Updating Listbox in a while loop

Hi,
I'm a newbie.
I would like to have a directory listing in a listbox updated
continuously.
I have an array of file names going into the Item Names property node,
then the value and string array are put into an "index array" which
goes to an indicator.
Now it works fine when I run it once but, if I run it in a while loop
I can't select any items in the Listbox.
Can someone tell me what I'm doing wrong?
thanx

Hi,
I'm not sure that I've got the problem corrcetly. It is always better to send your VI with message. But I tried to make an example and it works fine in my case.
Is it what you want?
Oleg Chtuko.
Attachments:
List.vi ‏27 KB

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Updating widgets on panel while looping

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Hi Florian, We had the same problem and we use the following code to update our static text widgets immediately, instead of waiting for the next update event to trigger the redraw.This can probably be applied to any type of widget, as long as you have the widget IControlView. The code was only necessary for MacOS - on Windows, the static text was updated immediately. IControlView* aWidgetView = [your control view]; if(aWidgetView != NULL) { ViewPortAccess<IWindowPort> aWindowPort(lWidgetView, IID_IWINDOWPORT); if(aWindowPort) { InterfacePtr<IViewPort> aViewPort(lWindowPort, IID_IVIEWPORT); if(aViewPort) { AGMGraphicsContext gc(aViewPort, aWidgetView); aWidgetView->Draw(aViewPort); #if MAC_OS if (gc.GetSysPort() != nil ) { if ( ::QDIsPortBuffered(gc.GetSysPort()) && ::QDIsPortBufferDirty(gc.GetSysPort()) ) { ::QDFlushPortBuffer(gc.GetSysPort(), nil); } } #endif } } } - Chris

Start stop while loop with tab control

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Solved!
Go to Solution.
Attachments:
Loop test.vi ‏16 KB

The problem is that you can't even stop the program by hitting the stop button until you leave the tab, which is not a friendly user interface.
Event structures should just handle basic user events. Any given event case should not take a long time to run. While you are in the diagnostics tab, your code is stuck in that while loop. Although fixing the lock front panel allows you to do other things, the LabVIEW is just queuing up all of those other UI events (like Stop button value change) and can't handle them until the inner while loop stops and allows the outer while loop to iterate again.
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How can I update cluster items from inside a while loop that does not contain the cluster?

I have a VI that contains front panel clusters and two while loops. The main cluster contains items such as a doubles "distance" and "stepsize" and boolean "step" (a whole buch of this type stuff). The first loop contains an event structure to detect front panel changes and the second contains code and sub VIs to perform operations based on detected events.
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Hi Ben,
Thank you for the response. I followed the link and tried reading everything you posted on AEs but I'm afraid that I didn't understand it all. It seems that each AE example had a single input and a single output (e.g. a double). Is this the case?
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Front Panel Reference.vi ‏33 KB

How come my local variable is not updating it's value with respect to what's happening in the while loop?

Hello,
I am trying to extract data out of a while loop as my declarations update with respect to the iteration number. I have attempted to use both local variables and shift registers, but with no luck.
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Solved!
Go to Solution.
Attachments:
Local Variable.png ‏366 KB

OK, looking at the code...
Can you explain what it is supposed to do? What's the purpose of the value property node read which only seems to update an indicator.
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LabVIEW Champion . Do more with less code and in less time .

Getting data from a while loop while running.

Hello,
I did a program that call a sub-VI which is doing experiment and have its own timer.
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Thank you,
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I tried using shared variable and reference without succes.
I will keep searching.
I enclose my VI that I simplify the most but with still keeping the shape of my real program. If you can take a look I will really appreciate.
The goal is on the top-level VI to be able to see the updating data time in real time.
Thanks,
Meach
Message Edited by Meach on 07-23-2008 04:13 PM
Message Edited by Meach on 07-23-2008 04:14 PM
Attachments:
Elapsed Time.zip ‏25 KB

How to stop while loop

I can't figure out how to stop a while loop in my labview program.
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SPoleLakeChirp.vi ‏199 KB

Dennis and altenbach- Thank you both for your patience.
I was trying to do just what Dennis suggested-"As I said, setting a local variable is one way." even before posting to this forum, but I couldn't get my local variables to reflect changes made elsewhere in the program and I wasn't able to wire from them because they were writes. The critical part I was missing was how to change a local variable from a write to a read. It was staring me in the face the whole time- just right click. When I finally found it, my problems were solved.
altenbach- thank's for putting the figures together. I do understand the logic and wiring there, but I was really trying to avoid stop buttons. The program should be smart enough to figure out when to stop. And using local variables turns out to be one way of solving this. I still have some clean up to do, but I've included my current working version just so you can see how I implimented your suggestions. There's still a lot of clean up to be done, but I'm delighted to be able to watch the serial/gps messages until I'm done reading in data. At first I had this stop variable set in the final sequence frame. That didn't work because I wasn't getting to the final frame because the loop wasn't finishing. Once I placed the stop variable in the same frame as the while loop it began stopping when it should.
If you have other comments/critiques about the wiring diagram I'm earger to hear them. I'm considering the structure finished, however. It still needs cleaning up and commenting, but I'm satisfied with the functionality.
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SPoleLakeChirp.vi ‏210 KB

How to stop While Loop in Event Structure with same button?

