Unload front panel

Hi all,
May I know how can I unload (not only hide it but unload from memory) a subvi's front panel? Let's say I have a main vi, and the subvi is shown when the button is pressed from the main vi.. Then how can I unload the subvi when the button is pressed from the subvi? And most importantly how I can pass the value from the subvi into main vi? An example for this will be highly appreciated.. THANKS!!

Here is a set of vis for your reference. Try it out and let us know if you still don't get it. Please note that the attached vis are very simple and done quickly.
Attachments:
Main1.vi ‏18 KB
SubVI1.vi ‏14 KB

Similar Messages

Multiple subvi's in main front panel

Hello and welcome (it is my first post here),
sorry if such subject was already risen, however I don't know how to specify it exactly in terms of LV nomenclature (I'm a beginner in LV) what makes it quite difficult to search the forum.
I need to create an interface with user specified number of input channels (specified during application work, so dynamic loading is necessary). Each channel is to be controlled by subVI. I'd like to load panels of all running input subVI's into some container in a main front panel (similarly to subpanel, but loading multiple VI, not single one). Is there a container capable of this? Is it at all possible in LV?
Regards,
kaolpr
Solved!
Go to Solution.

You can use multiple subpanels. Unfortunately the number of subpanels must be set during development. You could create a method of cycling through your various channels. This would involve loading and unloading the multiple subpanels that you do include in the UI.
Another alternative would be to use a table or something similar. Have your subVIs post updates to the UI code via queues, notifiers or user events. Tables are much easier to manage when your number of elements varies. If you need to have the UI pass information to the subVIs it can also use queues, notifiers or user events.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

Selecting front panel properties after runing causes crash

After I run my program (which uses several call library function nodes to access numerous dll files) and then try to alter the properties of a front panel control labview crashes. Sometimes it simply locks up, other times it displays a recoverable error message, and finally sometimes it displays a hard error message from which I cannot recover and only send an "error report." While the errors are annoying I really want to know why changing the properties causes them which may lead me to other problems in my code. Thanks for any thoughts you can provide.
-Dave

NIDave wrote:
> Thanks for the reply Jeremy, I try to change them manually after the
> program stops. I use a property node to alter other controls but not
> the one I discovered the problem on. I am suspecting a memory leak
> within the dll or some problem with the way I am passing strings and
> arrays in and out of my call library function nodes. (I initialize
> the strings and arrays before the function is called, so I am leaning
> toward an issue in the C code.
Well here you go. Calling a DLL and then getting (delayed) crashes in
LabVIEW absolutely always means that the DLL is trashing some memory it
shouldn't. This either happens by passing wrong data (DLL expects by
reference and you pass by value) or arrays and string not initialized or
not intialized to be large enough. Last but not least the DLL of course
can just simply be buggy and do stupid things.
So you will have to verify somehow that the DLL works correct outside of
LabVIEW. If you have verified that, then you need to check all
parameters of all function calls into the DLL to be correct and also
large enough for the DLL.
Especially make sure that for strings you allocate 1 more byte than the
longest string the DLL may want to write into, and for arrays that you
allocate the right number of elements of the right type. Sometimes the
documents state that the array must be at least 100 elements long but if
this is an integer then that amounts actually to 400 bytes.
> Also another oddity, when I first open labview and run the code it
> works great, however if I try to close the VI but not labview then
> run it again it fails. I think that labview is not dropping the dll.
> Is there a way to force it to release the dll?
Not really. A DLL should not depend on being unloaded to be callable
again. But the error you describe could be because of several reasons.
Basically make sure you call any existing Close or similar function at
the end as well as initialization function in the beginning. Also the
error could be related to the DLL trashing memory somewhere. So try to
get the DLL to work properly without any bad effects after having it run
once including no crash when unloading the VI, closing any front panel,
doing some LabVIEW edit functions or last but not least closing LabVIEW.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Open and close a vi front panel dynamically

I created a main vi panel that display all the signal names. I like the main vi to open a new plot screen when I double click on the signal name. I was able to do that using invoke node. But I when I close the plot screen by clicking on the Window "Close" button, the main vi was not able to open a new one again. So I disabled the Window "Close" button and only use the "Stop" button coded in while loop in the blockdigram of the plot screen. It worked, but the plot screen is still open and changed to editing mode. Is there an easy way to close the plot screen by only one click. Another question is that how does the main vi can open multiple plot screens. Thanks for your advice.

