transmitting through rs 232 port using vb.net

Hello experts, i would like to transmit some data through my 232 port when a button is clicked on my webform.  I have no idea how to do this using vb.net.  What i have done is built a check list webpage, and when the check list is completed by the user, the user clicks a button and some data is transmitted through the 232 port, and picked up by a plc.  Could someone show me or give an example of coding this, using vb.net?
tentavariousAsked:
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armoghanCommented:
Rs232 is a protcol and the name of cable,
I can provide you links to information but full code is against the rules of EE

http://www.mentalis.org/classlib/class.php?id=15
http://www.htservices.com/Tools/VBandC/SerialCommunications.htm
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tentavariousAuthor Commented:
Does vb.net come with a class that deals with rs 232 port, or can i download it from microsoft for free?
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Bob LearnedCommented:
Sax.NET comes with the Visual Basic.NET Resource Kit for 2003.  It is a community version, and provides simple RS-232 support, and should fit your requirements.

Bob
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tentavariousAuthor Commented:
Isnt there a way i can do it without using another tool?  I thought vb.net had a class that dealt with this where i could set up the properites of what com port to use and the baud rate and so on?
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Bob LearnedCommented:
Nope.  VB.NET 2002 and 2003 are sadly missing that functionality.  Maybe in 2005 :)

Bob
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tentavariousAuthor Commented:
Could you explain to me what all the properties of the com port are used for. For example i know baud rate is the speed, but what does parity mean?
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Bob LearnedCommented:
Aaah, a serial communication lesson:  

Introduction to Serial Communications:
http://www.taltech.com/TALtech_web/resources/intro-sc.html

"A parity bit affords a small amount of error checking, to help detect data corruption that might occur during transmission. You can choose either even parity, odd parity, mark parity, space parity or none at all. When even or odd parity is being used, the number of marks (logical 1 bits) in each data byte are counted, and a single bit is transmitted following the data bits to indicate whether the number of 1 bits just sent is even or odd."

Look at the "Baud vs. Bits per Second" to make sure that you understand that it is not Bits/Second.

Bob
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tentavariousAuthor Commented:
Thanks for all the input
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tentavariousAuthor Commented:
I did find this code that uses vb.net and win forms to establish a serial connection, and it doesnt seem like it is using sax.  Could you explain how they are doing it. The only import is the system.text

Imports System.Text

Public Class frmMain
      Inherits System.Windows.Forms.Form

    ' Declare necessary class variables.
    Private m_CommPort As New Rs232()
    Private m_IsModemFound As Boolean = False
    Private m_ModemPort As Integer = 0

#Region " Windows Form Designer generated code "

      Public Sub New()
            MyBase.New()

            'This call is required by the Windows Form Designer.
            InitializeComponent()

            'Add any initialization after the InitializeComponent() call

            ' So that we only need to set the title of the application once,
            ' we use the AssemblyInfo class (defined in the AssemblyInfo.vb file)
            ' to read the AssemblyTitle attribute.
            Dim ainfo As New AssemblyInfo()

            Me.Text = ainfo.Title
            Me.mnuAbout.Text = String.Format("&About {0} ...", ainfo.Title)

      End Sub

      'Form overrides dispose to clean up the component list.
      Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
            If disposing Then
                  If Not (components Is Nothing) Then
                        components.Dispose()
                  End If
            End If
            MyBase.Dispose(disposing)
      End Sub

      'Required by the Windows Form Designer
      Private components As System.ComponentModel.IContainer

