Default serial port settings for VirtualCOM over USB (lpc1768)

void USBCommTask(void const *argument) {	
	int ret = -1;
	char strMessage[50];
	
	// osDelay sometimes skipped depending depending on allocated stack size
	ret = USBD_Initialize(0U);
	osDelay(6000);
	sprintf(strMessage, "USBD_Initialize returned %d", ret);
	PrintDbgMessage(strMessage, 6000);
	
	memset(&strMessage[0], 0, sizeof(strMessage));
	
	ret = USBD_Connect(0U);
	osDelay(6000);
	sprintf(strMessage, "USBD_Connect returned %d", ret);
	PrintDbgMessage(strMessage, 6000);
  while(!USBD_Configured  (0U));	 
	PrintDbgMessage("USBD configured successfully!", 6000);	
	
	// Read from the USB port
	// http://www.keil.com/support/man/docs/rlarm/rlarm_usb_create_cdc_acm.htm
	// https://community.arm.com/developer/tools-software/tools/f/keil-forum/32812/usbd_cdc_acm_datasend-no-sending
	// http://wirelessblue.blogspot.com/2017/05/serial-port-over-usb-project.html
	while (1) {
		PrintDbgMessage("Writing to USB ... ", 6000);
		strcpy(strMessage, "ab");
		ret = USBD_CDC_ACM_WriteData(0U, (const uint8_t *)strMessage, strlen(strMessage));
		if (ret > 0) {
			sprintf(strMessage, "Wrote %d bytes of data to USB!", ret);
			PrintDbgMessage(strMessage, 6000);
		} else {
			sprintf(strMessage, "USBD_CDC_ACM_WriteData returned %d", ret);
			PrintDbgMessage(strMessage, 6000);
		}
		PrintDbgMessage("Wrote to USB!", 6000);
  }
}

            SerialPort serialPort = null;
            try
            {
                // Create a new SerialPort object with default settings.
                serialPort = new SerialPort();
                // Allow the user to set the appropriate properties.
                serialPort.PortName = "COM6";
                serialPort.BaudRate = 9600;
                // Use 115200 in all cases 
                // serialPort.BaudRate = 115200;
                serialPort.Parity = Parity.None;
                serialPort.DataBits = 8;
                serialPort.StopBits = StopBits.One;
                serialPort.Handshake = Handshake.None;
                // Set the read/write timeouts
                serialPort.ReadTimeout = 500;
                serialPort.WriteTimeout = 500;
        
                serialPort.Open();
                serialPort.DataReceived += WaitForHB01Ack;


                Console.WriteLine("Port opened successfully!");
            }
            catch (SystemException se)
            {
                Console.WriteLine("Exception opening port: " + se.ToString());
            }

Exception opening port: System.IO.IOException: Ein an das System angeschlossenes Gerät funktioniert nicht.
   at System.IO.Ports.SerialStream.InitializeDCB(Int32 baudRate, Parity parity, Int32 dataBits, StopBits stopBits, Boolean discardNull)
   at System.IO.Ports.SerialStream..ctor(String portName, Int32 baudRate, Parity parity, Int32 dataBits, StopBits stopBits, Int32 readTimeout, Int32 writeTimeout, Handshake handshake, Boolean dtrEnable, Boolean rtsEnable, Boolean discardNull, Byte parityReplace)
   at System.IO.Ports.SerialPort.Open()