The I/O operation has been aborted because of either a thread exit or an application request

See more:

C#

serial-port

The motto for the project is to extablish a test setup to check data send & receive with different serial port settings such as baud rate, data bits, parity etc. When the serial port baud rate is changed and executed, the above error occurs during reading/writing data. Some times the error occurs when accessing serial port properties.
Sample application is created with 2 serial port objects, assume com1 & com7. Data is sent from Com1 to Com7. I have a thread that recieves the data in com7 and sends it back to Com1. Using another thread, data from com1 is read and write to file. Code is attached below.

private void Form2_Load(object sender, EventArgs e)
{
  sp.BaudRate = 9600;
  sp.DataBits = 8;
  sp.StopBits = StopBits.One;
  sp.Handshake = Handshake.None;
  sp.Parity = Parity.None;
  sp.PortName = "COM7";
  sp.Open();
  sp1.BaudRate = 9600;
  sp1.DataBits = 8;
  sp1.StopBits = StopBits.One;
  sp1.Handshake = Handshake.None;
  sp1.Parity = Parity.None;
  sp1.PortName = "COM1";
  sp1.Open();

  rxThread = new Thread(new ThreadStart(ReceiveBytes));
  rxThread.SetApartmentState(ApartmentState.STA);
  rxThread.Name = "Serial Receive Message Thread";
  rxThread.Start();
  rxThread1 = new Thread(new ThreadStart(ReceiveBytes1));
  rxThread1.SetApartmentState(ApartmentState.STA);
  rxThread1.Name = "Serial Receive Message Thread";
  rxThread1.Start();
  _SyncObj = new object();
}
private void ReceiveBytes1()
{
  try
  {
    sw1 = new StreamWriter("C:\\sample1.txt", true);
    while (true)
    {
      if (bAbort)
        break;
      if (sp != null)
      {
        while (sp.IsOpen && sp.BytesToRead > 0 && sp.BreakState == false)
        {
          if (sp.IsOpen)
          {
            String res = sp.ReadExisting();
            sb.Append(res);
            //sw1.Write(res);
          }
        }
      }
    }
  }
  catch (Exception ex)
  {
    string r = ex.Message;
  }
}
private void ReceiveBytes()
{
  try
  {
    while (true)
    {
      if (bAbort)
        break;
      if (sp1 != null)
      {
        while (sp1.IsOpen && sp1.BytesToRead > 0 && sp1.BreakState == false) // Read Bytes, if available from port
        {
          if (sp1.IsOpen)
          {
            //string res = sp1.ReadExisting();
            //lock (_SyncObj)
            //{
            int res = sp1.ReadByte();
            if (sp1.BreakState == false)
              sp1.Write(new Byte[] { (Byte)res }, 0, 1);
            //}
          }
        }
      }
    }
  }
  catch (Exception ex)
  {
    string r = ex.Message;
  }
}
public void ClearSerialPort()
{
  try
  {
    sp.BreakState = true;
    Thread.Sleep(2400);
    while (sp.BytesToRead > 0)
      sp.DiscardInBuffer();
    while (sp.BytesToWrite > 0)
      sp.DiscardOutBuffer();
  }
  catch (Exception e)
  {
    string err = e.Message;
  }
}
public void ClearSerialPort1()
{
  try
  {
    sp1.BreakState = true;
    Thread.Sleep(2400);
    while (sp1.BytesToRead > 0)
      sp1.DiscardInBuffer();
    while (sp1.BytesToWrite > 0)
      sp1.DiscardOutBuffer();
  }
  catch (Exception e)
  {
    string err = e.Message;
  }
}
private void button1_Click(object sender, EventArgs e)
{
  for (int i = 1; i < 6; i++)
  {
    // Attempt 1
    String hexData = GetHexStringFromFile("C:\\Documents and Settings\\ravikr0\\Desktop\\test\\testfiles_1019\\test_1Kb.txt");
    Char[] data = GetCharArrayfromString(hexData);
    SendData(data);
    ClearSerialPort();
    ClearSerialPort1();
    sp1.BaudRate = 1200;
    sp.BaudRate = 1200;
    sp.BreakState = false;
    sp1.BreakState = false;
    // Attempt 2
    hexData = "12345678901234567890";
    data = GetCharArrayfromString(hexData);
    SendData(data);
    ClearSerialPort();
    ClearSerialPort1();
    sp1.BaudRate = 2400;
    sp.BaudRate = 2400;
    sp.BreakState = false;
    sp1.BreakState = false;
    // Attempt 3
    hexData = GetHexStringFromFile("C:\\Documents and Settings\\ravikr0\\Desktop\\test\\testfiles_1019\\test_1Kb.txt");
    data = GetCharArrayfromString(hexData);
    SendData(data);
    ClearSerialPort();
    ClearSerialPort1();
    sp1.BaudRate = 4800;
    sp.BaudRate = 4800;
    sp.BreakState = false;
    sp1.BreakState = false;
    // Attempt 4
    hexData = GetHexStringFromFile("C:\\Documents and Settings\\ravikr0\\Desktop\\test\\testfiles_1019\\test_1Kb.txt");
    data = GetCharArrayfromString(hexData);
    SendData(data);
    ClearSerialPort();
    ClearSerialPort1();
    sp1.BaudRate = 9600;
    sp.BaudRate = 9600;
    sp.BreakState = false;
    sp1.BreakState = false;
    // Attempt 2
    hexData = GetHexStringFromFile("C:\\Documents and Settings\\ravikr0\\Desktop\\test\\testfiles_1019\\test_1Kb.txt");
    data = GetCharArrayfromString(hexData);
    SendData(data);
  }
}
private void Form2_FormClosed(object sender, FormClosedEventArgs e)
{
  bAbort = true;
  if (rxThread != null)
    rxThread.Join(1000);
  if (sw != null)
    sw.Close();
  if (rxThread1 != null)
    rxThread1.Join(1000);
  if (sw1 != null)
    sw1.Close();
}
public void SendData(Char[] data)
{
  try
  {
    sp.Write(data, 0, data.GetLength(0));
  }
  catch (Exception ex)
  {
    String err = ex.Message;
  }
}

Please provide me suggestions on how to overcome from this error.