topic Re: Subpanels, Waveform Charts, Async VIs in LabVIEW

Subpanels, Waveform Charts, Async VIs

gsklyr — Fri, 20 Sep 2019 16:19:59 GMT

Hi All,

I am starting 4 VIs with Async call and inserting each one into a subpanel in 4 tabs (each tab has a subpanel). It is the same VI I am using 4 times. The VI has a waveform chart in it. When tabbing through the 4 tabs, the waveform chart in each subpanel resets and starts plotting new data as soon as I tab into it. Any idea why? All other parameter/timers/counters do not reset and run asynchronously as expected.

Re: Subpanels, Waveform Charts, Async VIs

JÞB — Fri, 20 Sep 2019 16:28:24 GMT

It would really aid us in helping you if you attached the subvi

Re: Subpanels, Waveform Charts, Async VIs

Ben — Fri, 20 Sep 2019 19:43:39 GMT

Scarce little to go on but I will throw out an idea based on the fact you said you are using a Waveform Chart and I see globals in the code.

A chart that uses a Waveform data type will reset (clear the plot) and start plotting from the beginning when ever a new update is not consistent with what is already plotted.

Examples;

The channel names change

The T0 of the new data is older that data already in the chart

So if your tabbing is introducing a timing issue that results in the charts getting a new set of channel names or old T0 timestamps... it would explain what you described.

You may want to skip putting them in the subpanels and just showing the FPs to see if that make a difference.

Ben

Re: Subpanels, Waveform Charts, Async VIs

gsklyr — Fri, 20 Sep 2019 20:10:39 GMT

Ben, thank you for the insight. Going to investigate that route soon.

Re: Subpanels, Waveform Charts, Async VIs

Bob_Schor — Sat, 21 Sep 2019 01:48:49 GMT

I'm not sure I understand what you are doing, and (of course) without your code I can't really find out, but I'm puzzled by your description of four tabs (which sounds like a Tab Control) each with four sub-Panels. You also seem to have (I don't know how many) detached asynchronous routines doing I'm-not-sure what.

I had a project that involved recording analog data from multiple stations. I wrote a single sub-VI that acquired the data from one station and displayed the result on a Waveform Chart on its front panel. Let's say I had 10 of these running simultaneously. My main routine would launch all 10 clones and have them update their own front panels. In the Main routine, I could select which of the 10 I wanted to view, and all I had to do was to put it in the single sub-Panel and I could see its evolving Chart. I could switch between them as fast as I could change the selector. Very simple, easy to program, easy to organize.

I'm looking forward to seeing your code to understand what you are doing. Maybe there's a simpler way ...

Bob Schor

Re: Subpanels, Waveform Charts, Async VIs

drjdpowell — Sat, 21 Sep 2019 08:04:42 GMT

Could be a UI thing, where the data is there but not drawn. Try changing one of the scales to force a redraw.

Re: Subpanels, Waveform Charts, Async VIs

JÞB — Sat, 21 Sep 2019 11:01:54 GMT

@gsklyr wrote:

Ben, thank you for the insight. Going to investigate that route soon.

With respect to Ben's insights...

I Hate Tabs. subpanels on tab containers that display charts are not going to play nicely. That's just the way tab containers work....you "refresh" the data on the Tab Pane when you activate the view of a specific tab.

User viewable data updates on hidden tab views is generally ignored by the OS (the USER has chosen to pay no attention to the data behind the screen by selecting a different view from the tab containers view control)

A control with a history display e,g, a chart....makes no sence on a tab and double nonsense in a subpanel on a hidden tab view.

That being said, does the subvi have a panel actvation Event?

Re: Subpanels, Waveform Charts, Async VIs

mcduff — Sat, 21 Sep 2019 16:55:47 GMT

Why not 1 sub panel and a set of radio buttons to switch views? Seems like it would easy to implement/change your current VI.

mcduff

Re: Subpanels, Waveform Charts, Async VIs

Bob_Schor — Sat, 21 Sep 2019 18:40:00 GMT

I agree with McDuff (how did he know I was using Radio Buttons to choose which of my Asynchronous Clones had the display I wanted to see?)(See my earlier reply -- sorry I wasn't as succinct as McDuff).

Bob Schor

Re: Subpanels, Waveform Charts, Async VIs

JÞB — Sat, 21 Sep 2019 18:59:47 GMT

@Bob_Schor wrote:

I agree with McDuff (how did he know I was using Radio Buttons to choose which of my Asynchronous Clones had the display I wanted to see?)(See my earlier reply -- sorry I wasn't as succinct as McDuff).

Bob Schor

Because mcduff has read the same posts by me as you have and assumes.

Tab containers are hateful

Re: Subpanels, Waveform Charts, Async VIs

Ben — Mon, 23 Sep 2019 12:49:38 GMT

@JÞB wrote:

...

Tab containers are hateful

I am not sure what about tabs left you with a sour taste, but they work OK for me.

Sure, in the early days there were issues with charts on hidden pages not updating as expected. I recall having to implement "jiggle the handle" type code to ensure the charts updated. But it has been years since I ran into those types of issues and I DO use tab with and without charts in many if not all of my applications.

Now when I have to develop for novice customers to support the code I deliver and "writing to my audience", I find tab controls easier for them to grasp than sub-panels.

So for what it is worth,...

Before the tab control was introduced... problably LV 5.1 or so I found myself implementing a very complex GUI that required hiding and showing groups of controls and indicators. Lacking the tab control the code was dominated by attribute nodes since the "grouping" of controls and indicators that we gain from tab controls was not available. Now since it was in LV 5.1, there was no option to use control refs and sub-VIs to handle the visibility, it all had to be done in the top-level! With all of that code just to handle the look and feel it was difficult to find what code actually did anything!

