Hi Moshik,
That's something I haven't tried yet. Presently, I'm doing the same thing as you - closing the application after I finish using it and re-opening later. In doing so, I take a 20 second hit while the software starts every time I use it.
Here's something that may warrant investigating - If you use the front panel Mode key, an instance of the VSA stays running in the background. There may be a "Mode" command through DCOM. In theory, this should allow you to switch back to the VSA quickly. The downside is you may end up doing all your spectrum analyzer commands through DCOM too. Also, if you're using a floating license, switching through the Mode key (and I assume a Mode command) ties up the license so it can't be used by another machine.
There is a "quick and dirty" way to do what you want - I assume you're passing a reference to the VSA application around in your program somehow. Try to do something simple with the existing reference (read the center freq. for example). If it fails, then start a new instance of the VSA application and retry. If you're able to do your operation with the new reference (read start freq in this example), then pass the new reference out. If it still fails with the new instance, then pass the failure to Error Out. You could even refine this to test for a specific error code that's passed when the reference isn't valid. One thing you'd probably need to do would be to change the timeout to something like 2 seconds before you tried to read the start freq., otherwise you could end up sitting there for some time waiting for the the read routine to fail.
Let me know how you make out.
Good Luck,
Doug
