Performance concerns about NSVs in large RT applications

[JKSH]

Hello,

The end of http://www.ni.com/white-paper/12176/en says "...misuse of Shared Variables in a LabVIEW Real-Time application can result in poor machine performance.... Typical misuses include using too many Shared Variables.... In applications deployed to small Real-Time targets such as Compact RIO or Compact FieldPoint, no more than 25 variables should be used."

Does this apply to network-published I/O Aliases as well? I was planning to have ~100 I/O Aliases (cRIO-9082 + 2x NI-9144), exposed to a Windows PC for DSC logging and/or alarming -- would that be a problem?)

[Haagen-Dazs · Accepted solution]

Hi JKSH,

Using the 9082 cRIO you should be more than ok to host that many I/O Aliases. Depending on the controller you could run into issues where there are memory limitations on the controller. However, that controller should have more than enough memory to support that many variables. The best way to get an idea of how the variables are affecting your system is to monitor the CPU and memory usage in MAX. I would also recommend only installing the necessary software onto the cRIO and not everything that is possible. I hope this helps and if you have any more questions please let me know.

[JKSH]

Thanks Patrick, that's great to know.

[Haagen-Dazs]

Hi JKSH,

I wanted to correct myself in the last post. To monitor the memory and CPU usage you should use the NI Distributed System Manager and not Measurement and Automation Explorer (MAX). Sorry for the confusion.

[JKSH]

Hi Patrick,

Thanks for clarifying. No damage done 🙂