      'NOTE: The following procedure is required by the Windows Form Designer
      'It can be modified using the Windows Form Designer.  
      'Do not modify it using the code editor.
      Friend WithEvents mnuMain As System.Windows.Forms.MainMenu
      Friend WithEvents mnuFile As System.Windows.Forms.MenuItem
      Friend WithEvents mnuExit As System.Windows.Forms.MenuItem
      Friend WithEvents mnuHelp As System.Windows.Forms.MenuItem
      Friend WithEvents mnuAbout As System.Windows.Forms.MenuItem
    Friend WithEvents txtStatus As System.Windows.Forms.TextBox
    Friend WithEvents tmrReadCommPort As System.Windows.Forms.Timer
    Friend WithEvents clstPorts As System.Windows.Forms.CheckedListBox
    Friend WithEvents btnCheckForPorts As System.Windows.Forms.Button
    Friend WithEvents btnCheckModems As System.Windows.Forms.Button
    Friend WithEvents txtSelectedModem As System.Windows.Forms.TextBox
    Friend WithEvents btnSendATCommand As System.Windows.Forms.Button
    Friend WithEvents txtUserCommand As System.Windows.Forms.TextBox
    Friend WithEvents btnSendUserCommand As System.Windows.Forms.Button
    Friend WithEvents btnClear As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.components = New System.ComponentModel.Container()
        Dim resources As System.Resources.ResourceManager = New System.Resources.ResourceManager(GetType(frmMain))
        Me.mnuMain = New System.Windows.Forms.MainMenu()
        Me.mnuFile = New System.Windows.Forms.MenuItem()
        Me.mnuExit = New System.Windows.Forms.MenuItem()
        Me.mnuHelp = New System.Windows.Forms.MenuItem()
        Me.mnuAbout = New System.Windows.Forms.MenuItem()
        Me.btnCheckForPorts = New System.Windows.Forms.Button()
        Me.txtStatus = New System.Windows.Forms.TextBox()
        Me.tmrReadCommPort = New System.Windows.Forms.Timer(Me.components)
        Me.clstPorts = New System.Windows.Forms.CheckedListBox()
        Me.btnCheckModems = New System.Windows.Forms.Button()
        Me.txtSelectedModem = New System.Windows.Forms.TextBox()
        Me.btnSendATCommand = New System.Windows.Forms.Button()
        Me.btnSendUserCommand = New System.Windows.Forms.Button()
        Me.txtUserCommand = New System.Windows.Forms.TextBox()
        Me.btnClear = New System.Windows.Forms.Button()
        Me.SuspendLayout()
        '
        'mnuMain
        '
        Me.mnuMain.MenuItems.AddRange(New System.Windows.Forms.MenuItem() {Me.mnuFile, Me.mnuHelp})
        Me.mnuMain.RightToLeft = CType(resources.GetObject("mnuMain.RightToLeft"), System.Windows.Forms.RightToLeft)
        '
        'mnuFile
        '
        Me.mnuFile.Enabled = CType(resources.GetObject("mnuFile.Enabled"), Boolean)
        Me.mnuFile.Index = 0
        Me.mnuFile.MenuItems.AddRange(New System.Windows.Forms.MenuItem() {Me.mnuExit})
        Me.mnuFile.Shortcut = CType(resources.GetObject("mnuFile.Shortcut"), System.Windows.Forms.Shortcut)
        Me.mnuFile.ShowShortcut = CType(resources.GetObject("mnuFile.ShowShortcut"), Boolean)
        Me.mnuFile.Text = resources.GetString("mnuFile.Text")
        Me.mnuFile.Visible = CType(resources.GetObject("mnuFile.Visible"), Boolean)
        '
        'mnuExit
        '
        Me.mnuExit.Enabled = CType(resources.GetObject("mnuExit.Enabled"), Boolean)
        Me.mnuExit.Index = 0
        Me.mnuExit.Shortcut = CType(resources.GetObject("mnuExit.Shortcut"), System.Windows.Forms.Shortcut)
        Me.mnuExit.ShowShortcut = CType(resources.GetObject("mnuExit.ShowShortcut"), Boolean)
        Me.mnuExit.Text = resources.GetString("mnuExit.Text")
        Me.mnuExit.Visible = CType(resources.GetObject("mnuExit.Visible"), Boolean)
        '
        'mnuHelp
        '
        Me.mnuHelp.Enabled = CType(resources.GetObject("mnuHelp.Enabled"), Boolean)
        Me.mnuHelp.Index = 1
        Me.mnuHelp.MenuItems.AddRange(New System.Windows.Forms.MenuItem() {Me.mnuAbout})
        Me.mnuHelp.Shortcut = CType(resources.GetObject("mnuHelp.Shortcut"), System.Windows.Forms.Shortcut)
        Me.mnuHelp.ShowShortcut = CType(resources.GetObject("mnuHelp.ShowShortcut"), Boolean)
        Me.mnuHelp.Text = resources.GetString("mnuHelp.Text")
        Me.mnuHelp.Visible = CType(resources.GetObject("mnuHelp.Visible"), Boolean)
        '
        'mnuAbout
        '
        Me.mnuAbout.Enabled = CType(resources.GetObject("mnuAbout.Enabled"), Boolean)
        Me.mnuAbout.Index = 0
        Me.mnuAbout.Shortcut = CType(resources.GetObject("mnuAbout.Shortcut"), System.Windows.Forms.Shortcut)
        Me.mnuAbout.ShowShortcut = CType(resources.GetObject("mnuAbout.ShowShortcut"), Boolean)
        Me.mnuAbout.Text = resources.GetString("mnuAbout.Text")
        Me.mnuAbout.Visible = CType(resources.GetObject("mnuAbout.Visible"), Boolean)
        '
        'btnCheckForPorts
        '
        Me.btnCheckForPorts.AccessibleDescription = resources.GetString("btnCheckForPorts.AccessibleDescription")
        Me.btnCheckForPorts.AccessibleName = resources.GetString("btnCheckForPorts.AccessibleName")
        Me.btnCheckForPorts.Anchor = CType(resources.GetObject("btnCheckForPorts.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.btnCheckForPorts.BackgroundImage = CType(resources.GetObject("btnCheckForPorts.BackgroundImage"), System.Drawing.Image)
        Me.btnCheckForPorts.Dock = CType(resources.GetObject("btnCheckForPorts.Dock"), System.Windows.Forms.DockStyle)
        Me.btnCheckForPorts.Enabled = CType(resources.GetObject("btnCheckForPorts.Enabled"), Boolean)
