Question about usb in labview

Question

I am currently doing a project about designing standalone data acquisition module with USB 2.0 interface.
For the hardware, a USB FIFO chip(FT245BM) is used to communicate with PC via USB with the driver DLL provided by the manufacturer (FTDI).
I want to use labview (version 7.0)to develop a data logging software and I learned that the functions in the DLL could be called by the 'library call function node' in labview.
My question is:
1.Apart from labview, do I need to intall Measurement and Automation Exploere to configure the hardware before I use it in the labview?
2. I noticed that the type of call in labview should be configured as either 'c' or 'stdcall'. My knowledge about C/C++ is poor, could someone explain them in
detail and which one shall I choose?
3.I heard that not all the DLLs could be used in labview (due to the problem of different format???). I don't quite understand about this. Could anyone be kind to explain about this as well?
Many thanks!!!

Answer 1

Xiaohui wrote:
> I am currently doing a project about designing standalone data
> acquisition module with USB 2.0 interface.
>
> For the hardware, a USB FIFO chip(FT245BM) is used to communicate with
> PC via USB with the driver DLL provided by the manufacturer (FTDI).
>
> I want to use labview (version 7.0)to develop a data logging software
> and I learned that the functions in the DLL could be called by the
> 'library call function node' in labview.
I assume your chip comes with a Software Development Kit (SDK) with a
ready made driver. This driver consists of a kernel mode driver and the
user mode shared library (DLL). LabVIEWs call library node can be used
to call such user mode DLLs.
> My question is:
> 1.Apart from labview, do I need to intall Measurement and Automation
> Exploere to configure the hardware before I use it in the labview?
Very unlikely, as the driver which comes with your SDK for the chip will
be not configurable at all in Measurement & Automation Explorer (MAX).
MAX really is only to configure National Instruments hardware devices
and to some lesser extend external measurement devices connected through
the GPIB, VXI and PXI bus.
The NI-VISA driver 3.0 which comes in LabVIEW 7.0 can also directly
communicate with the raw USB interface of some devices. If you want to
use that interface you would NOT install the driver for that device and
would configure that device in MAX instead. You do need to know the
manufacturer ID and Device ID of your USB chip for that. Also the
programming in LabVIEW through the VISA functions is possible but it is
not very simple and completely dependant on the implemenation of the USB
communication by that chip. There are some documents on Developer
Exchange and also some discussion topics here on this forum about VISA
and USB communication.
> 2. I noticed that the type of call in labview should be configured as
> either 'c' or 'stdcall'. My knowledge about C/C++ is poor, could
> someone explain them in detail and which one shall I choose?
Most Windows DLLs use stdcall but this is not a must. If you get it
wrong you will simply crash LabVIEW. The documentation or if that
doesn't work the header file which comes with the DLL should give you
this information, although for the header file you need to know a little
C to understand where it shows this.
> 3.I heard that not all the DLLs could be used in labview (due to the
> problem of different format???). I don't quite understand about this.
> Could anyone be kind to explain about this as well?
Windows DLLs should be fairly standard. The only problem could be .Net
assemblies which are not really DLLs but a complete archive of DLL's
documentations, certificates and, and, and!
It's still very unlikely that a device would come with a .Net assembly
instead of a simple DLL with the according API.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions