Real-Time Waveform Chart causes 100% CPU After Jan 2006

[Sirin]

I have had a VI running for 6 months without issue, then suddenly multiple customer sites have called me with an issue where my program will cease to function and take 100% of the CPU. After a bit of troubleshooting, I discovered that the root cause was a waveform chart in my program. If the customer set the system time/date back even a month, the program worked as normal, but for dates after the end of January 2006 the program takes 100% CPU as soon as I set up the axis of the graph and begin writing points to it.

I am attaching an example VI that just contains an example portion of the code, and does actually cause the symptoms I've described. Sometimes you have to run the VI twice in order to see an issue, I'm not sure why.

I was wondering if you guys out there had any thoughts on why this has started occuring. I have 'fixed' this issue in my software by no longer having an X-axis that displays actual system time. (I instead changed the waveform chart X-axis to be decimal relative time.

I use Windows 2000 and LabVIEW 6.1 Base Development Edition with Application Builder.

[smercurio_fc]

Interesting. I ran your VI under 7.1 and 8 and had the same problem. The CPU gets pegged at the property node and only if the chart contains data, so that's why it happens when you run the VI a second time. If you clear the chart before running the VI you don't get the problem. An alternative solution is to set the VI's properties to clear the indicators when called (under the "Execution" section of the VI's properties). However, I don't know if this option is available under 6.1.

[Sirin]

Well, it is good to know that I'm not going insane. I guess that is a bug they might look at for LV8.1? 😉

[johnsold]

On my Mac (Dual G5, 2.3 GHz, OSX 10.4.4, LV7.1.1) it runs at about 1.7% CPU in background (still on screen but another app in foreground), about 3.6% CPU as foreground app, and about 55% CPU if the delay is reduced to 10 ms.

Lynn

[smercurio_fc]

Sirin, if you haven't already you should post a bug report to NI so they can take a look at it. Be sure to note that the problem occurs at the property node if the chart contains data from a previous run.

[Ben]

"...you should post a bug report to NI so they can take a look at it"

I agree and have already linked this thread to this months Bug List taht can be found here.

https://forums.ni.com/t5/BreakPoint/Monthly-Bugs-February-2006/m-p/318171?jump=true

NI Support has commited to monitor all of our bug postings.

Ben

[AG123]

Hello Everybody,

Thank you for alerting us of this issue.  I was able to reproduce this issue, and filed a corrective action request to our R&D department. 

I am sorry you are seeing this problem.

Best Regards, and thanks again,

AG,

National Instruments

[THailey3]

This was reported to R&D (# 3U5A86ET) and was fixed in LabVIEW 8.2. Here is a link to the current evaluation software download for LabVIEW.

Thanks!