While I can not be sure, I suspect that code is one of the examples that NI trots out as bad code. While it may be unfair showing code developed for LV 5.1 and presenting it as bad code in the world of property nodes and ActiveX, it does give one an opportunity to appreciate control refs and tab controls.

I still use tab controls.

Ben

Re: Subpanels, Waveform Charts, Async VIs

gsklyr — Tue, 24 Sep 2019 15:52:21 GMT

Some great thoughts and ideas, thank you!

So I have changed my top level VI to a single subpanel with some buttons and an event structure to decide which VI will be swapped into view. While it is a good improvement to my overall program, waveform charts still start plotting from scratch when a VI is inserted into the subpanel. My guess is that if you don't have a physical view of the VI, it won't update the chart. I am considering having 4 subpanels stacked on top of each other and 3 of them hidden at a time.

Re: Subpanels, Waveform Charts, Async VIs

Ben — Tue, 24 Sep 2019 16:51:08 GMT

Old versions of LV had issues with the chart if not viewed.

I believe you have ruled out the tab control as a suspect so we should now question the VI you are inserting in the sub-panel is the culprit.

Dumb down the inserted sub-VI as much as you can (while preserving the questionable behavior) and share that with us so that we can take a look since (inquiring minds) want to know about problems before we stumble over them ourselves.

Share the inserted sub-VI.

Note:

Without you sharing an example of the issue, I do not suspect there is much we can do to help.

Ben

Re: Subpanels, Waveform Charts, Async VIs

Bob_Schor — Wed, 25 Sep 2019 02:40:26 GMT

So I have changed my top level VI to a single subpanel with some buttons and an event structure to decide which VI will be swapped into view. While it is a good improvement to my overall program, waveform charts still start plotting from scratch when a VI is inserted into the subpanel. My guess is that if you don't have a physical view of the VI, it won't update the chart. I am considering having 4 subpanels stacked on top of each other and 3 of them hidden at a time.

I can definitely state that this is not the case. I have a routine with multiple independent processes producing graphs on their Front Panels. As they are running as sub-VI, none of these Graphs are visible, but by pushing a (Radio) button, I can insert any of them into my Main VI's sub-Panel, and see the (evolving) Graph. I'm using a Graph rather than a Chart, but I'm 99.44% certain I could build a demo that does this with Charts, as well (if you'd like me to try, send an encouraging Reply and I'll give it a shot tomorrow). So if it isn't working for you, the problem (probably) likes in your sub-VI that you are inserting into the sub-Panel. Attach it to your Reply and I'll bet one of us can make some helpful suggestions ...

Bob Schor

Re: Subpanels, Waveform Charts, Async VIs

JÞB — Wed, 25 Sep 2019 05:04:26 GMT

@Ben wrote:

Old versions of LV had issues with the chart if not viewed.

I believe you have ruled out the tab control as a suspect so we should now question the VI you are inserting in the sub-panel is the culprit.

Dumb down the inserted sub-VI as much as you can (while preserving the questionable behavior) and share that with us so that we can take a look since (inquiring minds) want to know about problems before we stumble over them ourselves.

Share the inserted sub-VI.

Note:

Without you sharing an example of the issue, I do not suspect there is much we can do to help.

Ben

I thought I said that last week. We reallly can't debug code that we cannot see!

( I am still betting on a panel activation event.... but my magic 8-Ball is located on my desk in North America while I am in Europe)

Re: Subpanels, Waveform Charts, Async VIs

gsklyr — Wed, 25 Sep 2019 16:18:44 GMT

Current situation:

- I have 4 stacked subpanels with an async instance of my subVI inserted in each one.

- 3 of the subpanels are invisible at a time.

- When I switch away from a subpanel and come back to it, it does not re-plot the data anymore, BUT there is a blank space in the plot for the time it was not visible!

Questions:

1. What is a panel activation event?

2. If all 4 stacked subpanels are visible, can I programatically bring one subpanel to the front or move the other 3 out of the screen?

Finally, my top level VI and the plotting loop in the subVI:

Top Level. The other events just hide/unhide subpanelsChart Loop

Re: Subpanels, Waveform Charts, Async VIs

cbutcher — Wed, 25 Sep 2019 17:06:39 GMT

I know this isn't exactly the point of this thread, but why have multiple hidden subpanels?

You could simplify your code by having just a single subpanel and an array of references, then choosing which VI reference to insert to the subpanel (from the array formed by the async running copies) using whichever method you liked.

Re: Subpanels, Waveform Charts, Async VIs

gsklyr — Wed, 25 Sep 2019 17:17:10 GMT

I have tried that. When I remove a VI and load a different one into the subpanel, the waveform chart in that VI restarts the plot.

Re: Subpanels, Waveform Charts, Async VIs

Ben — Wed, 25 Sep 2019 17:47:54 GMT

Check;

Properties >>> Execution

of the inserted VI and verify the "Non-Reentrent" is NOT selected.

Ben

Re: Subpanels, Waveform Charts, Async VIs

mcduff — Wed, 25 Sep 2019 17:50:47 GMT

@Ben wrote:

Check;

Properties >>> Execution

of the inserted VI and verify the "Non-Reentrent" is NOT selected.

Ben

Another thing to try: Disable the subpanel control, set the VI to open the front panel when called, that way you have a bunch of windows open. Are all of the plot window updating properly? If not, then look into settings, controls, etc.

mcduff