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

Question

Is there a way to read from a USB barcode reader while ignoring the keyboard and not knowing the PID or VID of the USB scanner? I know that there is a way of differentiating between USB scanner input and keyboard input by using the VID and or PID of the USB scanner; this was done using code from http://nicholas.piasecki.name/blog/2009/02/distinguishing-barcode-scanners-from-the-keyboard-in-winforms/ But is there another solution to differentiate between keyboard and USB scanner without putting the scanner's VID or PID in a configuration file (or source code)? The reason for not wanting to put various VIDs or PIDs in a configuration file is that, the application being developed will be deployed on numerous laptops and have arbitrary types of scanners attached to them.

Also, I don't want to configure the scanner's with a starting and or ending sequence that would be outputted, since the scanner is being used by other software on the same machine as well and I don't want to have to change the code on the other software. I don't want to program the barcode reader to be in serial mode either for the same reason mentioned previously.

Answer 1

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