old data appearing in serial port

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Hi.,

I have written a code to read data from the serial continuously. But when running the code for long duration like 3-4 hours serial data receiving is not in corresponding to the data that is sent by the sender. If the same code is run for few min. it does not show any problem of that sort i.e, what the sender sends is immediately reflected at the serialport receive. please give any solution if available that does not make lose of data. here is the code for serial data receive

<pre lang="c#">th = new System.Threading.Thread(serialPort1_DataReceived);
                        th.IsBackground = true;
                        th.Start();

in serialPort1_DataReceived method

C#

RxString += serialPort1.ReadLine();
               DisplayText(RxString);

in "DisplayText" method I do some operations to split "rxstring" and display it in a text box.

Also I need to know why this problem does not occurs when using hyper-terminal like "putty"

thanks in advance

Posted 15-May-14 21:30pm

Sachinsnagaraj

Updated 15-May-14 21:35pm

v2

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CPallini 16-May-14 3:57am

Probably you just handle incorrectly the received data. However, without actually seeing your code there's a little we can do to help you.

Sachinsnagaraj 16-May-14 5:58am

i putting my code to displaytext 
 
try 
{ 
if (this.chart1.InvokeRequired)// i am using some charts to plot some //points on graph 
{ 
SetTextCallback x = new SetTextCallback(this.DisplayText); 
this.Invoke(x, new object[] { rxt }); 
} 
else 
{ 
if (status) 
{ 
string deviceid = string.Empty; 
string devicename = string.Empty; 
string power = string.Empty; 
 
TextBox.CheckForIllegalCrossThreadCalls = false; 
//RxString = RxString.Remove(RxString.Length - 1, 1); 
string[] cntstring = rxt.ToString().Split(':'); 
if (cntstring.Length == 2) 
{ 
deviceid = cntstring[0]; 
power = cntstring[1].Remove(cntstring[1].Length-1,1); 
devicename = deviceid; 
dataflag = true; 
} 
 
if (deviceid != "" && !(deviceslist.Contains(deviceid)) && deviceid.Length == 5) 
{ 
try 
{ 
deviceslist.Add(deviceid); 
devicename = deviceid; 
if (!deviceidlist.Contains(deviceid)) 
{ 
deviceidlist.Add(deviceid); 
} 
} 
catch 
{ 
 
} 
} 
 
 
double po = 0; 
try 
{ 
po = double.Parse(power); 
} 
catch 
{ 
po = 0; 
} 
 
//Checklog(po.ToString(), deviceid); 
if (deviceslist.Contains(deviceid) && po >= threshold && po <= 5000) 
{ 
if (dataflag == true) 
{ 
try 
{ 
devicename = getdeviceName(deviceid); 
if (devicename == "" || devicename == null) 
{ 
try 
{ 
devicename = deviceid; 
// addtochartseries(deviceslist.IndexOf(deviceid), "device : " + devicename); 
 
} 
catch 
{ 
 
} 
} 
 
} 
catch 
{ 
devicename = deviceid; 
} 
if (g1.Visible

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OriginalGriff · Answer 1 · 2014-05-15T21:40:00

Without the code fro teh "DisplayText" method, we have to guess - but I'd bet it has to do with the "+=" part:

C#

RxString += serialPort1.ReadLine();

Given that the DataRecieved event is handled on a non-UI thread, if your DisplayText method is using controls (as I would assume it does or you'd get cross threading errors) then there is a good chance that the UI thread is also modifying RxString at the same time - this is dangerous and can lead to all sorts of intermittent weird problems.

I would suggest that at a very minimum, you need to look at making all your code thread safe.