        Me.btnCheckForPorts.FlatStyle = CType(resources.GetObject("btnCheckForPorts.FlatStyle"), System.Windows.Forms.FlatStyle)
        Me.btnCheckForPorts.Font = CType(resources.GetObject("btnCheckForPorts.Font"), System.Drawing.Font)
        Me.btnCheckForPorts.Image = CType(resources.GetObject("btnCheckForPorts.Image"), System.Drawing.Image)
        Me.btnCheckForPorts.ImageAlign = CType(resources.GetObject("btnCheckForPorts.ImageAlign"), System.Drawing.ContentAlignment)
        Me.btnCheckForPorts.ImageIndex = CType(resources.GetObject("btnCheckForPorts.ImageIndex"), Integer)
        Me.btnCheckForPorts.ImeMode = CType(resources.GetObject("btnCheckForPorts.ImeMode"), System.Windows.Forms.ImeMode)
        Me.btnCheckForPorts.Location = CType(resources.GetObject("btnCheckForPorts.Location"), System.Drawing.Point)
        Me.btnCheckForPorts.Name = "btnCheckForPorts"
        Me.btnCheckForPorts.RightToLeft = CType(resources.GetObject("btnCheckForPorts.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.btnCheckForPorts.Size = CType(resources.GetObject("btnCheckForPorts.Size"), System.Drawing.Size)
        Me.btnCheckForPorts.TabIndex = CType(resources.GetObject("btnCheckForPorts.TabIndex"), Integer)
        Me.btnCheckForPorts.Text = resources.GetString("btnCheckForPorts.Text")
        Me.btnCheckForPorts.TextAlign = CType(resources.GetObject("btnCheckForPorts.TextAlign"), System.Drawing.ContentAlignment)
        Me.btnCheckForPorts.Visible = CType(resources.GetObject("btnCheckForPorts.Visible"), Boolean)
        '
        'txtStatus
        '
        Me.txtStatus.AccessibleDescription = resources.GetString("txtStatus.AccessibleDescription")
        Me.txtStatus.AccessibleName = resources.GetString("txtStatus.AccessibleName")
        Me.txtStatus.Anchor = CType(resources.GetObject("txtStatus.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.txtStatus.AutoSize = CType(resources.GetObject("txtStatus.AutoSize"), Boolean)
        Me.txtStatus.BackgroundImage = CType(resources.GetObject("txtStatus.BackgroundImage"), System.Drawing.Image)
        Me.txtStatus.Dock = CType(resources.GetObject("txtStatus.Dock"), System.Windows.Forms.DockStyle)
        Me.txtStatus.Enabled = CType(resources.GetObject("txtStatus.Enabled"), Boolean)
        Me.txtStatus.Font = CType(resources.GetObject("txtStatus.Font"), System.Drawing.Font)
        Me.txtStatus.ImeMode = CType(resources.GetObject("txtStatus.ImeMode"), System.Windows.Forms.ImeMode)
        Me.txtStatus.Location = CType(resources.GetObject("txtStatus.Location"), System.Drawing.Point)
        Me.txtStatus.MaxLength = CType(resources.GetObject("txtStatus.MaxLength"), Integer)
        Me.txtStatus.Multiline = CType(resources.GetObject("txtStatus.Multiline"), Boolean)
        Me.txtStatus.Name = "txtStatus"
        Me.txtStatus.PasswordChar = CType(resources.GetObject("txtStatus.PasswordChar"), Char)
        Me.txtStatus.ReadOnly = True
        Me.txtStatus.RightToLeft = CType(resources.GetObject("txtStatus.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.txtStatus.ScrollBars = CType(resources.GetObject("txtStatus.ScrollBars"), System.Windows.Forms.ScrollBars)
        Me.txtStatus.Size = CType(resources.GetObject("txtStatus.Size"), System.Drawing.Size)
        Me.txtStatus.TabIndex = CType(resources.GetObject("txtStatus.TabIndex"), Integer)
        Me.txtStatus.Text = resources.GetString("txtStatus.Text")
        Me.txtStatus.TextAlign = CType(resources.GetObject("txtStatus.TextAlign"), System.Windows.Forms.HorizontalAlignment)
        Me.txtStatus.Visible = CType(resources.GetObject("txtStatus.Visible"), Boolean)
        Me.txtStatus.WordWrap = CType(resources.GetObject("txtStatus.WordWrap"), Boolean)
        '
        'tmrReadCommPort
        '
        '
        'clstPorts
        '
        Me.clstPorts.AccessibleDescription = resources.GetString("clstPorts.AccessibleDescription")
        Me.clstPorts.AccessibleName = resources.GetString("clstPorts.AccessibleName")
        Me.clstPorts.Anchor = CType(resources.GetObject("clstPorts.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.clstPorts.BackgroundImage = CType(resources.GetObject("clstPorts.BackgroundImage"), System.Drawing.Image)
        Me.clstPorts.ColumnWidth = CType(resources.GetObject("clstPorts.ColumnWidth"), Integer)
        Me.clstPorts.Dock = CType(resources.GetObject("clstPorts.Dock"), System.Windows.Forms.DockStyle)
        Me.clstPorts.Enabled = CType(resources.GetObject("clstPorts.Enabled"), Boolean)
        Me.clstPorts.Font = CType(resources.GetObject("clstPorts.Font"), System.Drawing.Font)
        Me.clstPorts.HorizontalExtent = CType(resources.GetObject("clstPorts.HorizontalExtent"), Integer)
        Me.clstPorts.HorizontalScrollbar = CType(resources.GetObject("clstPorts.HorizontalScrollbar"), Boolean)
        Me.clstPorts.ImeMode = CType(resources.GetObject("clstPorts.ImeMode"), System.Windows.Forms.ImeMode)
        Me.clstPorts.IntegralHeight = CType(resources.GetObject("clstPorts.IntegralHeight"), Boolean)
        Me.clstPorts.Items.AddRange(New Object() {resources.GetString("clstPorts.Items.Items"), resources.GetString("clstPorts.Items.Items1"), resources.GetString("clstPorts.Items.Items2"), resources.GetString("clstPorts.Items.Items3")})
        Me.clstPorts.Location = CType(resources.GetObject("clstPorts.Location"), System.Drawing.Point)
        Me.clstPorts.Name = "clstPorts"
