Reading a barcode using a USB barcode scanner along with ignoring keyboard data input while scanner product id and vendor id are not known

There is a way to differentiate between keyboard and USB barcode reader

You can depend on these facts:

1. the code scanned by barcode reader in minmum 4 characters
2. the code scanned by barcode reader ends with RETURN "ENTER"
3. it take less than 50 mseconds to scan the hole barcode

This is a simple form using VS2005 VB contains:

1. textbox1
2. textbox2
3. textbox3
4. Button1
5. Timer1 "the time interval set to 50"ms"

---

Public Class Form1

Dim BarcodeStr As String = ""
Dim IsBarcodeTaken As Boolean = False
Dim Str As String = ""
Dim str3 As String = ""


Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

    If Timer1.Enabled = False Then
        Str = TextBox1.Text
        str3 = TextBox3.Text
    End If

End Sub

Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
    If Timer1.Enabled = False Then
        Timer1.Enabled = True
    End If


    BarcodeStr = BarcodeStr & e.KeyChar
    If Asc(e.KeyChar) = 13 And Len(BarcodeStr) >= 4 Then
        IsBarcodeTaken = True
        TextBox2.Text = BarcodeStr


    End If

End Sub
Private Sub Form1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyUp
    If IsBarcodeTaken = True Then
        TextBox1.Text = Str
        TextBox1.Select(Len(TextBox1.Text), 0)
        Str = ""

        TextBox3.Text = str3
        TextBox3.Select(Len(TextBox3.Text), 0)
        str3 = ""
    End If

End Sub


Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    BarcodeStr = ""
    IsBarcodeTaken = False
    Timer1.Enabled = False
End Sub


Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    TextBox2.Text = ""

End Sub

End Class

Well, I am using a solution pretty like the one from Ehab - I just cleaned up the code a little bit for my application. I am using a custom class for my edit controls (it is doing some other things too) - but these are the important parts:

public class ScannerTextBox : TextBox
{
    public bool BarcodeOnly { get; set; }

    Timer timer;

    private void InitializeComponent()
    {
        this.SuspendLayout();

        this.ResumeLayout(false);
    }

    void timer_Tick(object sender, EventArgs e)
    {
        if (BarcodeOnly == true)
        {
            Text = "";
        }

        timer.Enabled = false;
    }

    protected override void OnKeyPress(KeyPressEventArgs e)
    {
        base.OnKeyPress(e);

        if (BarcodeOnly == true)
        {
            if (timer == null)
            {
                timer = new Timer();
                timer.Interval = 200;
                timer.Tick += new EventHandler(timer_Tick);
                timer.Enabled = false;
            }
            timer.Enabled = true;
        }

        if (e.KeyChar == '\r')
        {
            if (BarcodeOnly == true && timer != null)
            {
                timer.Enabled = false;
            }
        }
    }
}