Knowledge Base

BUG: VBCE: Unable to Send an Array Using the MSCEComm Control

Article ID: 271302

Article Last Modified on 8/19/2005

APPLIES TO

Microsoft eMbedded Visual Basic 3.0
Microsoft Windows CE Toolkit for Visual Basic 6.0

This article was previously published under Q271302

SYMPTOMS

In a Windows CE Toolkit for Visual Basic (VBCE) 6.0 or an eMbedded Visual Basic (eVB) 3.0 project that uses the MSCEComm control, when you attempt to send an array from the device, the data is not transmitted and there are no errors.

RESOLUTION

To work around this problem, add the following code to Form1 in the Visual Basic for CE sample that is shown in the "Steps to Reproduce Behavior" section:

Declare Function WriteFileL Lib "Coredll" Alias "WriteFile" _
    (ByVal hFile As Long, lpBuffer As Byte, ByVal nNumberOfBytesToWrite As Long, _
    lpNumberOfBytesWritten As Long, ByVal lpOverlapped As Long) As Long

Public Sub SendArrayData(ByVal hCommID As Long, baData)
    Dim i, lRet, iWrite
    For i = LBound(baData) To UBound(baData)
        lRet = WriteFileL(hCommID, baData(i), 1, iWrite, 0)
    Next
End Sub

Next replace the Command2_Click event code, in the same project, with the following:

Private Sub Command2_Click()
    Dim bTemp(29) As Byte, y As Integer

    For y = 0 To 29
        bTemp(y) = y
    Next y

    SendArrayData Comm1.CommID, bTemp
End Sub

When you run both of these projects and select Receive Array, you should see that when you click Send Array, the textbox displays the numbers 0 through 29.

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

MORE INFORMATION

Steps to Reproduce Behavior

You will need to create two projects, one using Windows CE Toolkit for Visual Basic 6.0 or eMbedded Visual Basic 3.0, and the other using Microsoft Visual Basic 6.0.

Visual Basic for CE Project

Start VBCE 6.0 or eVB 3.0.
Create a new Windows CE HPC PRO project. Form1 is created by default.
On the Project menu, click Components, and then click to add the Microsoft CE Comm Control 3.0.
Add a text box, two command buttons, two option buttons, and a Comm control to Form1.

Paste the following code to Form1:

Option Explicit
Dim CRflag As Boolean, UseString As String, bText As Boolean
   
Private Sub Comm1_OnComm()
    Select Case Comm1.CommEvent
        Case comEvReceive
            If bText Then
                ReceiveText (Comm1.Input)
            Else
                ReceiveArray (Comm1.Input)
            End If
    End Select
End Sub

Private Sub Command1_Click()
    Comm1.Output = "Text works correctly"
End Sub

Private Sub Command2_Click()
    Dim bTemp(29) As Byte, y As Integer
    
    For y = 0 To 29
        bTemp(y) = y
    Next y
    
    Comm1.Output = bTemp
End Sub

Private Sub Form_Load()
    Option1.Caption = "Receive Text"
    Option2.Caption = "Receive Array"
    Option1.Value = True
    
    Command1.Caption = "Send Text"
    Command2.Caption = "Send Array"

    Comm1.CommPort = 1
    Comm1.RThreshold = 1
    Comm1.Handshaking = comRTS
    Comm1.PortOpen = True
End Sub

Private Sub Form_Unload(Cancel As Integer)
    If Comm1.PortOpen Then Comm1.PortOpen = False
End Sub

Private Sub Option1_Click()
    bText = True
    Text1.Text = ""
    Comm1.InputMode = comInputModeText
End Sub

Private Sub Option2_Click()
    bText = False
    Text1.Text = ""
    Comm1.InputMode = comInputModeBinary
End Sub

Private Sub ReceiveText(ByVal InString As String)
   Dim y As String
   Dim x As Integer

   For x = 1 To (Len(InString) + 1)
      y = Mid(InString, x, 1)
      If y = Chr(13) Then
         CRflag = True
         y = ""
         UseString = Trim(UseString)
         UseString = ""
      End If
      If y = Chr(10) Then
         y = ""
         CRflag = False
      End If
      If CRflag = False Then
         UseString = UseString & y
         Text1.SelStart = Len(Text1.Text)
         Text1.SelText = y
      End If
   Next x
End Sub

Private Sub ReceiveArray(ByVal inArray As Variant)
    Dim lCount As Long
    
    For lCount = 0 To UBound(inArray)
        Text1.Text = Text1.Text & CStr(inArray(lCount)) & " "
    Next
End Sub

Compile and then save the project.
Create a setup package using the Application Install Wizard, and deploy the package to the device.

Visual Basic 6.0 Project

Start Visual Basic 6.0.
Create a new Standard EXE project. Form1 is created by default.
On the Project menu, click Components, and then click to add the Microsoft Comm Control 6.0.
Add a text box, two command buttons, two option buttons, and a Comm control to Form1.

Paste the following code to Form1:

Option Explicit
Dim bText As Boolean

Private Sub Command1_Click()
    MSComm1.Output = "Text works correctly"
End Sub

Private Sub Command2_Click()
    Dim bTemp(29) As Byte, y As Integer
    
    For y = 0 To 29
        bTemp(y) = y
    Next y
    
    MSComm1.Output = bTemp
End Sub

Private Sub Form_Load()
    Command1.Caption = "Send Text"
    Command2.Caption = "Send Array"
        
    MSComm1.CommPort = 1
    MSComm1.RThreshold = 1
    MSComm1.Handshaking = comRTS
    MSComm1.PortOpen = True
    
    Option1.Caption = "Receive Text"
    Option2.Caption = "Receive Array"
    Option1.Value = True
End Sub

Private Sub Form_Unload(Cancel As Integer)
    If MSComm1.PortOpen Then MSComm1.PortOpen = False
End Sub

Private Sub MSComm1_OnComm()
    Select Case MSComm1.CommEvent
        Case comEvReceive
            If bText Then
                ReceiveText (MSComm1.Input)
            Else
                ReceiveArray (MSComm1.Input)
            End If
    End Select
End Sub

Private Sub Option1_Click()
    bText = True
    Text1.Text = ""
    MSComm1.InputMode = comInputModeText
End Sub

Private Sub Option2_Click()
    bText = False
    Text1.Text = ""
    MSComm1.InputMode = comInputModeBinary
End Sub

Private Sub ReceiveText(ByVal InString As String)
   Dim y As String
   Dim x As Integer
' These are declared Static so that they will persist between
' function calls:
   Static CRflag As Boolean
   Static UseString As String

   For x = 1 To (Len(InString) + 1)
      y = Mid$(InString, x, 1)
      If y = Chr$(13) Then
         CRflag = True
         y = ""
         UseString = Trim(UseString)
         UseString = ""
      End If
      If y = Chr$(10) Then
         y = ""
         CRflag = False
      End If
      If CRflag = False Then
         UseString = UseString & y
         Text1.SelStart = Len(Text1.Text)
         Text1.SelText = y
      End If
   Next x
End Sub

Private Sub ReceiveArray(ByVal inArray As Variant)
    Dim lCount As Long
    
    For lCount = 0 To UBound(inArray)
        Text1.Text = Text1.Text & CStr(inArray(lCount)) & " "
    Next
End Sub

After you have completed both projects and deployed the application to the device, perform the following steps:

Go to the Connection Settings of ActiveSync and uncheck Allow serial cable or infrared connection to this COM port.
Start the application on the device and run the Visual Basic project in the development environment.
On the device, click Send Text. You should see "Text works correctly" displayed in the Visual Basic application. This works correctly in the other direction as well.
Select Receive Array on both applications, and click Send Array on the device. You will see that nothing is displayed in the Visual Basic application. If you click Send Array on the Visual Basic application, you will see the numbers 0 through 29 displayed on the device.

Additional query words: wce evb vbce

Keywords: kbbug kbpending KB271302

Microsoft KB Archive/271302

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