        Me.clstPorts.RightToLeft = CType(resources.GetObject("clstPorts.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.clstPorts.ScrollAlwaysVisible = CType(resources.GetObject("clstPorts.ScrollAlwaysVisible"), Boolean)
        Me.clstPorts.Size = CType(resources.GetObject("clstPorts.Size"), System.Drawing.Size)
        Me.clstPorts.TabIndex = CType(resources.GetObject("clstPorts.TabIndex"), Integer)
        Me.clstPorts.TabStop = False
        Me.clstPorts.Visible = CType(resources.GetObject("clstPorts.Visible"), Boolean)
        '
        'btnCheckModems
        '
        Me.btnCheckModems.AccessibleDescription = resources.GetString("btnCheckModems.AccessibleDescription")
        Me.btnCheckModems.AccessibleName = resources.GetString("btnCheckModems.AccessibleName")
        Me.btnCheckModems.Anchor = CType(resources.GetObject("btnCheckModems.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.btnCheckModems.BackgroundImage = CType(resources.GetObject("btnCheckModems.BackgroundImage"), System.Drawing.Image)
        Me.btnCheckModems.Dock = CType(resources.GetObject("btnCheckModems.Dock"), System.Windows.Forms.DockStyle)
        Me.btnCheckModems.Enabled = CType(resources.GetObject("btnCheckModems.Enabled"), Boolean)
        Me.btnCheckModems.FlatStyle = CType(resources.GetObject("btnCheckModems.FlatStyle"), System.Windows.Forms.FlatStyle)
        Me.btnCheckModems.Font = CType(resources.GetObject("btnCheckModems.Font"), System.Drawing.Font)
        Me.btnCheckModems.Image = CType(resources.GetObject("btnCheckModems.Image"), System.Drawing.Image)
        Me.btnCheckModems.ImageAlign = CType(resources.GetObject("btnCheckModems.ImageAlign"), System.Drawing.ContentAlignment)
        Me.btnCheckModems.ImageIndex = CType(resources.GetObject("btnCheckModems.ImageIndex"), Integer)
        Me.btnCheckModems.ImeMode = CType(resources.GetObject("btnCheckModems.ImeMode"), System.Windows.Forms.ImeMode)
        Me.btnCheckModems.Location = CType(resources.GetObject("btnCheckModems.Location"), System.Drawing.Point)
        Me.btnCheckModems.Name = "btnCheckModems"
        Me.btnCheckModems.RightToLeft = CType(resources.GetObject("btnCheckModems.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.btnCheckModems.Size = CType(resources.GetObject("btnCheckModems.Size"), System.Drawing.Size)
        Me.btnCheckModems.TabIndex = CType(resources.GetObject("btnCheckModems.TabIndex"), Integer)
        Me.btnCheckModems.Text = resources.GetString("btnCheckModems.Text")
        Me.btnCheckModems.TextAlign = CType(resources.GetObject("btnCheckModems.TextAlign"), System.Drawing.ContentAlignment)
        Me.btnCheckModems.Visible = CType(resources.GetObject("btnCheckModems.Visible"), Boolean)
        '
        'txtSelectedModem
        '
        Me.txtSelectedModem.AccessibleDescription = resources.GetString("txtSelectedModem.AccessibleDescription")
        Me.txtSelectedModem.AccessibleName = resources.GetString("txtSelectedModem.AccessibleName")
        Me.txtSelectedModem.Anchor = CType(resources.GetObject("txtSelectedModem.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.txtSelectedModem.AutoSize = CType(resources.GetObject("txtSelectedModem.AutoSize"), Boolean)
        Me.txtSelectedModem.BackgroundImage = CType(resources.GetObject("txtSelectedModem.BackgroundImage"), System.Drawing.Image)
        Me.txtSelectedModem.Dock = CType(resources.GetObject("txtSelectedModem.Dock"), System.Windows.Forms.DockStyle)
        Me.txtSelectedModem.Enabled = CType(resources.GetObject("txtSelectedModem.Enabled"), Boolean)
        Me.txtSelectedModem.Font = CType(resources.GetObject("txtSelectedModem.Font"), System.Drawing.Font)
        Me.txtSelectedModem.ImeMode = CType(resources.GetObject("txtSelectedModem.ImeMode"), System.Windows.Forms.ImeMode)
        Me.txtSelectedModem.Location = CType(resources.GetObject("txtSelectedModem.Location"), System.Drawing.Point)
        Me.txtSelectedModem.MaxLength = CType(resources.GetObject("txtSelectedModem.MaxLength"), Integer)
        Me.txtSelectedModem.Multiline = CType(resources.GetObject("txtSelectedModem.Multiline"), Boolean)
        Me.txtSelectedModem.Name = "txtSelectedModem"
        Me.txtSelectedModem.PasswordChar = CType(resources.GetObject("txtSelectedModem.PasswordChar"), Char)
        Me.txtSelectedModem.RightToLeft = CType(resources.GetObject("txtSelectedModem.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.txtSelectedModem.ScrollBars = CType(resources.GetObject("txtSelectedModem.ScrollBars"), System.Windows.Forms.ScrollBars)
        Me.txtSelectedModem.Size = CType(resources.GetObject("txtSelectedModem.Size"), System.Drawing.Size)
        Me.txtSelectedModem.TabIndex = CType(resources.GetObject("txtSelectedModem.TabIndex"), Integer)
        Me.txtSelectedModem.Text = resources.GetString("txtSelectedModem.Text")
        Me.txtSelectedModem.TextAlign = CType(resources.GetObject("txtSelectedModem.TextAlign"), System.Windows.Forms.HorizontalAlignment)
        Me.txtSelectedModem.Visible = CType(resources.GetObject("txtSelectedModem.Visible"), Boolean)
        Me.txtSelectedModem.WordWrap = CType(resources.GetObject("txtSelectedModem.WordWrap"), Boolean)
        '
        'btnSendATCommand
        '
        Me.btnSendATCommand.AccessibleDescription = resources.GetString("btnSendATCommand.AccessibleDescription")
        Me.btnSendATCommand.AccessibleName = resources.GetString("btnSendATCommand.AccessibleName")
