LabVIEW
VISA Find Resource primitive runs much slower on OS X compared to Windows
Hello Everyone,
We have a large application that is built with LabVIEW 2014 64-bit that calls the "VISA Find Resource" primitive in a While Loop as the basis for automatic hardware discovery.
On Windows, everything works fine. However, we just started using LabVIEW for OS X to build our application for Mac and I noticed that the "VISA Find Resource" primitive executes about 10 times slower. This causes a handful of issues in our application since things were coded around this assumption that this primitive would execute very quickly.
I wrote a VI in LabVIEW 2014 64-bit that I've run on both a Windows 7 64-bit machine and several Mac computers running Yosemite. The VI runs this primitive in a while loop which stops after the user-defined number of iterations have been performed and gathers timing statistics. I've attached this VI for reference. Below are the screenshots of the VI after running them on OS X Yosemite vs Windows 7 with the VISA Find Resources running 10,000 times.
As you can see, the front panel displays the current iteration number (Loops), the current millisecond measurement during a loop, the mean millisecond measurement for the number of loops so far, the standard deviation, and variance. What I can see is that the standard deviation and variance are very similar across both platforms. It's just that for some reason the VISA Find Resources primitive runs slower on OS X Yosemite at about 6.5ms per execution vs Windows at 0.73ms per execution. I've also run this VI on a Mac Mini running Mavericks with nearly identical results (mean time of 6.5ms). As I mentioned before, this primitive taking about 10 times longer to execute really hinders the performance of our application.
Is this a known issue for LabVIEW or VISA for OS X? Is there any way to get performance comparable to Windows on OS X?
Thanks!
There is one serious difference between these two examples that could at least partially cause some of that difference. On the Mac you have 6 or so resources that satisfy the request, on Windows none. It's not exactly a fair comparison that way.
VISA Find Resource on Windows can be slow too, if there are quite some VISA resources to scan. In fact I consider 6 ms runtime for VISA Find Resource a damn fast execution time. I had in the past easily execution times of several seconds when searching for ASRL (serial) resources. And that was on Windows.
