topic Re: open vi reference by string in executable in LabVIEW

open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 12:06:48 GMT

Hi all,

Scenario: A top-most vi (main.vi) calls two subvis (subvi1.vi and subvi2.vi) separately such that they run in parallel. subvi1.vi has a front panel that appears when called, subvi2.vi does not.

subvi2.vi uses Open vi Reference to get a reference to subvi1.vi. It then uses this reference in a loop and continually polls the property FrontPanel.IsFrontmost to determine if the front panel of subvi1.vi is frontmost. When it is frontmost, it performs certain actions. When it isn't frontmost - it doesn't.

This all works great in the development environment, but as soon as I build this 'scenario' into an application I get the following error:

subvi2.vi is generating the reference to subvi1.vi using the string "subvi1.vi" as an input to the path terminal of the Open vi Reference function. Why does this cause problems in a built executable?

P.S. Clearly this scenario is actually a part of my much bigger project, hence I don't have any simple vi's to attach

Message Edited by Thoric on 04-27-2009 01:06 PM

Re: open vi reference by string in executable

Ben — Mon, 27 Apr 2009 12:39:41 GMT

The "string" method of naming a VI only works if the VI is already in memory. I would throw in two indicators to help narron this down. For VI1 (that shows it FP), shows its complete path on the FP when in the exe to figure out if name mangiling is happening. In VI2 add a pop-up that hsows you error coluster after you attempt to open the ref to VI1.

Two other things that could be happening (not sure yet) are if the new VI is opening in the same context as VI1 and VI Server setting to allow opening the ref to vi1.

Just trying to help,

Ben

Message Edited by Ben on 04-27-2009 07:39 AM

Re: open vi reference by string in executable

Norbert_B — Mon, 27 Apr 2009 12:40:25 GMT

Thoric,

it's disturbing that LV is crashing on your system due to this error. What version of LV do you use?

LV 8.6.1 at least (i don't know which version was the first one) creates the following error:

LabVIEW: Open VI Reference no longer matches VIs in memory by filename. A filename is no longer sufficient because the full name of a VI now includes any owning libraries.

This error occurs even in the developement system.

I asume that the crash itself is created by handling of invalid references.

hope this helps,

Norbert

Re: open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 12:45:59 GMT

Hi Ben,

Thanks for suggestions - however I'm having a little trouble implementing them:

I would throw in two indicators to help narron this down. For VI1 (that shows it FP), shows its complete path on the FP when in the exe to figure out if name mangiling is happening. In VI2 add a pop-up that hsows you error coluster after you attempt to open the ref to VI1.

Unfortunately, the crash occurs before the front panel of subvi1.vi appears, and before subvi2.vi runs, therefore I cannot see the result of a path indicator on subvi1.vi nor an error cluster/dialogue in subvi2.vi.

Two other things that could be happening (not sure yet) are if the new VI is opening in the same context as VI1 and VI Server setting to allow opening the ref to vi1.

Not sure what you mean here Ben, can you elucidate a little for me please?

Re: open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 12:50:32 GMT

Norbert B wrote:
Thoric,

it's disturbing that LV is crashing on your system due to this error. What version of LV do you use?
LV 8.6.1 at least (i don't know which version was the first one) creates the following error:
LabVIEW: Open VI Reference no longer matches VIs in memory by filename. A filename is no longer sufficient because the full name of a VI now includes any owning libraries.
This error occurs even in the developement system.
I asume that the crash itself is created by handling of invalid references.

hope this helps,
Norbert

Norbert,

I am using LV 8.6 (not 8.6.1). I am using strings to identify vis, not paths. I believe the error you are encountering only relates to using paths for referencing vis.

If your assumption is correct and my crash is due the handling of invalid references, then I need to generate a path to the vi, rather then using it's name. But generating a full (non-relative) path might be tricky? If within subvi2.vi I use the 'current vi's path' function and strip it to determine the executable path, then add subvi1.vi, should that get me the path to subvi1?