        Me.btnSendATCommand.Anchor = CType(resources.GetObject("btnSendATCommand.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.btnSendATCommand.BackgroundImage = CType(resources.GetObject("btnSendATCommand.BackgroundImage"), System.Drawing.Image)
        Me.btnSendATCommand.Dock = CType(resources.GetObject("btnSendATCommand.Dock"), System.Windows.Forms.DockStyle)
        Me.btnSendATCommand.Enabled = CType(resources.GetObject("btnSendATCommand.Enabled"), Boolean)
        Me.btnSendATCommand.FlatStyle = CType(resources.GetObject("btnSendATCommand.FlatStyle"), System.Windows.Forms.FlatStyle)
        Me.btnSendATCommand.Font = CType(resources.GetObject("btnSendATCommand.Font"), System.Drawing.Font)
        Me.btnSendATCommand.Image = CType(resources.GetObject("btnSendATCommand.Image"), System.Drawing.Image)
        Me.btnSendATCommand.ImageAlign = CType(resources.GetObject("btnSendATCommand.ImageAlign"), System.Drawing.ContentAlignment)
        Me.btnSendATCommand.ImageIndex = CType(resources.GetObject("btnSendATCommand.ImageIndex"), Integer)
        Me.btnSendATCommand.ImeMode = CType(resources.GetObject("btnSendATCommand.ImeMode"), System.Windows.Forms.ImeMode)
        Me.btnSendATCommand.Location = CType(resources.GetObject("btnSendATCommand.Location"), System.Drawing.Point)
        Me.btnSendATCommand.Name = "btnSendATCommand"
        Me.btnSendATCommand.RightToLeft = CType(resources.GetObject("btnSendATCommand.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.btnSendATCommand.Size = CType(resources.GetObject("btnSendATCommand.Size"), System.Drawing.Size)
        Me.btnSendATCommand.TabIndex = CType(resources.GetObject("btnSendATCommand.TabIndex"), Integer)
        Me.btnSendATCommand.Text = resources.GetString("btnSendATCommand.Text")
        Me.btnSendATCommand.TextAlign = CType(resources.GetObject("btnSendATCommand.TextAlign"), System.Drawing.ContentAlignment)
        Me.btnSendATCommand.Visible = CType(resources.GetObject("btnSendATCommand.Visible"), Boolean)
        '
        'btnSendUserCommand
        '
        Me.btnSendUserCommand.AccessibleDescription = resources.GetString("btnSendUserCommand.AccessibleDescription")
        Me.btnSendUserCommand.AccessibleName = resources.GetString("btnSendUserCommand.AccessibleName")
        Me.btnSendUserCommand.Anchor = CType(resources.GetObject("btnSendUserCommand.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.btnSendUserCommand.BackgroundImage = CType(resources.GetObject("btnSendUserCommand.BackgroundImage"), System.Drawing.Image)
        Me.btnSendUserCommand.Dock = CType(resources.GetObject("btnSendUserCommand.Dock"), System.Windows.Forms.DockStyle)
        Me.btnSendUserCommand.Enabled = CType(resources.GetObject("btnSendUserCommand.Enabled"), Boolean)
        Me.btnSendUserCommand.FlatStyle = CType(resources.GetObject("btnSendUserCommand.FlatStyle"), System.Windows.Forms.FlatStyle)
        Me.btnSendUserCommand.Font = CType(resources.GetObject("btnSendUserCommand.Font"), System.Drawing.Font)
        Me.btnSendUserCommand.Image = CType(resources.GetObject("btnSendUserCommand.Image"), System.Drawing.Image)
        Me.btnSendUserCommand.ImageAlign = CType(resources.GetObject("btnSendUserCommand.ImageAlign"), System.Drawing.ContentAlignment)
        Me.btnSendUserCommand.ImageIndex = CType(resources.GetObject("btnSendUserCommand.ImageIndex"), Integer)
        Me.btnSendUserCommand.ImeMode = CType(resources.GetObject("btnSendUserCommand.ImeMode"), System.Windows.Forms.ImeMode)
        Me.btnSendUserCommand.Location = CType(resources.GetObject("btnSendUserCommand.Location"), System.Drawing.Point)
        Me.btnSendUserCommand.Name = "btnSendUserCommand"
        Me.btnSendUserCommand.RightToLeft = CType(resources.GetObject("btnSendUserCommand.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.btnSendUserCommand.Size = CType(resources.GetObject("btnSendUserCommand.Size"), System.Drawing.Size)
        Me.btnSendUserCommand.TabIndex = CType(resources.GetObject("btnSendUserCommand.TabIndex"), Integer)
        Me.btnSendUserCommand.Text = resources.GetString("btnSendUserCommand.Text")
        Me.btnSendUserCommand.TextAlign = CType(resources.GetObject("btnSendUserCommand.TextAlign"), System.Drawing.ContentAlignment)
        Me.btnSendUserCommand.Visible = CType(resources.GetObject("btnSendUserCommand.Visible"), Boolean)
        '
        'txtUserCommand
        '
        Me.txtUserCommand.AccessibleDescription = resources.GetString("txtUserCommand.AccessibleDescription")
        Me.txtUserCommand.AccessibleName = resources.GetString("txtUserCommand.AccessibleName")
        Me.txtUserCommand.Anchor = CType(resources.GetObject("txtUserCommand.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.txtUserCommand.AutoSize = CType(resources.GetObject("txtUserCommand.AutoSize"), Boolean)
        Me.txtUserCommand.BackgroundImage = CType(resources.GetObject("txtUserCommand.BackgroundImage"), System.Drawing.Image)
        Me.txtUserCommand.Dock = CType(resources.GetObject("txtUserCommand.Dock"), System.Windows.Forms.DockStyle)
        Me.txtUserCommand.Enabled = CType(resources.GetObject("txtUserCommand.Enabled"), Boolean)
        Me.txtUserCommand.Font = CType(resources.GetObject("txtUserCommand.Font"), System.Drawing.Font)
        Me.txtUserCommand.ImeMode = CType(resources.GetObject("txtUserCommand.ImeMode"), System.Windows.Forms.ImeMode)
        Me.txtUserCommand.Location = CType(resources.GetObject("txtUserCommand.Location"), System.Drawing.Point)
