如何在C＃中从SerialPort.Write修复System.IO.IOException？

Question

我有一个虚拟COM设备（从USB到UART），正在尝试使用C＃SerialPort命令。当我调用Write或WriteLine方法时，得到以下堆栈跟踪：

Exception (System.IO.IOException): The I/O operation has been aborted because of either a thread exit or an application request.
   at System.IO.Ports.InternalResources.WinIOError(Int32 errorCode, String str)
   at System.IO.Ports.SerialStream.EndWrite(IAsyncResult asyncResult)
   at System.IO.Ports.SerialStream.Write(Byte[] array, Int32 offset, Int32 count, Int32 timeout)
   at System.IO.Ports.SerialPort.Write(String text)

我已经通过设备文档以及通过PuTTY的成功通信确认了端口，波特率，奇偶校验和握手，所以问题肯定出在我的C＃代码上。

_serialPort = new SerialPort(commId, 9600, Parity.None, 8, StopBits.One)
{
    Handshake = Handshake.XOnXOff,
    ReadTimeout = 5000,
    WriteTimeout = 5000,
    NewLine = "\r", //added during debug
    DtrEnable = true, //added during debug
    RtsEnable = true //added during debug
};

_serialPort.DataReceived += new SerialDataReceivedEventHandler(SerialPort_DataReceived);

_serialPort.Open();

_serialPort.DiscardInBuffer(); //added during debug
_serialPort.DiscardOutBuffer(); //added during debug
_serialPort.Write("echo");
_serialPort.WriteLine("echo");