How to buffer incoming serial Port Values. C#

Question

Hello could someone tell what is the best way to buffer incoming Values on serial port? Because I have the problem that some values are corrupted when written into a textBox. I already asked about that in the following question: Why do I get partly strange values from serial port in C# Someone told me it is because I don't buffer them. When I write the String that I get from serial port in to a text File, I get this:

Hope someone can help me.

I read the previous question and you don't seem to understand what the potential issue is. Say the serial port spits out "12.5g, 12.6g, 12.4g", but you read in each time more than 5 characters without knowing it, so you read in "12.5g, 1" on one read, then the next read reads in "2.6g, 12." or something similar. You writing to a text box is likely unrelated to your issue. — Quantic, Mar 22 '17 at 18:37
I think the problem is somewhere here: `int dataLength = _serialPort.BytesToRead; byte[] data = new byte[dataLength]; int nbrDataRead = _serialPort.Read(data, 0, dataLength); if (nbrDataRead == 0) return; string str = Encoding.UTF8.GetString(data);` — Sardar Agabejli, Mar 22 '17 at 18:42

itsme86 · Answer 1 · 2017-03-22T20:10:46.687

1

The best way to approach it is to use 'g' to mark the end of a string:

string leftOver = "";

// Read the data like you have

string str = leftOver + Encoding.UTF8.GetString(data);
int index = str.IndexOf('g');
if (index == -1)
{
    leftOver += str;
}
else
{
    leftOver = str.Substring(index + 1);
    str = str.Substring(0, index + 1);
}

edited Mar 22 '17 at 20:10

answered Mar 22 '17 at 18:53

itsme86

19,266
4
41
57

Sorry, this didn't help, because, there are NO semicolons. I just added them in the value list that you have a better overview. I think the problem is that my computer doesn't know when serial port is ready with one value. So that he knows that now the next value starts. But why? Or how to set this?! – Sardar Agabejli Mar 22 '17 at 19:09
1

That all depends on the device. – itsme86 Mar 22 '17 at 19:43
Do you think it has something to do with StopBits or Parity or Handshake? I tried lot of different configuration... nothing helped... Now I only read out the values consisting of 15 or 16 chars. Maybe this will be enough. Thank you anyway! – Sardar Agabejli Mar 22 '17 at 19:54
1

@SardarAgabejli You could always use 'g' as the terminator. I'll update my answer for you. – itsme86 Mar 22 '17 at 20:07
Thank you! I will try tomorrow and tell you if it works. – Sardar Agabejli Mar 22 '17 at 21:33
Setting "g" as terminator didn't helped.I think the Problem is that it doesn't know where an incoming value starts or ends. I mean on which bit or Byte. – Sardar Agabejli Mar 23 '17 at 13:21

score 1 · Accepted Answer · answered Mar 23 '17 at 15:02

OK I got it now!

I have to buffer the values coming via serial port from scale in a file at first. Don't really know why, but then the single values are in right form and can be read out without Problems.

private void SerialPortOnDataReceived(object sender, SerialDataReceivedEventArgs serialDataReceivedEventArgs)
{

    if (InvokeRequired)     //<-- Makes sure the function is invoked to work properly in the UI-Thread
        BeginInvoke(new Closure(() => { SerialPortOnDataReceived(sender, serialDataReceivedEventArgs); }));     //<-- Function invokes itself
    else
    {
        int dataLength = _serialPort.BytesToRead;                

        byte[] data = new byte[dataLength];
        int nbrDataRead = _serialPort.Read(data, 0, dataLength);
        if (nbrDataRead == 0)
            return;
        string str = Encoding.UTF8.GetString(data);


        //Buffer Values in a text file at first!
        File.AppendAllText("buffer1.txt", str);
        string strnew = File.ReadLines("buffer1.txt").Last();

        textBox5.Text = strnew;

My next problem is how to keep the buffer file in a appropriate size.

How to buffer incoming serial Port Values. C#

2 Answers2