I think I know what happens:
If you close the front panel of a sub-vi, the code is still running, so the VI doesn't terminate and somehow you can't address it (it don't know how you communicate with your sub-vi).
So in your sub-vi you should monitor the panel-close event, and finish the code of the VI and finish the VI
Ton
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Open and Close Front Panel of SubVI

Hi all,
Running LabVIEW 2011 on Windows 7 x64. I am trying to get a subVI front panel to open from my main FP with the press of a button and then close with a button press in the subVI. Here is the piece from my main FP that calls the VI and opens the FP
Plots is defined in another loop and all of the loops are in a flat sequence. I did it this way because I want it to start with the first press and not stop my main loop from running. I have moved the item in the left loop around a lot so I'm not sure if I can run that in the same loop as the event or not. Either way opening the VI seems to work fine.
The problem shows up when trying to close the subVI for the SECOND time. The code is here:
As I said, the first time I open and close the VI everything works as I expect it should. I am then able to open it again but now the "blank button" doesn't function and I can't close the window or even open the block diagram to probe anything. I have been trying to figure this out for awhile, any insite would be greatly appreciated!
Thanks
Solved!
Go to Solution.

Its good that you found the bug.
This code may serve as a way for you to compare notes.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

I have a VI and an attched .txt data file. Now I want to read the data from the .txt file and display it as an array in the front panel. But the result is not right. Any help?

I have a VI and an attched .txt data file. Now I want to read the data from the .txt file and display it as an array in the front panel. But the result is not right. Any help?
Attachments:
try2.txt ‏2 KB
read_array.vi ‏21 KB

The problem is in the delimiters in your text file. By default, Read From Spreadsheet File.vi expects a tab delimited file. You can specify a delimiter (like a space), but Read From Spreadsheet File.vi has a problem with repeated delimiters: if you specify a single space as a delimiter and Read From Spreadsheet File.vi finds two spaces back-to-back, it stops reading that line. Your file (as I got it from your earlier post) is delimited by 4 spaces.
Here are some of your choices to fix your problem.
1. Change the source file to a tab delimited file. Your VI will then run as is.
2. Change the source file to be delimited by a single space (rather than 4), then wire a string constant containing one space to the delimiter input of Read From Spreadsheet File.vi.
3. Wire a string constant containing 4 spaces to the delimiter input of Read From Spreadsheet File.vi. Then your text file will run as is.
Depending on where your text file comes from (see more comments below), I'd vote for choice 1: a tab delimited text file. It's the most common text output of spreadsheet programs.
Comments for choices 1 and 2: Where does the text file come from? Is it automatically generated or manually generated? Will it be generated multiple times or just once? If it's manually generated or generated just once, you can use any text editor to change 4 spaces to a tab or to a single space. Note: if you want to change it to a tab delimited file, you can't enter a tab directly into a box in the search & replace dialog of many programs like notepad, but you can do a cut and paste. Before you start your search and replace (just in the text window of the editor), press tab. A tab character will be entered. Press Shift-LeftArrow (not Backspace) to highlight the tab character. Press Ctrl-X to cut the tab character. Start your search and replace (Ctrl-H in notepad in Windows 2000). Click into the Find What box. Enter four spaces. Click into the Replace With box. Press Ctrl-V to paste the tab character. And another thing: older versions of notepad don't have search and replace. Use any editor or word processor that does.

Square root symbol in front panel

how to inser a square root symbol in the front panel in the given vi snippet? i want to write V3 instead of sqrt(3). using Labview 8.6.
Solved!
Go to Solution.
Attachments:
GUI.png ‏15 KB

Hi,
Thank you all.. I could insert the sqrt symbol in the GUI.
I also want to initialise one of the strings with the same symbol. So I copied the sqrt symbol and inserted that in place of "sqrt(3)" . but it switched back to a special character. I selected that special character and selected symbol font from the font menu, then it switched back to sqrt symbol. but as soon as i clicked the mouse outside, it reverted to the old special character(may be the one corresponding to 0xD3 in Application Font).
How to fix this?
Attachments:
sqrtinit.png ‏5 KB
sqrt_reverted.png ‏5 KB

Front Panel Mass Binding Project Variables Issue

Hello -
When attempting to bind controls to shared variables through the front panel mass binding option, there is an issue where you can not seem to bind a "project item" to the control. The method of binding I am using is to export a text list of control names, urls, mode, and function to a text editor utilizing the front panel binding mass configuration options. The text editor shows, in the fourth column, a "0" for no function, a "1" for network item, and a "2" for project item. when attempting to import the list back into the front panel binding mass configuration, all "2" indications become "1", as all items are treated as network. Thus one can not effectively bind to a project shared variable item.
The binding works fine manually by means of utilizing the properties selection of the control, but it is difficult to do this for 821 controls, as in my application.
My application is based on a OPC served group of 821 variables which are linked to controls and indicators through the shared variable representation for each item created in the multiple variable editor.
Does anyone have a work around for this issue, as it is a showstopper right now, ie, you can not effectively bind a large quantity of controls or indicators to project located shared variables as required.
The rationale behind utilizing project located variables instead of network located variables is to reduce the amount of calls to the OPC server which was causnig a large latency in the refresh of the 821 items. With the items defined as shared variables within the project, a single call is issued, which has tremendously sped up the refresh cycle for the list of variables.
Thank you in advance for your insight in this matter,
John DeCroos

Hello Brian A.,
In response to you comment --
"in 2006, and John did not follow up with any more information for Efosa"
-- a great deal of information was provided to NI (Efosa and many, many others, up to the product manager for the DCS module). I have never heard back on a fix for this bug for the identified version of LabVIEW. The reply by Efosa here was well after we had shipped our product -- (please see date + Efosa's apology) -- we had found our own solution as is identified in the original post.
My solution was, as is also indicated in my original post, to manually bind each variable. This was unbelievably time consuming, but was all I had.
The version of software I am now working on uses far less variables, manually bound to avoid the multiple binding issue we had in the past.
I have checked the mass binding function in LV 8.5.1, it works fine now. I guess it would have been nice to have had a reply that the bug had been resolved ---- would have helped me out a bit.
Thank you,
John DeCroos

Reading main VI front panel in SubVI

Hi,
I'm trying to create a subVI that writes a header text file containing info on essential parameters in my measurements. My mainVI front panel has a few dozen controls, some of them contained in a handful of clusters.
What I'd want is just to be able to access and read the values at the subVI to construct the string I want to write to the file.
I wouldn't like to proceed the dumb way, i.e., building an array of clusters or individual controls or references to them and passing that to my subVI (and, obviously not passing each individual control/cluster as a subVI input).
I figured I'd like to have some kind of refnum of the mainVI frontpanel passed to my subVI and dig use a big pile of property nodes to dig out the info that i need, inside the SubVI. Is this a feasible solution and if so, what's the way to conduct it? If not, what would be a better way?
As before, I'm using LV7 so in case you answer with block diagram examples, I'd appreciate screenshots of them.
Thanks,
Lauri

