labview freezes when VISA comm address entered

[JLPD]

Hello all,

I've just started using labview: we're setting up a cold molecule experiment and we intend to use it to control our oscilloscope and pulse/delay generator.  Among a long list of problems, labview has started crashing.  I had downloaded the Lecroy Waverunner Series library from NI, and until yesterday the software itself was working fine (my inability to use it we shall gloss over).  As of yesterday, however, whenever I attempt to enter a VISA comm address in the relevant boxes of the example vi's, labview freezes.  This is not on execution, merely upon typing the first digit of the VICP address.  According to task manager, labview doesn't do anything, or at any rate not using any CPU and its memory usage doesn't increase.  It just sits there, and can only be gotten rid of by restarting the computer.  It has been working happily for two weeks, and I haven't changed any part of its installation.  Other parts of the front panel can be fiddled with quite happily.  Does anyone know what this could be and how I could fix it, or would I be better off just reinstalling the blighter?  I am using labview 8.5, NI-VISA 4.4.1, and have Lecroy's VICP passport installed.

Thank you.

[Jeremy_T]

Hi JLPD

I've done some research into finding out why this problem has occured and have managed to come up with a possible workaround. In essence, a VISA resource name is a string, and so it is possible to use a string as a substitute for the VISA resource name. You should ensure that the format of the string is GPIBx::y::INSTR, where x is the GPIB Interface Number, and y is the Primary Address. By doing so, you should be able to perform basic VISA write and read functions, as well as other functions such as the lock asynchronous and unlock.

Also, here are a couple of links to other forum threads that feature similar problems from other LabVIEW users:

http://forums.ni.com/ni/board/message?board.id=170&message.id=49032&requireLogin=False

http://forums.ni.com/ni/board/message?board.id=140&message.id=6327&requireLogin=False

http://forums.ni.com/ni/board/message?board.id=140&message.id=14630&requireLogin=False

As is suggested in a couple of the threads, it may be a good idea to run NI-SPY to check whether LabVIEW has truly frozen or whether it is just taking a long time to process.

I hope this helps, best regards

[alanjb]

Hi JPLD,

Alan from LeCroy Tech Support here...   That's an unusual problem; I haven't heard about it from any of my customers.  Since you're using the TCP/IP interface via the VICP Passport to communicate with the scope, using a GPIB-style VISA resource string isn't going to be of much help. Nonetheless, I wonder if this also causes a hang.  You might want to play with the VISA resource "I/O Name Filtering"... Right-click on the resource name control to find it in the drop-down menu.  Maybe if you change the options within the I/O filtering, you'll end up doing an "end-run" around the bug that causes the hang...  Also. maybe reinstalling VISA and/or LabVIEW will help (I don't think that it would hurt!)

Best Regards,

Alan Blankman

[JLPD]

Thank you both, gentlemen.  I have in fact deleted the instrument library and downloaded a replacement, and it seems to be working fine - I should probably have done that in the first place!  I shall, however, make a note of your advice in case the problem should recur.  Thank you again.

[alanjb]

Hi JPLD,

What did you delete exactly?  The entire instr.lib folder, or something else?

Thanks,

Alan

[JLPD]

Hello Alan,

I'm sorry, that was a little ambiguous.  I have not deleted the whole instr.lib folder, but rather the LeCroy Waverunner Series folder from the instr.lib folder; my new copy of the LeCroy library is now functioning fine.  Interestingly, I earlier on today got the same error with a vi of my own construction designed to communicate not with the LeCroy scope but with a Berkeley Nucleonics pulse/delay generator.  This time, though, the problem was not recurrent and it is working fine now, though I can't tell you what I did that made it better: whether it was restarting the computer, changing the visa comm control to a constant, or noticing that the baud rate of the pulse generator was wrong and correcting it.