Question

I have a weighbridge application, where I am using a serial port to get the weights from the weighbridge.

I need to take the weights two times. One with the empty lorry and then with the loaded lorry. I just wonder if I can use two serial ports, one for weighing empty lorry and the other for weighing loaded one? something like

 spWeighIn = new SerialPort("COM1", 2400, Parity.None, 8, StopBits.One);
 spWeighOut = new SerialPort("COM1", 2400, Parity.None, 8, StopBits.One);

and use them simultaneously

Thanks

This is my code:

    SerialPort spWeigh;
    string strResponseWeigh;

    private delegate void SetTextDeleg(string text);

    public MainWindow()
    {
        InitializeComponent();
        this.Loaded += new RoutedEventHandler(MainWindow_Loaded);
    }

    void MainWindow_Loaded(object sender, RoutedEventArgs e)
    {
        spWeigh = new SerialPort("COM1", 2400, Parity.None, 8, StopBits.One);
        spWeigh.RtsEnable = false;
        spWeigh.DtrEnable = false;
        spWeigh.Handshake = Handshake.None;
        spWeigh.ReadTimeout = 10000;   
    }

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        if (!spWeigh.IsOpen)
            spWeigh.Open();
        spWeigh.DataReceived += new SerialDataReceivedEventHandler(spWeigh_DataInReceived);
        spWeigh.Write("W");   
    }

    void spWeigh_DataInReceived(object sender, SerialDataReceivedEventArgs e)
    {
        strResponseWeigh = spWeigh.ReadLine();         
        string wt = strResponseWeigh.Substring(5, 7);
        this.TxtFrstWt.Dispatcher.BeginInvoke(new SetTextDeleg(sin_DataReceived), new object[] { wt });
    }

    private void sin_DataReceived(string data)
    {
        TxtFrstWt.Text = data.Trim();
        TxtDateIn.Text = DateTime.Now.ToString("dd/MM/yyyy");         
    }

    private void button2_Click(object sender, RoutedEventArgs e)
    {
        if (!spWeigh.IsOpen)
            spWeigh.Open();
        spWeigh.DataReceived += new SerialDataReceivedEventHandler(spWeigh_DataOutReceived);
        spWeigh.Write("W");   
    }

    void spWeigh_DataOutReceived(object sender, SerialDataReceivedEventArgs e)
    {
        strResponseWeigh = spWeigh.ReadLine();               
        string wt = strResponseWeigh.Substring(5, 7);               
        this.TxtFrstWt.Dispatcher.BeginInvoke(new SetTextDeleg(sout_DataReceived), new object[] { wt });
    }
    private void sout_DataReceived(string data)
    {
        TxtScndryWt.Text = data.Trim();
        TxtDateOut.Text = DateTime.Now.ToString("dd/MM/yyyy");
    }
}

Answer 1

Let me see if I got this right.

You’re saying that you have a device connected to the serial port and that you need to read the information twice from there, right?

Your code is a bit convulted when dealing with that. I’d redo it in a bit more like this:

SerialPort spWeigh;
string strResponseWeigh;

private delegate void SetTextDeleg(string text);

public MainWindow()
{
    InitializeComponent();
    this.Loaded += new RoutedEventHandler(MainWindow_Loaded);
}

void MainWindow_Loaded(object sender, RoutedEventArgs e)
{
    spWeigh = new SerialPort("COM1", 2400, Parity.None, 8, StopBits.One);
    spWeigh.RtsEnable = false;
    spWeigh.DtrEnable = false;
    spWeigh.Handshake = Handshake.None;
    spWeigh.ReadTimeout = 10000; 
    spWeigh.DataReceived += spWeigh_DataInReceived;
    spWeigh.Open();
}

private void button1_Click(object sender, RoutedEventArgs e)
{
    spWeigh.Write("W"); 
}

void spWeigh_DataInReceived(object sender, SerialDataReceivedEventArgs e)
{
    strResponseWeigh = spWeigh.ReadLine();
    string wt = strResponseWeigh.Substring(5, 7);
    this.TxtFrstWt.Dispatcher.BeginInvoke(new SetTextDeleg(sin_DataReceived), new object[] { wt });
}

private void sin_DataReceived(string data)
{
    TxtFrstWt.Text = data.Trim();
    TxtDateIn.Text = DateTime.Now.ToString("dd/MM/yyyy");
}

You see, you don’t need to attach event handlers every time you click the button, that’s why the line

spWeigh.DataReceived += spWeigh_DataInReceived;

appears to the MainWindow_Loaded event handler.

Trying to open a serial connection more than once might cause some problems, that too went to the loaded event handler.

If I understand the process correctly, every time the device received a W through the serial interface, it spills out the weight in the scale through the same serial port, right?

This way all you need to do is to send a ‘W’ when you click the button and the results should appear on the data received event handler.