Device Driver in VB 2005

  • Thread starter Thread starter Fla
  • Start date Start date
F

Fla

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

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


Mattias
 
Mattias Sjögren ha scritto:
What does System.Runtime.InteropServices.Marshal.GetLastWin32Error()
return after the ReadFile call?
Click to expand...

It returns 6. What does it mean?

Thanks
 
It returns 6. What does it mean?

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


Mattias
Click to expand...

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

--
Richard Grier, MVP
Hard & Software
Author of Visual Basic Programmer's Guide to Serial Communications, Fourth
Edition, ISBN 1-890422-28-2, Mabry Publishing (391 pages, includes CD-ROM).
July 2004.
See www.hardandsoftware.net for details and contact information.
 
Dick Grier ha scritto:
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

--
Richard Grier, MVP
Hard & Software
Author of Visual Basic Programmer's Guide to Serial Communications, Fourth
Edition, ISBN 1-890422-28-2, Mabry Publishing (391 pages, includes CD-ROM).
July 2004.
See www.hardandsoftware.net for details and contact information.
Click to expand...

I'm trying to read values from an ISA card.

Thanks for your attention
 
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