        Me.txtUserCommand.MaxLength = CType(resources.GetObject("txtUserCommand.MaxLength"), Integer)
        Me.txtUserCommand.Multiline = CType(resources.GetObject("txtUserCommand.Multiline"), Boolean)
        Me.txtUserCommand.Name = "txtUserCommand"
        Me.txtUserCommand.PasswordChar = CType(resources.GetObject("txtUserCommand.PasswordChar"), Char)
        Me.txtUserCommand.RightToLeft = CType(resources.GetObject("txtUserCommand.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.txtUserCommand.ScrollBars = CType(resources.GetObject("txtUserCommand.ScrollBars"), System.Windows.Forms.ScrollBars)
        Me.txtUserCommand.Size = CType(resources.GetObject("txtUserCommand.Size"), System.Drawing.Size)
        Me.txtUserCommand.TabIndex = CType(resources.GetObject("txtUserCommand.TabIndex"), Integer)
        Me.txtUserCommand.Text = resources.GetString("txtUserCommand.Text")
        Me.txtUserCommand.TextAlign = CType(resources.GetObject("txtUserCommand.TextAlign"), System.Windows.Forms.HorizontalAlignment)
        Me.txtUserCommand.Visible = CType(resources.GetObject("txtUserCommand.Visible"), Boolean)
        Me.txtUserCommand.WordWrap = CType(resources.GetObject("txtUserCommand.WordWrap"), Boolean)
        '
        'btnClear
        '
        Me.btnClear.AccessibleDescription = resources.GetString("btnClear.AccessibleDescription")
        Me.btnClear.AccessibleName = resources.GetString("btnClear.AccessibleName")
        Me.btnClear.Anchor = CType(resources.GetObject("btnClear.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.btnClear.BackgroundImage = CType(resources.GetObject("btnClear.BackgroundImage"), System.Drawing.Image)
        Me.btnClear.Dock = CType(resources.GetObject("btnClear.Dock"), System.Windows.Forms.DockStyle)
        Me.btnClear.Enabled = CType(resources.GetObject("btnClear.Enabled"), Boolean)
        Me.btnClear.FlatStyle = CType(resources.GetObject("btnClear.FlatStyle"), System.Windows.Forms.FlatStyle)
        Me.btnClear.Font = CType(resources.GetObject("btnClear.Font"), System.Drawing.Font)
        Me.btnClear.Image = CType(resources.GetObject("btnClear.Image"), System.Drawing.Image)
        Me.btnClear.ImageAlign = CType(resources.GetObject("btnClear.ImageAlign"), System.Drawing.ContentAlignment)
        Me.btnClear.ImageIndex = CType(resources.GetObject("btnClear.ImageIndex"), Integer)
        Me.btnClear.ImeMode = CType(resources.GetObject("btnClear.ImeMode"), System.Windows.Forms.ImeMode)
        Me.btnClear.Location = CType(resources.GetObject("btnClear.Location"), System.Drawing.Point)
        Me.btnClear.Name = "btnClear"
        Me.btnClear.RightToLeft = CType(resources.GetObject("btnClear.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.btnClear.Size = CType(resources.GetObject("btnClear.Size"), System.Drawing.Size)
        Me.btnClear.TabIndex = CType(resources.GetObject("btnClear.TabIndex"), Integer)
        Me.btnClear.Text = resources.GetString("btnClear.Text")
        Me.btnClear.TextAlign = CType(resources.GetObject("btnClear.TextAlign"), System.Drawing.ContentAlignment)
        Me.btnClear.Visible = CType(resources.GetObject("btnClear.Visible"), Boolean)
        '
        'frmMain
        '
        Me.AccessibleDescription = CType(resources.GetObject("$this.AccessibleDescription"), String)
        Me.AccessibleName = CType(resources.GetObject("$this.AccessibleName"), String)
        Me.Anchor = CType(resources.GetObject("$this.Anchor"), System.Windows.Forms.AnchorStyles)
        Me.AutoScaleBaseSize = CType(resources.GetObject("$this.AutoScaleBaseSize"), System.Drawing.Size)
        Me.AutoScroll = CType(resources.GetObject("$this.AutoScroll"), Boolean)
        Me.AutoScrollMargin = CType(resources.GetObject("$this.AutoScrollMargin"), System.Drawing.Size)
        Me.AutoScrollMinSize = CType(resources.GetObject("$this.AutoScrollMinSize"), System.Drawing.Size)
        Me.BackgroundImage = CType(resources.GetObject("$this.BackgroundImage"), System.Drawing.Image)
        Me.ClientSize = CType(resources.GetObject("$this.ClientSize"), System.Drawing.Size)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.btnClear, Me.txtUserCommand, Me.btnSendUserCommand, Me.btnSendATCommand, Me.txtSelectedModem, Me.btnCheckModems, Me.clstPorts, Me.txtStatus, Me.btnCheckForPorts})
        Me.Dock = CType(resources.GetObject("$this.Dock"), System.Windows.Forms.DockStyle)
        Me.Enabled = CType(resources.GetObject("$this.Enabled"), Boolean)
        Me.Font = CType(resources.GetObject("$this.Font"), System.Drawing.Font)
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle
        Me.Icon = CType(resources.GetObject("$this.Icon"), System.Drawing.Icon)
        Me.ImeMode = CType(resources.GetObject("$this.ImeMode"), System.Windows.Forms.ImeMode)
        Me.Location = CType(resources.GetObject("$this.Location"), System.Drawing.Point)
        Me.MaximizeBox = False
        Me.MaximumSize = CType(resources.GetObject("$this.MaximumSize"), System.Drawing.Size)
        Me.Menu = Me.mnuMain
        Me.MinimumSize = CType(resources.GetObject("$this.MinimumSize"), System.Drawing.Size)
        Me.Name = "frmMain"
        Me.RightToLeft = CType(resources.GetObject("$this.RightToLeft"), System.Windows.Forms.RightToLeft)
        Me.StartPosition = CType(resources.GetObject("$this.StartPosition"), System.Windows.Forms.FormStartPosition)
        Me.Text = resources.GetString("$this.Text")
        Me.Visible = CType(resources.GetObject("$this.Visible"), Boolean)
        Me.ResumeLayout(False)

