Imports Advantech.Adam

Public Class Form1
    Private m_szIP As String
    Private m_iCount As Integer, m_iPort As Integer
    Private m_iStart As Integer, m_iLength As Integer
    Private m_bRegister As Boolean, m_bStart As Boolean
    Private adamTCP As Advantech.Adam.AdamSocket

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim iIdx As Integer, iPos As Integer, iStart As Integer

        m_bStart = False        ' the action stops at the beginning
        m_bRegister = True      ' set to true to read the register, otherwise, read the coil
        m_szIP = "172.18.3.156" ' modbus slave IP address
        m_iPort = 502           ' modbus port
        m_iStart = 1            ' modbus starting address
        m_iLength = 8           ' modbus reading length
        adamTCP = New AdamSocket
        adamTCP.SetTimeout(1000, 1000, 1000)

        ' fill the ListView
        If m_bRegister = True Then ' The initial register list 
            iStart = 40000 + m_iStart ' The register starting position  (4X references)
            For iIdx = 0 To m_iLength - 1
                iPos = iStart + iIdx
                listViewModbusCur.Items.Add(New ListViewItem(iPos.ToString()))
                listViewModbusCur.Items(iIdx).SubItems.Add("Word")
                listViewModbusCur.Items(iIdx).SubItems.Add("*****")
                listViewModbusCur.Items(iIdx).SubItems.Add("****")
            Next iIdx
        Else ' The initial coil list
            iStart = m_iStart  ' The coil starting position (0X references)
            For iIdx = 0 To m_iLength - 1
                iPos = iStart + iIdx
                listViewModbusCur.Items.Add(New ListViewItem(iPos.ToString("00000")))
                listViewModbusCur.Items(iIdx).SubItems.Add("Bit")
                listViewModbusCur.Items(iIdx).SubItems.Add("*****")
                listViewModbusCur.Items(iIdx).SubItems.Add("****")
            Next iIdx
        End If
    End Sub

    Private Sub Form1_Closing(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
        If m_bStart = True Then
            Timer1.Enabled = False  'disable timer
            adamTCP.Disconnect()    'disconnect the slave
        End If
    End Sub

    Private Sub buttonStart_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles buttonStart.Click
        If m_bStart = True Then ' was started
            m_bStart = False    ' starting flag
            Timer1.Enabled = False ' disable timer
            adamTCP.Disconnect()    'disconnect the slave
            buttonStart.Text = "Start"
        Else ' was stoped
            If adamTCP.Connect(m_szIP, Net.Sockets.ProtocolType.Tcp, m_iPort) = True Then
                m_iCount = 0 ' reset the reading counter
                Timer1.Enabled = True ' enable timer
                buttonStart.Text = "Stop"
                m_bStart = True 'starting flag
            Else
                MessageBox.Show("Connect to " + m_szIP + " failed", "Error")
            End If
        End If
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Dim iIdx As Integer
        Dim iData() As Integer
        Dim bData() As Boolean


        If m_bRegister = True Then ' Read registers (4X references)
            If adamTCP.Modbus().ReadHoldingRegs(m_iStart, m_iLength, iData) = True Then
                m_iCount = m_iCount + 1 ' increment the reading counter
                txtStatus.Text = "Read registers " + m_iCount.ToString() + " times..."
                ' update ListView
                For iIdx = 0 To m_iLength - 1
                    listViewModbusCur.Items(iIdx).SubItems(2).Text = iData(iIdx).ToString()   ' show value in decimal
                    listViewModbusCur.Items(iIdx).SubItems(3).Text = iData(iIdx).ToString("X04") ' show value in hexdecimal
                Next iIdx

            Else
                txtStatus.Text = "Read registers failed!" ' show error message in "txtStatus"
            End If
        Else    ' read coil (0X) data from slave
            If adamTCP.Modbus().ReadCoilStatus(m_iStart, m_iLength, bData) = True Then
                m_iCount = m_iCount + 1 ' increment the reading counter
                txtStatus.Text = "Read coil " + m_iCount.ToString() + " times..."
                ' update ListView
                For iIdx = 0 To m_iLength - 1
                    listViewModbusCur.Items(iIdx).SubItems(2).Text = bData(iIdx).ToString() ' show value
                Next iIdx
            Else
                txtStatus.Text = "Read coil failed!" ' show error message in "txtStatus"
            End If
        End If
    End Sub
End Class