Vostokki wrote:
I'm trying to create a subVI that writes a header text file containing info on essential parameters in my measurements. My mainVI front panel has a few dozen controls, some of them contained in a handful of clusters.
What I'd want is just to be able to access and read the values at the subVI to construct the string I want to write to the file.
I wouldn't like to proceed the dumb way, i.e., building an array of clusters or individual controls or references to them and passing that to my subVI (and, obviously not passing each individual control/cluster as a subVI input).
Lauri
Actually that is the preferred way to do. Why you may ask? It is because you decouple the functionality (creating your log file header) from your specific user interface. By doing so you can reuse this VI in other places or applications. By using the references directly this ties the subVI to the calling VI. Unless the subVI is specifically doing something to the UI itself a subVI should avoid accessing data it needs via direct references. It should require the data to be wired in with the appropriate clusters, arrays or whatever your data needs are.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

How to open remote front panel of vi's within an executable from an executable.

How do I remotely open front panels of subvi's contained within an executable, where both computers just have LabVIEW Real Time loaded (programs are run as executables)? I want to use the Method: Remote Panel Open Connection to Server to make this work. I have been getting error 1032 "VI Server Access Denied". I do not want to use the web page method (connection is too slow when controlling front panel objects and I can not programmatically exit out (release control of vi) of the web page).
Ex.
PC1: Has executable1 using Remote Panel Open Connection to Server Method etc. code inside. This program will make a call to executable2 (on PC2) to open up different vi front panels (within executable2), so the controls can be changed from PC1. I want to be able to make changes to the vi's running on PC2 from PC1.
PC2: Has executable2 containing several subvi's.

Not sure if this is what you are looking for but here is how to launch executables that can interact
Putnam
Certified LabVIEW Developer
Senior Test Engineer
Currently using LV 6.1-LabVIEW 2012, RT8.5
LabVIEW Champion

Conditionally include Front Panel of a Subvi in an EXE

I want to make two versions of an EXE, one "normal" version and a debug version. I know how to set conditional disable symbols via pre/post build actions (btw. NI: these variables should REALLY be defineable per build specification; even bare command line C compilers are easier to use in that regard than Labview).
The "normal" version won't show anything but the main vi. The front panels shouldn't even be included in the exe. For the debug version I want to show the front panels on request (I've queues for sending that to the subvis). Simply calling "FP.open" does not work with an compiled exe, because I get a "resource not found" error (the front panel of the subvi is not compiled into the exe). I tried setting show "frontpanel when called" which forces the FP to be compiled into the exe, but then the FP will shortly flash on the screen, even when the first command of the subvi is hiding the frontpanel.
How can I make a subvi depending on a conditional disable symbol include its front panel into the exe without forcing it to show its frontpanel at the same time?

There are a number of things which cause LV to keep a FP when building. These include things like open when called (which you understandably don't like), but also various things which statically require the front panel. Things like changing the scrollbar settings or creating a property node for a control on the FP. Personally, my preference is for the latter because you can document it better.
If you don't actually mind whether the FP is included, you can just do that and be done with it. If you really do mind, you can check whether placing the property node for the control in a conditional disable structure has an impact on this or not. I have no idea whether it does or not, since I don't know exactly how LV will treat the code in the disabled case.
The other alternative is making two builds and configuring it for each VI:
The disadvantage here is that you have to manage two builds and do this manually for each VI.
If you want, there's a related idea on the idea exchange, but it won't actually help in your case, because it's not conditional:
http://forums.ni.com/t5/LabVIEW-Idea-Exchange/Add-a-property-to-guarantee-that-the-front-panel-of-a-...
Try to take over the world!

How to open front panel of a VI running in RT.

Hi,
I have an application to read the encoder position using the cRIO program. I have made an executable and this application runs as startup application whenever the controller reboots. Right now, i am accessing the VI of the startup exe through Remote Panel connection. This works fine but everytime i close the remote panel , i have to reboot the controller for the next view.
So is there any alterntaive to open the front panel of the VI.
I tried using VIServer but ran into errors. (i tried using front panel -open property node.did not work)
Also i do not have any VIs stored on the controller. Only the exe is stored on the ni-rt/startup folder on the RT controller.
Please let me know how to open this VI.
Thanks.