    End Sub

#End Region

#Region " Standard Menu Code "
      ' <System.Diagnostics.DebuggerStepThrough()> has been added to some procedures since they are
      ' not the focus of the demo. Remove them if you wish to debug the procedures.
      ' This code simply shows the About form.
      <System.Diagnostics.DebuggerStepThrough()> Private Sub mnuAbout_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles mnuAbout.Click
            ' Open the About form in Dialog Mode
            Dim frm As New frmAbout()
            frm.ShowDialog(Me)
            frm.Dispose()
      End Sub

      ' This code will close the form.
      <System.Diagnostics.DebuggerStepThrough()> Private Sub mnuExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles mnuExit.Click
            ' Close the current form
            Me.Close()
      End Sub
#End Region

    ' This subroutine checks for available ports on the local machine. It does
    '   this by attempting to open ports 1 through 4.
    Private Sub btnCheckForPorts_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCheckForPorts.Click

        ' Check for Availability of each of the 4 Comm Ports, and
        '   place a check in the list box items that have openable ports.
        Dim i As Integer
        For i = 1 To 4
            WriteMessage("Testing COM" + i.ToString())
            If IsPortAvailable(i) Then
                ' Check the box for available ports.
                Me.clstPorts.SetItemChecked(i - 1, True)
            Else
                ' Uncheck the box for unavailable ports.
                Me.clstPorts.SetItemChecked(i - 1, False)
            End If
        Next
        ' Enable the Find Modems button.
        Me.btnCheckModems.Enabled = True
    End Sub

    ' This subroutine attempts to send an AT command to any active Comm Ports.
    '   If a response is returned then a usable modem has been detected
    '   on that port.
    Private Sub btnCheckModems_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCheckModems.Click
        Dim i As Integer
        For i = 0 To 3
            If Me.clstPorts.GetItemChecked(i) Then
                ' Item is checked so it MIGHT be a valid port.
                ' Test for validity.
                If IsPortAvailable(i + 1) Then
                    ' Check if port responds to an AT command.
                    If IsPortAModem(i + 1) Then
                        ' Set the class variables to the last modem found.
                        Me.m_IsModemFound = True
                        Me.m_ModemPort = i + 1
                        ' Write message to the user.
                        WriteMessage("Port " + (i + 1).ToString() + _
                            " is a responsive modem.")
                    Else
                        ' Write message to the user.
                        WriteMessage("Port " + (i + 1).ToString() + _
                            " is not a responsive modem.")
                    End If
                End If
            End If
        Next
        ' If a modem was found, enable the rest of the buttons, so the user
        '   can interact with the modem.
        If Me.m_IsModemFound Then
            Me.txtSelectedModem.Text = "Using Modem on COM" + _
                Me.m_ModemPort.ToString()
            Me.txtUserCommand.Enabled = True
            Me.btnSendATCommand.Enabled = True
            Me.btnSendUserCommand.Enabled = True
        End If
    End Sub


    ' This subroutine clears the TextBox.
    Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
        Me.txtStatus.Clear()
    End Sub


