This answer, while correct, doesn't address the issue of some VISA classes and how Labview addresses open VISA sessions. It is quite correct concerning the listing of available resources, that is not the nature of my problem. The heart of the matter is the Open VISA sessions and how they are returned by the "Open VISA sessions.vi" vi in the vi.lib utilities. Also, the VISA reference control does, as you say, display currently available resources (for some classes), but it also displays currently open sessions below a dividing line for those resources not usually displayed.
The best example of this is for the TCP/IP class. Resources of this class are not displayed unless a session for them has been opened.
I have written and compiled an executable tha
t opens a VISA session for a TCP/IP resource. After opening it, the session is displayed in the executable's VISA resource control below a dividing line that separates it from the available serial and GPIB resources. If, however, I have an uncompiled VI with a VISA control open in the development environment at the same time, the open session is not displayed in that VI's resource control. If I run the compiled executable as an uncompiled VI in the development environment along with other VI's containing VISA resource controls, the open TCP/IP session is displayed in all VI's. The same holds true for the "Open VI sessions.vi". Sessions opened by compiled VI's are not returned by this subVI when it is run from outside the executable.
As I stated before, it appears the executable creates its own separate memory space for listing open VISA sessions.
I would like to create a small executable that logs in to TCP/IP resources and makes those sessions available to other VI's that ar
e either uncompiled and running in the devel environment, or are running as separate executables.
Thanks for your comments
Steve