Hi Ben,
When i close the remote front panel the first time, i am terminating the RT VI which is running on startup.
So i had to reboot everytime to access the remote VI. I guess that the VI (exe) should be continuosly running when the RT is started up. The remote panel only should be opened and closed. After I close the remote panel , i want a windows VI to be opened up.
I have a Windows VI which programmatically opens connection to the RT server for opening the remote panel. The VI runs. When the user clicks Exit on this RT VI, the VI running is stopped and then another windows VI opens up. This works fine for first time. Since the RT VI is terminated, second time , if I run, it says, VI not in server memory.
Is there a method to close the remote panel programmatically in the RT VI itself. I have a Exit button in this RT VI, so if the user clicks, Exit, the program has to be running, but the remote panel has to close. There is a method called close connection to client , but this does not work in RT , as this requires VI path.. Right now , when the remote panel RT VI is launced, to close the remote panel, i click on the 'close' button on the VI title bar. Again when the remote panel is launched, there is no error. but is there a method to close the remote panel in the server(RT VI itself). i have attached the VI.
Thank you.
Attachments:
Dummytest.vi ‏39 KB

It is possible to open the front panel of a subVI more then one time at the same moment?

I want to open a subvi´s front panel several times with each one operating independently. The subvi has a ring with several variables to choose to show in a graphic. The subvi is called from a button on the Main Front Panel. It is possible to, for instance, open the subvi and set it to show a temperature graphic and click again on the button to call another instance of the same subvi and select pressure for the graphic, keeping both new windows side by side? Will I still be able to access the Main Front Panel?

Yes you can. You have to use a .vit (VI template file). There's an example here. There's also been lot's of discussion on the subject. I think if you do a search for vit, you'll be able to find additional information and examples.

How can i open front panel of a vi and run it

Hi
I have a vi that i call multiple times from another vi, however i want it to open the front panel on some calls and not on others. What is the best way to do this?
I have come up with a way and was wondering if this method was okay or is there another method that might work better escepcially since i am eventually going to create an application out of it and hope that no problems pop up then
Unititled 1 calls Untitled 2 where with one call it opens and runs Untitled 2 while with the other call it simply runs untitled 2.vi
What I did was i changed untitled 2.vi window appearance to dialog but i deselected the show front panel when called, so by simply calling the subvi form untitled 1 it works. Unititled 2 runs but does not open
Now with another call i want to open and run untitled 2.vi so by looking the attached vi you can see what i have done
Again if there is a better method that would make my vi's more efficient i would greatly appreciate it.
Reza Sed
Attachments:
Untitled 1.vi ‏24 KB
Untitled 2.vi ‏10 KB

What you did, in theory, is the correct way to do it. However, you should move the front panel open and close into Untitled2.vi and have a boolean input as to whether to show the front panel or not. This way, your calling code is cleaner, and you don't have to reproduce the code everytime you want to call the subVI and show the panel.
If you were to use Untitled2 in another project, then you woud have to go back and look how to implement the showing of the front panel in your other code. If later, you were to decide you want that VI to be maximized, then you make one change in the VI, and not in every place you ever call it showing the front panel.

Open sub VI front panel in a tab-- Possible?

Well, the question is basically in the subject: Is it possible to call sub VI's and display their front panel in a tab. I do NOT wish to have the front panel in a new window when called.
Solved!
Go to Solution.

_Faust wrote:
Well, the question is basically in the subject:<...>
The answer is also basically in the picture:
You can find SubPanel element in the same palette as the Tab Control container. Place a SubPanel on the Tab Control and wire a reference of the VI whose front panel you want to display.
Message Edited by Giedrius.S on 02-13-2010 11:08 PM
While evaluating my code please have in mind that I am a LV novice. Therefore sometimes my code might violate some coding rules that I have to learn about myself. But how else could I do that...
Chart zoom with "Mouse Over" effect

Unload front panel

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