VISA Ref control freezes LV7 for >50 secs

[LuI]

Hi,

I know this has been asked for and I know there is the chance to hide VISEW Ref controls to avoid this delay, but during tetst and devellopment this is impractical.

I have a test system for medical devices. This one has besides some 6 real VISA devices also >25 serial ports.
If I open a VI that has a visibel VISA ref (control or constant) it takes literally >50 seconds to get this operabel. Not only this VI is inoperabel - the whole LabVIEW is frozen! This is frustrating!

Any known way to avoid this or to shorten this period?
Dan M, are you reading this?

TIA and
Greetings from Germany!

[Alan_L]

Lul,

When it boils right down to it, the VISA resource name is a string. This means that if you know the VISA name / alias of your instrument (eg. COM1 or GPIB0::2::INSTR), you can wire a string constant / control with the appropriate value into your VISA Open or VISA Write. This technique will avoid the delay involved when VISA attempts to discover all of the ports available on your computer while populating the resource name list.

Thanks!!

Alan
Applications Engineer
National Instruments

[LuI]

Alan,

very good hint - I'll try it out.

Until now I had often used a technique where I had such VISA Ref ctrl invisibel and had informed the user bevore switching it to visibel. This did not avaoid LV hanging for that extended period, but the user had known this might be unavoidabel. But during devellopment this is simply frustrating.
Your devellopers should search for a better solution. It was acceptabel (well, not really) if the VI in questrion would hang until the VISA Ref Ctrl list is populated. BUT NOT THE WHOLE LV! Bring this to another thread or whatever, please.
Thanx for the response!
Greetings from Germany -
Uwe