Control Frame Rate/excessive CPU load

If the CPU load (you can read this from the front panel or web interface) is high (reading 2 or more) you may experience one or more of the following issues:

- Sluggish control response
- External control problems
- Problems connecting with Kiosk
- Slow deploy
- Spontaneous XDAB re-arbitrations
- NION restarts

There are a number of things that can cause this.  Typically it is associated with projects that have a lot of control activity, lots of meters, python scripts, etc. 

There is one simple thing you can try that will often clear this up.  Decrease the Control Frame Rate (this is a project property found in File/Project Properties).  By default new projects are created with this set to 30.  This means the controls are processed 30 times a second, or roughly every 30ms.  If you reduce this to 10, you decrease the control processing the NION needs to do by a factor of 3.  This does reduce the control response time (to roughly 100ms) but for most applications this is plenty fast.  You should see a dramatic change in the CPU load figure, and in many cases this eliminates the issues listed above.

We plan on changing the default for this value to 10 in the next release of NWare.  Note that this will not affect any existing projects, only new ones.  Note also that if this works for you, and your workflow is to start from a "standard" project you've created, you might want to change this in your standard project so all future projects will have this set automatically.

Because we intend to change the default in the next release of NWare, we would appreciate feedback on how this works (or doesn't work) for you.