Hello,
I have a problem. I want to use one control to activate an event in a event structure, and the same control to terminate a while loop in that event.
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Message Edited by Heinen on 02-19-2009 06:16 AM
Message Edited by Heinen on 02-19-2009 06:20 AM
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Solved!
Go to Solution.

Hello,
I have a bit different problem.
I have a tab control, with several buttons on different pages.
In the current situation, we can talk about two pages, where one page ("Settings") in the Image, has a START and EXIT button, while second page ("Wait") has an EXIT button.
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Vaibhav
Attachments:
terminate event_diagram.jpg ‏200 KB
terminate event_front_1.jpg ‏63 KB
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Plot XY graph from while loop

I am trying to make a curve tracer with a DC power supply, DAQ, and Labview 7.1. Everything is ok, until I want to plot an x-y plot from a while loop. I can do this function fine using a for loop and cluster cells, but I need the while loop for the interruption function. When I change to the while loop, it had data formating issues, but I believe I have it to something that should work. It seems like my xy plots want to graph (the auto scale moves the axis respectively) but I do not get a line. I'm not sure if Labview is seing this as just one point and not an array, or if there is a labview bug. Attached is my code with a few different trials to make an xy plot. If anyone can be of help I would be very thankful.
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Curve_trace_w_relays_while.vi ‏122 KB

If it works in a FOR loop, but nor in a while loop, most likely your output tunnels are not autoindexing (FOR: on by default, WHILE: off by default). Right-click on the output tunnels and select "enable indexing".
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LabVIEW Champion . Do more with less code and in less time .
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Curve_trace_w_relays_whileMOD.vi ‏74 KB

Updating data outside a foor loop

I hope someone can help me with the following problem. I collect data into an array with a for loop. The data is visualized in an intensity graph. All this works fine. I would like to update the graph line by line as the for loop runs. I managed this too but only if the graphing is done in the same VI as the for loop. This I would like to avoid as the program is already rather complex and it is difficult to keep track of all the things. I therefore made the for loop data acquisition into a subVI but now the updating doesn't seem to work. My question is, is it possible to update data outside a for loop when the loop and the data are in different VIs.
Klas

Hi
It is a good way, doing it like that.
There are also other ways. And the easiest one, that people tend to use imediately are the global variables.
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Making a connector in while loop

I want to make a subvi with a while loop.
For example, there is a indicator inside while or for loop as my attachment.
Actually, the indicator will be used as a progress bar which need to be updated in realtime in main vi.
In my first thinking, the subvi is used in a simple event-driven structure(main vi) to start by a button (for user interface).
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Lee
메시지가 08-12-2007 07:30 PM에 labmaster에 의해 편집되었음
Attachments:
aaa.jpg ‏13 KB

trivial example attached, two vis in labview 8.2.1
Paul <--Always Learning!!!
sense and simplicity.
Browse my sample VIs?
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subviThatUpdatesMainProgess.vi ‏10 KB

Is there a way to cycle a while loop on its own and only controlled by the number of cycles?

Hello everyone,
Newcomer here, recenlty just took core 1 and 2 the past couple of months
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Attachments:
TEST RIG 11 10-28-13.vi ‏298 KB

You took core 1 and 2!!! Please tell me NI didn't teach it. I'm not trying to harp on you too bad because I think the instructor is more to blame. You have many wires going the wrong direction, multple loops doing nothing, and one loop that will never stop so even if all the others did there would be no way to stop your program, a Stop button that is read only once at the start of the application and then is never read again (so stop will never work). You have the inner loop running forever, but even if it did stop it would run the outer loop forever, your enums should be typedefed, uninitialized shift registers when not needed, dynamic data types, far too many express VIs...ouch.
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Writing a file for prescribed amount of time in a while loop after the triggering condition is met

Hello Guys,
I am trying to program an application in which if the trigger condition is met it should start to write the file.
I was able to do that, but if I want it to be written for certain amount of time, and once the trigger condition is met, it should continue to write the files for prescribed amount of time. I was not able to do this. The file name should also be updated accordingly.
I tried to with some options by keeping the creation of the file outside of the loop, if I do that then if the trigger condition is not met it will stop writing and I dont want that, as once the trigger condition is met it should be true thereafter.
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Attachments:
PXI_4462_Sync_and_Stream_trigger.zip ‏192 KB

what i am saying is to keep track of how much data you have written and whenever you need to make a new file you make 1.
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Attachments:
new file exemple.vi.zip ‏21 KB

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We have a while loop that is monitoring 6 sensors in a heated water bath.
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Attachments:
switch pass or fail vi question Oct 17 2011.zip ‏575 KB

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Hello friends,
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Please do NOT attach .bmp images with the extension changed to .jpg to circumvent the forum filters!
Herok wrote:
I am sending you the VI. I am not sure if this would help you because only in 2 computers this behaviour is seen. In others, it works as it is supposed to work.
Whatever you are seeing must be due to some corruption or folding error. It all works fine here.
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LabVIEW Champion . Do more with less code and in less time .

Updating Listbox in a while loop

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