Can LabVIEW call a function from a .sys file or is LabVIEW limited to dll access?

[ottomatic]

My vendor has sent me a .sys file with functions accessing their hardware.  Can i call these function from labview directly or do I have to wrapper the .sys with a dll?

[rolfk]

Well a sys file is a kernel device driver. LabVIEW does not have any direct way of accessing such a driver. The way kernel drivers are accessed is usually through a DLL which makes calls to WinAPI functions such as CreateFile(), ReadFile(), WriteFile(), CloseHandle() and DeviceIORequest(). Since these WinAPI calls are basically just DLL calls too, you could theoretically use the Call Library Node to call them and access the kernel device driver in such a way.

However for any kernel device driver with more than one or two device driver calls, it will certainly be easier in terms of development, debugging and maintenance of the code, to write actually a dedicated DLL in C/C++ for this device driver and access that DLL from LabVIEW, especially if you consider the LabVIEW datatype limitations when designing the DLL interface (Basically this same DLL can then be called from any other Windows development environment, be it Visual Basic (similar datatype limitation as LabVIEW), Delphi, (Visual) C, LabVIEW or also various scripting environments like Python and Lua.

Some of the necessary WindAPI calls are rather involved and pose quite a bit of trouble to get the parameter data right in LabVIEw.