vb6 multithread runs 21 times then stops and errors
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    Join Date
    Sep 2013
    Posts
    3

    vb6 multithread runs 21 times then stops and errors

    Hi,
    I have a project that has to read the usb port all the time and look at the data to parse it out and put some strings in a file.
    The following code will read the usb port and put the data into a circular buffer so that the top level application can read the data and then process it.
    This code seems to run 21 times before it just exits.
    I do not know what would cause such behavior,
    Can anyone offer any suggestions?
    Thanks,
    Martin

    Code:
    Public Sub WaitForUsbRet()
    Dim EventObject As Long
    Dim Result As Long
    Dim res2 As Integer
    Dim Security As SECURITY_ATTRIBUTES
    Dim RecBuffer(65) As Byte
    Dim rdNum As Long
    Dim i As Integer
    Dim res3 As Long
    res2 = 1
    
        Security.lpSecurityDescriptor = 0
        Security.bInheritHandle = CInt(True)
        Security.nLength = Len(Security)
            
        EventObject = CreateEvent(Security, CInt(True), CInt(False), "rdUsb")
        HIDOverlapped.Offset = 0
        HIDOverlapped.OffsetHigh = 0
        HIDOverlapped.hEvent = EventObject
    
        Do
            Form1.ShpStatus.BackColor = Form1.ShpStatus.BackColor + 1
            DoEvents
            RecBuffer(4) = 0
            RecBuffer(5) = 0
            Result = ReadFile _
            (HIDHandle, _
            RecBuffer(0), _
            CLng(Capabilities.InputReportByteLength), _
            rdNum, _
            HIDOverlapped)
    
            Form1.lstBoxRec.AddItem "Res=" & Result & " rdnum=" & rdNum & " hid=" & HIDOverlapped.Internal
    
            Result = WaitForSingleObject(EventObject, 500)
            
            Form1.lstBoxRec.AddItem "Res2=" & Result & " err=" & GetLastError & " hid=" & HIDOverlapped.Internal
    
            Select Case Result
                Case WAIT_TIMEOUT
                ' Timeout error.
                    Form1.lstBoxRec.AddItem "Out"
                    CancelIo (ReadHandle)
                    Form1.devStatus = RET_USBDEVREVTOOLOW
                    DoEvents
                Case WAIT_FAILED Or WAIT_ABANDONED
                    Form1.lstBoxRec.AddItem "FAIL"
                    DoEvents
                Case WAIT_OBJECT_0
        '        ' Success
        '        ' Use the report data.
                    rdNum = (RecBuffer(4) + 5)
                    If rdNum > 65 Then rdNum = 65
                   If (rdNum > 5) Then
                        For i = 1 To rdNum
                           Form1.putInCircBuff (RecBuffer(i))
                        Next i
                    End If
                    Form1.lstBoxRec.ListIndex = Form1.lstBoxRec.ListCount - 1
                    If (rdNum > 0) Then Form1.tmrCommHndl.Enabled = True
                    DoEvents
                Case Else
                    Form1.lstBoxRec.AddItem "Else"
                    CancelIo (ReadHandle)
                    Form1.devStatus = RET_USBDEVREVTOOLOW
            End Select
            res3 = ResetEvent(EventObject)
        Loop Until res2 = 0
    End Sub
    Last edited by GremlinSA; September 19th, 2013 at 01:46 AM. Reason: added code tags..

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