBits = (StopBits)Enum.Parse(typeof(StopBits), stopBits);
        comPort.Parity = (Parity)Enum.Parse(typeof(Parity), parity);
        comPort.PortName = portName;
        // When data is recieved through the port, call this method
        comPort.DataReceived += new SerialDataReceivedEventHandler(port_DataReceived);
        try
        {
            // Open the port
            comPort.Open();
            //If there's data in buffer, discard so we can start receiving
            //comPort.DiscardInBuffer();
        }
        catch (Exception e)
        {
            MessageBox.Show(e.Message, "Error Opening Port", MessageBoxButton.OK, MessageBoxImage.Error);
        }
    }

Any help would be appreciated.

Answer 1

Its probably an issue with the emulator. I’ll guess the issue will go away when you have the actual hardware. The only other thing I can think to try is setting the ReceivedBytesThreshold to something other than the default (like 10 or something).