VISA write from LabView DLL

[Mark CSULA]

I created a VI that is able to control a USB device by writing commands with VISA.

Now, I need to execute these write commands from a C program.

I built a DLL out of the VI in labview.

But it doesn't seem to be executing when I call it in the code.

I've verified that I get to the point in the code where the DLL is called.

The program also seems to succesfully be able to determine the USB device ID.

Are there any subtle steps I might be missing?

Thanks!

[Pcorcs]

Hello Mark,

Is the DLL designed to be debuggable? Is there an error that occurs, or just a hung point in the code? I presume the code was tested and is working out of LabVIEW, and has ceased to work in the DLL form? Can a simplified C program call VISA directly without error? Are any function parameters path dependent? Have you ensured that the function prototypes generated by LabVIEW match you C function calls?

I appreciate your time working through these questions. Perhaps, compiling a very simplified VISA call in a single function DLL may isolate if VISA is the source, or some other code parameter. 

Please post back any further questions or information regarding the system.