C# and RS485/USB receiving extraneous characters - c#-4.0

Question

In my project with six laser particle counters, when I send the commands, always return extraneous characters. And sometimes the string received in the form this incomplete. Below is a snippet of code: Who know fix this?
/// <summary>
/// Class to keep track of string and color for lines in output window.
/// </summary>
private class Line
{
public string Str;
public Color ForeColor;
public Line(string str, Color color)
{
Str = str;
ForeColor = color;
}
}
ArrayList lines = new ArrayList();
Font origFont;
Font monoFont;
public Form1()
{
InitializeComponent();
outputList_Initialize();
Settings.Read();
TopMost = Settings.Option.StayOnTop;
CommPort com = CommPort.Instance;
com.StatusChanged += OnStatusChanged;
com.DataReceived += OnDataReceived;
com.Open();
}
#region Event handling - data received and status changed
/// <summary>
/// Prepare a string for output by converting non-printable characters.
/// </summary>
/// <param name="StringIn">input string to prepare.</param>
/// <returns>output string.</returns>
private String PrepareData(String StringIn)
{
// The names of the first 32 characters
string[] charNames = {
// "NUL", "SOH", "STX", "ETX", "EOT",
//"ENQ", "ACK", "BEL", "BS", "TAB", "LF", "VT", "FF", "CR", "SO", "SI",
//"DLE", "DC1", "DC2", "DC3", "DC4", "NAK", "SYN", "ETB", "CAN", "EM", "SUB",
//"ESC", "FS", "GS", "RS", "US", "Space"
};
string StringOut = "";
foreach (char c in StringIn)
{
if (Settings.Option.HexOutput)
{
StringOut = StringOut + String.Format("{0:X2} ", (int)c);
}
else if (c < 32 && c != 9)
{
StringOut = StringOut + "";// +"<"+charNames[c]+">";
//Uglier "Termite" style
//StringOut = StringOut + String.Format("[{0:X2}]", (int)c);
}
else
{
StringOut = StringOut + c;
}
}
return StringOut;
}
/// <summary>
/// Partial line for AddData().
/// </summary>
private Line partialLine = null;
/// <summary>
/// Add data to the output.
/// </summary>
/// <param name="StringIn"></param>
/// <returns></returns>
private Line AddData(String StringIn)
{
String StringOut = PrepareData(StringIn);
// if we have a partial line, add to it.
if (partialLine != null)
{
// tack it on
partialLine.Str = partialLine.Str + StringOut;
outputList_Update(partialLine);
return partialLine;
}
return outputList_Add(StringOut, receivedColor);
}
// delegate used for Invoke
internal delegate void StringDelegate(string data);
/// <summary>
/// Handle data received event from serial port.
/// </summary>
/// <param name="data">incoming data</param>
public void OnDataReceived(string dataIn)
{
//Handle multi-threading
if (InvokeRequired)
{
Invoke(new StringDelegate(OnDataReceived), new object[] { dataIn });
return;
}
// pause scrolling to speed up output of multiple lines
bool saveScrolling = scrolling;
scrolling = false;
// if we detect a line terminator, add line to output
int index;
while (dataIn.Length > 0 &&
((index = dataIn.IndexOf("\r")) != -1 ||
(index = dataIn.IndexOf("\n")) != -1))
{
String StringIn = dataIn.Substring(0, index);
dataIn = dataIn.Remove(0, index + 1);
logFile_writeLine(AddData(StringIn).Str);
logFile_writeLine1(AddData(StringIn).Str);
partialLine = null; // terminate partial line
}
// if we have data remaining, add a partial line
if (dataIn.Length > 0)
{
partialLine = AddData(dataIn);
}
// restore scrolling
scrolling = saveScrolling;
outputList_Scroll();
listBox1_Scroll();
}
/// <summary>
/// Update the connection status
/// </summary>
public void OnStatusChanged(string status)
{
//Handle multi-threading
if (InvokeRequired)
{
Invoke(new StringDelegate(OnStatusChanged), new object[] { status });
return;
}
textBox1.Text = status;
}
#endregion

Answer 1

Could it be bit (or byte) stuffing ?