How to read specific characters from RS232 serial port data

I am trying to retrieve weight data from a weight indicator which sends data through the RS232 com port ( Converted through USB)

following is the application I designed to receive data

enter image description here

the problem is it shows all the data which is sent from the indicator but the real weight reading is 15,000.

How can I achieve this?

Thank you

Data sheet of the indicator is as follows

Code is as follows

namespace Weight_Test { public partial class Form1 : Form { string dataIN;

    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        string[] ports = SerialPort.GetPortNames();
        cbComPort.Items.AddRange(ports);
        btnOpen.Enabled = true;
        btnClose.Enabled = false;
    }

    private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
    {
        dataIN = serialPort1.ReadExisting();
        this.Invoke(new EventHandler(ShowData));
    }

    private void ShowData(object sender, EventArgs e)
    {
        txtWeight.Text = dataIN;
    }

    private void btnOpen_Click(object sender, EventArgs e)
    {
        try
        {
            serialPort1.PortName = cbComPort.Text;
            serialPort1.BaudRate = Convert.ToInt32(9600);
            serialPort1.DataBits = Convert.ToInt32(8);
            serialPort1.StopBits = (StopBits)Enum.Parse(typeof(StopBits), "One");
            serialPort1.Parity = (Parity)Enum.Parse(typeof(Parity), "None");

            serialPort1.Open();
            btnOpen.Enabled = false;
            btnClose.Enabled = true;
        }
        catch (Exception err)
        {
            MessageBox.Show(err.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            btnOpen.Enabled = true;
            btnClose.Enabled = false;
        }
    }

    private void btnClose_Click(object sender, EventArgs e)
    {
        if (serialPort1.IsOpen)
        {
            serialPort1.Close();
            btnOpen.Enabled = true;
            btnClose.Enabled = false;
        }
    }
}

}