Hy!
I'm newbie to VB 2005 and I'm trying to read value from a device
driver, as I used in VB6 with CreateFile and DeveiceIoControl. I get a
correct driver handle with CreateFile but I can't read values with
ReadFile, as reported in this URL
http://support.microsoft.com/default.aspx?scid=kb;en-us;823179&Product=vb6

I tried with ReadFile with the following code lines:

       Try
            Success = ReadFile(hSerialPort, Buffer, BytesWritten,
BytesRead, IntPtr.Zero)
            If Success = False Then
                Throw New CommException("Unable to read from driver")
            End If
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        Finally
        End Try

but  I couldn't get values from device driver 'cause I get an exception
("Unable to
read from driver").

Is it better DeviceIoControl? What am I doing wrong?

Thanks for your replies.

What does System.Runtime.InteropServices.Marshal.GetLastWin32Error()
return after the ReadFile call?


Mattias

Mattias Sjögren ha scritto:

It returns 6. What does it mean?

Thanks


Show quoteHide quote

It means "The handle is invalid". Have you verified that CreateFile
really returns a valid handle? What's the type of hSerialPort?


Mattias

Mattias Sjögren ha scritto:

No, it returned an invalid handle and I've already fixed the code for
it, but I still haven't found a solution for ReadFile 'cause I get
"LastWin32Error 1: Incorrect function".

        Try
            Success = ReadFile(hCVxD, Buffer, BytesWritten, BytesRead,
IntPtr.Zero)
            If Success = False Then
                Throw New CommException("Unable to read from driver")
            Else
                TextBox3.Text = CStr(BytesRead)
            End If
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub

What am I doing wrong?
According .NET, which is better: DeviceIoControl, as in VB6, or
ReadFile?

Thanks for your replies.

Is this a serial port device?  If so, why not use System.IO.Ports?

Personally, I want more information about what it is that you are REALLY
trying to do before suggesting what might be the problem/solution.

Dick

Dick Grier ha scritto:

Show quoteHide quoteI'm trying to read values from an ISA card.

Thanks for your attention

ADO.net + MS Access = performance issues
VB.NET Structures and Union Help.
how to group similar events?
2nd Post: Problem adding events to controls created at run-time
KeyUp + KeyDown Event Handler
Problems with ByRef parameters
Copying files across network
String vs. Stringbuilder speed parsing questio
System.IO.FileSystemWatcher is missing alot of files.
continue debugging without interrupting