RFID阅读器和VB.Net应用程序

嗨！我设法创建一个简单的应用程序来通过串口接收数据。现在我尝试使用我的RFID阅读器来显示其中检测到的RFID卡。但我收到的消息或字符串/数据只是"？"。

Hi! I've managed to create a simple application to received a data through serial port. And now i tried to use my RFID Reader to display the RFID card detected in it. But the message or string/data i received is only "?".

Imports System.IO.Ports

Class MainWindow

    Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
        Label1.Visibility = Windows.Visibility.Hidden
        Label2.Visibility = Windows.Visibility.Hidden
        TextBox1.Text = com1.PortName
        TextBox2.Text = com1.BaudRate

        Button1.IsEnabled = False
        Try

            With com1
                .DtrEnable = True
                .RtsEnable = True
                .Handshake = IO.Ports.Handshake.None
                AddHandler .DataReceived, AddressOf DataReceivedHandler
            End With
            com1.Open()

            If com1.IsOpen = True Then
                Label1.Visibility = Windows.Visibility.Visible
            End If
        Catch ex As Exception
            MessageBox.Show("Error")
        End Try
    End Sub

    Private Shared Sub DataReceivedHandler(sender As Object, e As SerialDataReceivedEventArgs)
        Dim sp As SerialPort = CType(sender, SerialPort)
        Dim indata As String = sp.ReadExisting().ToString()
        MessageBox.Show(indata)
    End Sub

    Private Sub Button3_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles Button3.Click
    End Sub

    Private Sub Button1_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles Button1.Click
        com1.Open()
        TextBox1.Text = com1.PortName
        TextBox2.Text = com1.BaudRate
        Button1.IsEnabled = False
        Label1.Visibility = Windows.Visibility.Visible
        Label2.Visibility = Windows.Visibility.Hidden
    End Sub

    Private Sub Button2_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles Button2.Click
        com1.Close()
        Button1.IsEnabled = True
        TextBox1.Text = String.Empty
        TextBox2.Text = String.Empty
        Button1.IsEnabled = True
        Label1.Visibility = Windows.Visibility.Hidden
        Label2.Visibility = Windows.Visibility.Visible
    End Sub

    Private Sub ListBox1_SelectionChanged(sender As System.Object, e As System.Windows.Controls.SelectionChangedEventArgs)

    End Sub
End Class

我如何收到RFID卡的唯一ID？我认为唯一的id是12byte？

How can i received the unique id of the RFID card? i think the unique id is a 12byte?