VB.Net การรับค่าจาก Serial port และบันทึกค่าลงในฐานข้อมูล SQL Server

Imports System.Data
Imports System.Data.SqlClient
Imports VB = Microsoft.VisualBasic
Imports System.IO.Ports
Imports System.Threading
Imports System.ComponentModel
Imports System

Public Class Form1

    Dim sqlcon As SqlConnection         'ประกาศตัวแปรเพื่อเชื่อต่อกับฐานข้อมูล
    Dim sqlcmd As SqlCommand
    Dim ds As DataSet
    Dim da As SqlDataAdapter
    Dim myPort As Array 'COM Ports detected on the system will be stored here
    Delegate Sub SetTextCallback(ByVal [text] As String) 'Added to prevent threading errors during receiveing of data

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        myPort = IO.Ports.SerialPort.GetPortNames()
        cmbBaud.Items.Add(9600)
        cmbBaud.Items.Add(19200)
        cmbBaud.Items.Add(38400)
        cmbBaud.Items.Add(57600)
        cmbBaud.Items.Add(115200)
        For i = 0 To UBound(myPort)
            cmbPort.Items.Add(myPort(i))
        Next
        cmbPort.Text = cmbPort.Items.Item(0) 'Set cmbPort text to the first COM port detected
        cmbBaud.Text = cmbBaud.Items.Item(0) 'Set cmbBaud text to the first Baud rate on the list

        btnDisconnect.Enabled = False 'Initially Disconnect Button is Disabled
        Try
            sqlcon = New SqlConnection("Server=TOSHIBA-PC\SQLEXPRESS;Database=parking;Trusted_Connection=True;")    'เชื่อมต่อกับฐานข้อมูล
            sqlcon.Open()

            MsgBox("เชื่อมต่อฐานข้อมูลแล้ว")

            Call showdata2()

        Catch ex As Exception
            MsgBox("Error")
        End Try
    End Sub
    Sub showdata2()
        ds = New DataSet
        da = New SqlDataAdapter("SELECT * FROM inout;", sqlcon)
        da.Fill(ds, "inout")


        DataGridView1.DataSource = ds.Tables("inout")
    End Sub
    Private Sub btnConnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConnect.Click
        SerialPort1.PortName = cmbPort.Text 'Set SerialPort1 to the selected COM port at startup
        SerialPort1.BaudRate = cmbBaud.Text 'Set Baud rate to the selected value on 

        'Other Serial Port Property
        SerialPort1.Parity = IO.Ports.Parity.None
        SerialPort1.StopBits = IO.Ports.StopBits.One
        SerialPort1.DataBits = 8 'Open our serial port
        SerialPort1.Open()

        btnConnect.Enabled = False 'Disable Connect button
        btnDisconnect.Enabled = True 'and Enable Disconnect button
    End Sub
    Private Sub btnDisconnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisconnect.Click
        SerialPort1.Close() 'Close our Serial Port

        btnConnect.Enabled = True
        btnDisconnect.Enabled = False
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Label3.Text = TimeOfDay
        Label4.Text = Date.Today
        Label9.Text = Date.Today
        Label10.Text = TimeOfDay
    End Sub
    Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        ReceivedText(SerialPort1.ReadExisting()) 'Automatically called every time a data is received at the serialPort
    End Sub
    Private Sub ReceivedText(ByVal [text] As String)
        'compares the ID of the creating Thread to the ID of the calling Thread
        Dim dt As String
        dt = DateTime.Now.ToString("dd-MM-yyyy HH:mm:ss")
        Dim strSQL As String
        Dim intNumRows As Integer
        sqlcon = New SqlConnection("Server=TOSHIBA-PC\SQLEXPRESS;Database=parking;Trusted_Connection=True;")
        sqlcon.Open()
        strSQL = "SELECT COUNT(*) FROM member WHERE CardSN = '" & txtSN.Text & "'"
        sqlcmd = New SqlCommand(strSQL, sqlcon)
        intNumRows = sqlcmd.ExecuteScalar()
        If Me.txtSN.InvokeRequired Then
            Dim x As New SetTextCallback(AddressOf ReceivedText)
            Me.Invoke(x, New Object() {(text)})
            If intNumRows > 0 Then
                ds = New DataSet
                da = New SqlDataAdapter("INSERT INTO inout (CardSN,dtin) VALUES ('" & txtSN.Text & "','" & dt & "');", sqlcon)      'บันทึกเวลาเมื่อกดปุ่ม เข้า
                da.Fill(ds, "inout")
                Call showdata2()
                SerialPort1.Write("a")
            Else
                SerialPort1.Write("b")
            End If
        Else
            Me.txtSN.Text &= [text]
        End If
            sqlcon.Close()
    End Sub
    Private Sub cmbPort_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbPort.SelectedIndexChanged
        If SerialPort1.IsOpen = False Then
            SerialPort1.PortName = cmbPort.Text 'pop a message box to user if he is changing ports
        Else 'without disconnecting first.
            MsgBox("port is Closed", vbCritical)
        End If
    End Sub
    Private Sub cmbBaud_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbBaud.SelectedIndexChanged
        If SerialPort1.IsOpen = False Then
            SerialPort1.BaudRate = cmbBaud.Text 'pop a message box to user if he is changing baud rate
        Else 'without disconnecting first.
            MsgBox("port is Closed", vbCritical)
        End If
    End Sub
End Class