Public Class Form1
    Private index As Integer
 
    Private Sub TextBox_KeyUp(ByVal sender As Object, ByVal e As  _
      System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyUp, _
      TextBox2.KeyUp, _
      TextBox3.KeyUp
        Dim tb As TextBox = CType(sender, TextBox)
        tb.CharacterCasing = CharacterCasing.Upper
        If tb.TextLength = 2 And tb.Text <> "XX" Then
            Me.Controls("TextBox" & index.ToString).Focus()
            index += 1
        End If
    End Sub
 
 
End Class