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.NET SerialPort DataReceived problem

Posted on 2006-06-29
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1,809 Views
Last Modified: 2012-06-21
Hi,

I am using 2.0 and the SerialPort class to make and CSD data call and then parse the incoming data via DataReceived.

I am also using Portmon to analyse the actual data that is incoming through the port. So I can make sure I am getting everything correct.

I have been experiencing a few problems with picking up the data from the remote modem.

Randomly when I make a datacall every other packet sent from the remote modem, which can be seen in full via Portmon, is sent through as null via the DataReceived event. The event is being called but the data not included. The alternate packet is fine! - i.e data seen in portmon is sent via DataReceived.

To make the matter more harded to pin point, Somtimes when I connect EVERY packet is sent and rec totally fine, and there is no problem. This is what confuses me, why it works one time then not the other!!

Does anyone have a clue why this could be??

At first I thought it could be a result of signal strength on the remote modem, but the correct information is coming through ok as its shown in portmon.

Then i thought, and still do, is that the problem must be with my code somewhere.

I have tried reading from the port in bytes, char, readexisting, readline all with the same result.

I have also tried different encodings.

Hopefully I'm missing something somewhere.

Any help would be great., thanks in advance.

My current code;


         public bool OpenPort()
        {
            if (!mPort.IsOpen)
            {                
                try
                {
                    mPort.PortName = "COM1";
                    mPort.Handshake = Handshake.RequestToSendXOnXOff;
                    mPort.ReadTimeout = 50000;
                    mPort.Encoding = System.Text.Encoding.ASCII;
                    mPort.WriteTimeout = 50000;
                    mPort.Parity = Parity.None;
                    mPort.BaudRate = 9600;
                    mPort.StopBits = StopBits.One;
                    mPort.DataBits = 8;
                    mPort.DtrEnable = true;

                    mPort.Open();

                    return true;
                }
                catch
                {
                    // add relevant exceptions here
                    AddToLogFile("Can not open port");
                    return false;
                }
            }
            else
            {
                return true;
            }
        }

 // this is hooked up elsewhere      
 mPort.DataReceived += new SerialDataReceivedEventHandler(mPort_DataRecDownloadLog);

        public void mPort_DataRecDownloadLog(object sender, EventArgs e)
        {
                if (mPort.IsOpen)
                {
                   
                    int bnread = mPort.BytesToRead;
                    char[] a_char = new char[bnread];
                    int nread = 0;
                    nread = mPort.Read(a_char, 0, bnread);
                    string str = new string(a_char, 0, nread);
                   
                    ParseBuffer(str);
                 }
         }
0
Comment
Question by:jendy
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3 Comments
 
LVL 5

Accepted Solution

by:
t_itanium earned 500 total points
ID: 17015740
hi...
i have thiis problem once.. i dont know but i think that the data is sent some times in different parts...


i had once a weight scale that gives 5 digit wight with the unit at right ie:
11111 g

some times it works fine and some times it gives to inout  111 then 11 g

so it might be this is your problem ..i overcome this by using the system.threading

and use Thread.Sleep(time)

example:

  public void mPort_DataRecDownloadLog(object sender, EventArgs e)
        {
                if (mPort.IsOpen)
                {
                    Thread.Sleep(500);   //or 1000
                    int bnread = mPort.BytesToRead;
                    char[] a_char = new char[bnread];
                    int nread = 0;
                    nread = mPort.Read(a_char, 0, bnread);
                    string str = new string(a_char, 0, nread);
                   
                    ParseBuffer(str);
                 }
         }

0
 

Author Comment

by:jendy
ID: 17159491
Sorry, forgot about this one!

Thanks t_itanium, adding the wait did solve the problem.

It doesn't seem the mosst accurate method to me, but I haven't found anything else that works so I'll run with this for now.

Thanks again.

jendy
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