    ' This subroutine sends an AT command to the modem, and records its response.
    '   It depends on the timer to do the reading of the response.
    Private Sub btnSendATCommand_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSendATCommand.Click

        ' Always wrap up working with Comm Ports in exception handlers.
        Try
            ' Enable the timer.
            Me.tmrReadCommPort.Enabled = True
            ' Attempt to open the port.
            m_CommPort.Open(m_ModemPort, 115200, 8, Rs232.DataParity.Parity_None, _
                Rs232.DataStopBit.StopBit_1, 4096)

            ' Write an AT Command to the Port.
            m_CommPort.Write(Encoding.ASCII.GetBytes("AT" & Chr(13)))
            ' Sleep long enough for the modem to respond and the timer to fire.
            System.Threading.Thread.Sleep(200)
            Application.DoEvents()
            m_CommPort.Close()

        Catch ex As Exception
            ' Warn the user.
            MessageBox.Show("Unable to communicate with Modem")
        Finally
            ' Disable the timer.
            Me.tmrReadCommPort.Enabled = False
        End Try

    End Sub


    ' This subroutine sends a user specified command to the modem, and records its
    '   response. It depends on the timer to do the reading of the response.
    Private Sub btnSendUserCommand_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSendUserCommand.Click

        ' Always wrap up working with Comm Ports in exception handlers.
        Try
            ' Enable the timer.
            Me.tmrReadCommPort.Enabled = True
            ' Attempt to open the port.
            m_CommPort.Open(m_ModemPort, 115200, 8, Rs232.DataParity.Parity_None, Rs232.DataStopBit.StopBit_1, 4096)

            ' Write an user specified Command to the Port.
            m_CommPort.Write(Encoding.ASCII.GetBytes(Me.txtUserCommand.Text & Chr(13)))
            ' Sleep long enough for the modem to respond and the timer to fire.
            System.Threading.Thread.Sleep(200)
            Application.DoEvents()
            m_CommPort.Close()

        Catch ex As Exception
            ' Warn the user.
            MessageBox.Show("Unable to communicate with Modem")
        Finally
            ' Disable the timer.
            Me.tmrReadCommPort.Enabled = False
        End Try

    End Sub

    ' This subroutine is fired when the timer event is raised. It writes whatever
    '   is in the Comm Port buffer to the output window.
    Private Sub tmrReadCommPort_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrReadCommPort.Tick
        Try
            ' As long as there is information, read one byte at a time and
            '   output it.
            While (m_CommPort.Read(1) <> -1)
                ' Write the output to the screen.
                WriteMessage(Chr(m_CommPort.InputStream(0)), False)
            End While
        Catch exc As Exception
            ' An exception is raised when there is no information to read.
            '   Don't do anything here, just let the exception go.
        End Try

    End Sub


    ' This function checks to see if the port is a modem, by sending
    '   an AT command to the port. If the port responds, it is assumed to
    '   be a modem. The function returns a Boolean.
    Private Function IsPortAModem(ByVal port As Integer) As Boolean

        ' Always wrap up working with Comm Ports in exception handlers.
        Try
            ' Attempt to open the port.
            m_CommPort.Open(port, 115200, 8, Rs232.DataParity.Parity_None, _
                Rs232.DataStopBit.StopBit_1, 4096)

            ' Write an AT Command to the Port.
            m_CommPort.Write(Encoding.ASCII.GetBytes("AT" & Chr(13)))
            ' Sleep long enough for the modem to respond.
            System.Threading.Thread.Sleep(200)
            Application.DoEvents()
            ' Try to get info from the Comm Port.
            Try
                Dim b As Byte
                ' Try to read a single byte. If you get it, then assume
                '   that the port contains a modem. Clear the buffer before
                '   leaving.
                m_CommPort.Read(1)
                m_CommPort.ClearInputBuffer()
                m_CommPort.Close()
                Return True
            Catch exc As Exception
                ' Nothing to read from the Comm Port, so set to False
                m_CommPort.Close()
                Return False
            End Try
        Catch exc As Exception
            ' Port could not be opened or written to.
            Me.clstPorts.SetItemChecked(port - 1, False)
            MsgBox("Could not open port.", MsgBoxStyle.OKOnly, Me.Text)
            Return False
        End Try


    End Function

    ' This function attempts to open the passed Comm Port. If it is
    '   available, it returns True, else it returns False. To determine
    '   availability a Try-Catch block is used.
    Private Function IsPortAvailable(ByVal ComPort As Integer) As Boolean
        Try
            m_CommPort.Open(ComPort, 115200, 8, Rs232.DataParity.Parity_None, _
                Rs232.DataStopBit.StopBit_1, 4096)
            ' If it makes it to here, then the Comm Port is available.
            m_CommPort.Close()
            Return True
        Catch
            ' If it gets here, then the attempt to open the Comm Port
            '   was unsuccessful.
            Return False
        End Try
    End Function

    ' This subroutine writes a message to the txtStatus TextBox.
    Private Sub WriteMessage(ByVal message As String)
        Me.txtStatus.Text += message + vbCrLf
    End Sub

    ' This subroutine writes a message to the txtStatus TextBox and allows
    '   the line feed to be suppressed.
    Private Sub WriteMessage(ByVal message As String, ByVal linefeed As Boolean)
        Me.txtStatus.Text += message
        If linefeed Then
            Me.txtStatus.Text += vbCrLf
        End If
    End Sub

End Class
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