GPIB addressses not displayed in VISA control

[amose]

Hi
I am using LV8.2 and many of the vi's I have are written in LV6.1.
when I open one of my old vi's in many cases the VISA address control does not show any of the devices present on the system. all I get is a "refresh" message. after this happens I can not in any way use this VI to communicate to the devices.
the only temporary solution for this is to close LV. reopen it and open a new blank VI. then i place a VISA address control and select a device from the list. only then I open the original VI and then the VISA addresses appear.
does anyone know a solution for this problem,
thanks
amose

[Anna_M]

Hi amose,

So if you select the "Refresh" option, no new VISA resources are detected?  But if you place a new VISA Resource block on the block diagram, everything is appropriately detected - is that correct? 

I am curious - were your older vi's written on the same computer that you are now running with LabVIEW 8.2?  Does this behavior occur only the first time you open these older vi's in LabVIEW 8.2, or does it happen everytime you try to open the vi?

[amose]

hi Anna,
not exactly.
if the first VI i open  is one of the old ones, no matter what i do later, all the Visa resources contain the refresh only. (as long as Lv is open) this happens every time I open them.
but, if i open a new VI or an empty VI and press at least once to see my devices, from now on as long as LV is open i see the devices in the old VIs again.
this happens both with my Vis and also with VIs I get from the the devices manufacturer.
regards
amose

[Anna_M]

Hi amose,

That's interesting because it sounds like when you open a new VI, the VISA resource list is refreshed for any programs you open from then on.  But, it sounds like when you open your "old" vi's first, and select "refresh" from the pull-down menu nothing happens (the list isn't repopulated with your VISA resources).  Is that correct?  I assume that all of the VISA resources show up properly in MAX on this computer?

[amose]

all true.

[Anna_M]

Hi amose,

That is bizarre.. I'll see if I can reproduce the behavior here.  And to clarify - what is the bus type of the VISA resources in question for you?  Are they built-in serial ports, instruments on a GPIB interface, USB devices?  Thanks!

[amose]

hi anna
both regular internal ports and GPIB ports (through an NI GPIB PCI card)
thanks again
amose

[Anna_M]

Hi amose,

So in an effort to reproduce this behavior, I created a simple VISA program in LabVIEW 6.1, then I moved it to my computer & opened it in LabVIEW 8.2.  When I used the VISA Resource pull-down menu, everything was populated properly, so I did not see the problem that you described.  Have you seen this on multiple computers?  Or are you working with executables or some variation of the test I performed here?

[amose]

hi Anna
when I see this problem it goes on in the executable as well.
this problem( when it occurs) happens on both stations i have.(both 8.2)
i am attaching a VI that does this problem( i do not have the original 6.1 version)

thanks
Amos

[Anna_M]

Hi amose,

I tested your code out on my computer here, and opening the vi up, and selecting the VISA pull-down menu, it was automatically populated with COM1 and LPT1, which are the two VISA resources on my computer.  So, I am not seeing this same behavior you describe.  Have you tried this on different computers?  Also, let's make sure you have the most recent version of NI-VISA: https://www.ni.com/en/support/downloads/drivers/download.ni-visa.html.