WaveformChart- intermediate Xscale marker labels are lost at small X mulitplers

[TimTower]

I recently upgraded from LV711 to LV821. Seems OK, except that I am getting some strange behavior with my waveform charts. If the X-scale multiplier is smaller than about 0.1, the intermediate X-scale marker labels (in this case, time (H:M:S.xxx) and MM/DD are sometimes lost. This gets worse as the multiplier is reduced. For example, if I am displaying a 1 kHz waveform graph, the multiplier is 1/1000 = .001. In this case, only the beginning and end date/time stamps are shown on the X-axis. It does not help if one zooms in or out – none of the intermediate stamps are shown. I have tried changing the X-axis display style, display length, markers, etc. Nothing seems to help.  Note that if one uses multipliers of 0.1 and larger, the problem goes away.

This is not useful. I need to have the intermediate markers, otherwise the data is hard to inspect. I am running my charts up to 9 kHz, in which case the multiplier is 1/9000=.0001111.

See the attached example, saved under LV8.2.1. The lower of the 3 examples is a chart from my app; the other two are graphs, from an NI example. The graphs show the same behavior.

I have tried using a new chart from the LV821 palette. Same behavior.

For ref, this problem does not occur under LV711. Anyone know how to fix this?  Thanks!

[Yi Y]

Hi TimTower,
This appears to be a reproducible bug.  The waveform chart behaves somewhat irratically when the scaling multiplier is smaller than .01, and I'll have to file a bug report on it.
Meanwhile, you might consider using waveform graph instead, as that seems to be working fine.

Yi Y.
Applications Engineer
National Instruments
http://www.ni.com/support

[TimTower]

Hi Yi
Thanks for the quick response. I tried replacing the Waveform chart with a Waveform graph. My VI was broken, with 41 errors. Many properties have broken lines. My VI is quite sophisticated, and makes extensive use of graph properties, for repositioning other items on the FP, auto scaling, auto resizing the Graph pane, etc. Also, it has a fairly large history buffer (131K records), which are exported programmatically to an analysis program. I doubt it will be easy to port this VI (and another related graph VI) to using a waveform graph - the chart and graph controls are too different.
I have since installed LV85 and it shows the same behavior. So, right now it seems I am pretty much stuck. I am trying to port over all my VIs (about 1500) for my customers projects, from LV711. I first tried this in Jan, noticed this problem, and bagged it, not having the time to investigate it fully (and post something on the NI website). This is my second attempt. I have spent quite a few days on this. Does this mean I will have to go back to LV711? Oh dear, that does not excite me, and the revs I have since made to my VIs in LV82/ 85 will need to be ported back too - not easy, since one must first port back to 8.0.
Any idea how long it might take to fix this? All I need is the same waveform chart behavior as existed in LV711.
Thanks
Tim

[Yi Y]

Hi TimTower,
A co-worker and I poked around a lot more and found a work around.
Right click on the legend of the waveform chart, change the X-scale marker spacing to Arbitrary instead of Uniform, then right click on the part of the legend where you want to add intermediat markers and do X scale->Add Marker.
The problem is that for some reason the major markers seems to be not displaying correctly when multiplier is smaller than a certain value.  Therefore, you have to define where you want the markers to be yourself.
Hopefully this is an acceptable work around for you.  I will file the bug report to R&D so they will look into a fix for the problem.  I will come back shortly to post the bug report ID.

Yi Y.
Applications Engineer
National Instruments
http://www.ni.com/support

[TimTower]

Hi Yi
I tried this. Clever idea! However, I don’t think this will work for me. I can use your new method to create arbitrary markers on the chart at a given scaling, but if I then zoom in (for example, if I look at my entire graph - say, 20 sec worth, and add some markers, and then I zoom in to look at a 3 msec "window" of the data), the markers no longer appear. It seems they are for a given zoom level. Another problem is that when I zoom in, I need the markers to be at a uniform spacing - for example, at 5.0, 6.0 and 7.0 msec. It is not easy to create such uniform spacings when one adds these manually.

Is there a way to create these markers programmatically? I could look at the chart start and end times, and calculate a marker spacing and quantity of markers, and apply these at each zoom level. Probably not too difficult.

Any idea how long it normally takes to get a bug fix? How will I know this has been fixed, so I can schedule a S/W update with my customers?

Thanks for your help. You guys do a great job!
Tim

[Yi Y]

Hi TimTower,
I messed around with it quite a bit, and I wrote a VI that would've been a work around for your zoom issue.  However, it's displaying almost the exact same symptom as what the original bug was--if the multiplier is smaller than .01, the markers in the middle disappear.  I'm attaching the VI just in case if somebody else on the forum can catch something that I missed.  However, this is looking like a bug that's probably related to what you are seeing before.
Currently the best option would probably be not use absolute time but use Floating point or Relative time, in which case the problem doesn't occur.
There's no definite time frame as to when R&D will be able to fix this problem.  So I unfortunately cannot answer that question.  If I hear any information regarding that from R&D, I will let you know.

Thanks!

Yi Y.
Applications Engineer
National Instruments
http://www.ni.com/support

[Yi Y]

Hi TimTower,
I filed the CAR, and the CAR ID is 4D3JOV68.
I looked more into the VI, and was finally able to make a somewhat usable workaround VI.
Let me know if you have any questions.

Yi Y.
Applications Engineer
National Instruments
http://www.ni.com/support

[TimTower]

Hi Yi
Sorry for the delay - I have been off on another project. Interesting piece of code whcih you wrote. I note that it does create the intermediate markers, which is an improvement. However, it does not seem to create the time stamp labels, as LV711 used to do. I need these, as my customers and I zoom in sometimes with say 10 ms covering the x-axis of a chart which is 16" wide on the screen. It is not easy to have them count divisions from one end to see what the time value of an intermediate X-scale marker is. LV711 seems to be smart enough to choose a reasonable number of X-axis time labels - in this case, it would be 6 or even 11 (vs only 2 for LV8.x)

Thanks for putting in a bug fix request. I suppose I will have to wait until the next rev comes out (8.5.1?) and hope this has been fixed. Until then, I cannot upgrade myself or my customers. I have LV711, 8.0 and 85 on my PC at present, but once I upgrade my VIs to 85 there will be almost no chance of reverting - I tried this (85->80->711) and it doesnt do everything quite right. Takes quite a bit of fudging to get back to 711. The versions are simply too different.

I dont suppose there is a log kept at NI's website which one could check periodically to see the status of a bug fix request?

Thanks
TIm

[RDR]

There is a list of bug fixes released with each version of LabVIEW where you can look up CAR IDs to see if they were corrected.  Similar to the list found here: http://zone.ni.com/devzone/cda/tut/p/id/6448


-Bob

[Yi Y]

Hi Tim,
It appears that I posted an incorrect CAR number in my previous post. The correct ID is 4D3KLC68. Sorry about that. The bug has already been assigned to an R&D owner, but they are still working on it. We will let you know as soon as we find out any new information.

Yi Y.
Applications Engineer
National Instruments
http://www.ni.com/support