Remote Front Panel Problems and Best Practices

[xkenneth]

All,

Problems

I'm currently attempting to host a Remote Front Panel from a cRIO 9073. The intent of the front panel is to control and configure the services running on the cRIO. Currently I've been experiencing quite a few problems getting this to operate smoothly.

These are the problems I'm currently experiencing.

* Front panel takes a very long time to load (~45 Seconds).

* On close the front panel may reset the cRIO.

* Front panel may cause excessive CPU usage.

* Plugin has problems in Firefox.

I'm fairly sure that I've installed all of the Latest NI software (I'm using LV 2009f2)

I currently cannot post the code as it's proprietary.

Currently the front panel consists of two timed loops one running at 500ms intervals and the other running at 1000ms intervals. The GUI is basically a tab control and on the heaviest tab contains about 15 buttons.

Questions

Is it not possible to use event structures in embedded LabVIEW? So far I've had to code my own event loop to handle all the events I wish to process on the remote front panel, and I feel this might be causing a problem.

Is the sort of functionality I'm trying to achieve acceptable in Web Front Panels?

It seems that the reason it takes very long for the VIs to load is that the VI Front Panel Server must fire up. Is there a way to make this or whatever the component is that handles it fire ahead of time?

Thanks for your time, I look forward to discussing this.

Regards,

Ken

[xkenneth]

Opening the remote front panel, and then refreshing or attempting to access the URL again will result in reloading the front panel and then a reboot shortly thereafter. I have my code configured to output that it's going down for reboot via the serial port, and I see no output, which leads me to think something else is rebooting my code. Also of note is that when it loads the front panel the second time the CPU usage goes through the roof.

[xkenneth]

I also just saw this knowdledge base.

http://digital.ni.com/public.nsf/allkb/B892632F7C1B8EE786257323007E988D

My intent is to have the cRIO operating in an isolated environment. If for some reason the call to remote front panel plugin or the remote front panel server is trying to contact ni.com or any other site, it's always going fail.

Is the remote front panel functionality attempting to contact external web addresses?

If so is there anything I can do about it? Reducing the DNS timeout? Setting them to a dummy address in hosts (I don't know what the similar functionality is on Windows.)

[xkenneth]

I've determined that no DNS queries are being made (via wireshark) to www.ni.com or any other URL when a remote front panel is loaded.

One things that's interesting is that if I create a very simple VI with a simple front panel it takes just as long to load and behaves just as badly, although it requires far less CPU useage (about 15% overall vs 35% on the 9073.)

[Kristen_K.]

Hi Ken,

Is this a remote front panel for a real-time VI?  Is it built into an executable?  If this is a RT VI, you cannot use event structures.  More details are available in this KB:

Can I Use the Event Structure in LabVIEW RT?

I assume you have seen this? 

How Can I View Remote LabVIEW Real-Time Front Panels in a Web Browser?

 Are you still having the cRio reset issue and CPU usage increase?

Kristen H.

[xkenneth]

Yes. When I attempt to access my remote front panel the cRIO stalls and resets.

[Kristen_K.]

Hi xkenneth,

This is probably a silly question but sometimes silly things happen. There's not a reset function in the VI is there?   Also, does the VI run okay without the remote front panel enabled?  Do the issues only appear when the remote front panel is used, including CPU usage?

Kristen H.