c# Serial comms Read data and add to an array

Question

I have got myself a little lost with this Windows forms application:(

I have a stream of data arriving at a serial port in the format of \W0987654321\L555666444\W3456789900\L9842429009 and so it repeats with different values for \L and \W

I need to split out the \W and \L values and add them to an array which is to expand as needed. and then plot them on a graph in real time.

Where i'm lost is how to read the port to get each complete value once it has arrived and not truncate it. I just can't get my brain around this so any help would be great...

I open the port thus:

port.PortName = "COM9";
port.BaudRate = 38400;
port.DataBits = 8;
port.Parity = Parity.None;
port.StopBits = StopBits.One;
port.DtrEnable = false;
port.Handshake = Handshake.None;

port.DataReceived += new System.IO.Ports.SerialDataReceivedEventHandler(port_DataReceived_1);
port.Open();

textBox1.Clear();
port.DiscardInBuffer();
port.DtrEnable = true;

Currently i have it all writing to a text box:

private void port_DataReceived_1(object sender, SerialDataReceivedEventArgs e)
{
    InputData = port.ReadExisting();

    if (InputData != String.Empty)
    {
        this.BeginInvoke(new SetTextCallback(SetText), new object[] { InputData });
    }
}

private void SetText(string text)
{
    this.textBox1.AppendText(text);
}

which shows all the data OK

Are the L and W value lengths consistent? If they are, just split on length, if not, you will only know when a complete value has been received when you see the start of the next one - meaning that you can never be fully 'up-to-date'. As long as it's OK for your application to be potentially one value behind, just check and delimit whenever you encounter a '/' — paul
– paul, Commented Jan 23, 2015 at 11:58
@Leppie I added that the first few characters can be corrupt when i open the port, it hasn't helped. — RTFS
– RTFS, Commented Jan 23, 2015 at 12:03
@Paul no the length can change, how do i know when the buffer contains \W1234567890\ so i can read only the data without losing the next part? — RTFS
– RTFS, Commented Jan 23, 2015 at 12:04
Do not invoke anything in DataReceived straight away, instead combine input into something what you can parse (parse means find text between '\', remove first 'L'/'W' and do Int64.Parse), parse it and only invoke results (event for receiving either or both of values?). — Sinatr
– Sinatr, Commented Jan 23, 2015 at 12:22

paul · Accepted Answer · 2015-01-23 12:25:58Z

1

var readQueue = string.Empty;

private void port_DataReceived_1(object sender, SerialDataReceivedEventArgs e)
{
    readQueue += port.ReadExisting();

    while (readQueue.Substring(1).Contains(@"\"))
    {
        var slashPos = readQueue.IndexOf(@"\",1);

        var completeEntry = readQueue.Substring(0, slashPos);

        Console.WriteLine(completeEntry);

        readQueue = readQueue.Substring(slashPos);
    }

}

answered Jan 23, 2015 at 12:25

paul

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