Re: open vi reference by string in executable

Ben — Mon, 27 Apr 2009 12:56:53 GMT

Hi Thoric,

THe issue may be realted to not being able to run and show VI1 now that I read that added info. In that case put up some indicators around launching VI to show the error cluster from trying to launch and open it.

RE: my goobly-gook...

Multiple LV exe can run side by side because they run in different contexts (OS memory space is unique to that app). If you look at the inputs of the Open VI ref you will see that you can dictate which context it will open the VI in. VI server also comes into play as well in an exe so this is where the error code (if any) from trying to open and load VI1 can help us out.

Ben

Re: open vi reference by string in executable

Ben — Mon, 27 Apr 2009 13:01:04 GMT

Thoric wrote:
Norbert B wrote:
Thoric,

it's disturbing that LV is crashing on your system due to this error. What version of LV do you use?
LV 8.6.1 at least (i don't know which version was the first one) creates the following error:
LabVIEW: Open VI Reference no longer matches VIs in memory by filename. A filename is no longer sufficient because the full name of a VI now includes any owning libraries.
This error occurs even in the developement system.
I asume that the crash itself is created by handling of invalid references.

hope this helps,
Norbert
Norbert,
I am using LV 8.6 (not 8.6.1). I am using strings to identify vis, not paths. I believe the error you are encountering only relates to using paths for referencing vis.
If your assumption is correct and my crash is due the handling of invalid references, then I need to generate a path to the vi, rather then using it's name. But generating a full (non-relative) path might be tricky? If within subvi2.vi I use the 'current vi's path' function and strip it to determine the executable path, then add subvi1.vi, should that get me the path to subvi1?

THis really depends on how you did your build. If VI1 ends up as dynamic file vs part of the app, the paths will be different. Easy enough to check. Look at where your exe is and figure out if VI1 is there in the support/dynamics. If not it is probably inside the exe to the path would then be "My.exe.VI1.vi".

But I am speculating thats the issue so try to get more info.

Ben

Re: open vi reference by string in executable

Norbert_B — Mon, 27 Apr 2009 13:05:14 GMT

Thoric,

changing the VI's name to the (absolute/relative) path is definetly something you should try.

You are correct, in my test i used a path-constant where i simply inserted the name of the VI (without it's relative path).

After changing the path-constant into a string one (wihtout changing the content), i receive the following error:

LabVIEW: The VI is not in memory.

To load a VI into memory with the Open VI Reference function, a path must be wired for the VI Path input.

So in either case, you have to work with a path. In your developement system it only works if you opened your subVI before, hence you have it already in memory.

hope this helps,

Norbert

Re: open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 13:11:41 GMT

I played around a little bit more, and tried using filepaths and got exactly the same error.

Then I removed all the code relating to VI server - and still got the crash. That got my suspicions up, so I back-tracked a few versions and have tracked the error down to subvi2.vi attempting to show it's front panel !?

Normally, subvi2.vi does not need to show it's front panel, so "show front panel when loaded" is not checked in its vi properties. During this testing phase, I've been trying to show the front panel for debugging purposes and that's what has been causing the Windows error !

But why simply showing a front panel should cause such a major crash is peculiar - am I missing something here?

Re: open vi reference by string in executable

Ben — Mon, 27 Apr 2009 13:14:36 GMT

Thoric wrote:
I played around a little bit more, and tried using filepaths and got exactly the same error.

Then I removed all the code relating to VI server - and still got the crash. That got my suspicions up, so I back-tracked a few versions and have tracked the error down to subvi2.vi attempting to show it's front panel !?
Normally, subvi2.vi does not need to show it's front panel, so "show front panel when loaded" is not checked in its vi properties. During this testing phase, I've been trying to show the front panel for debugging purposes and that's what has been causing the Windows error !

But why simply showing a front panel should cause such a major crash is peculiar - am I missing something here?

Checking that option force the builder to include the FP. I would not be suprised if the crash is due to not haveing a FP to show.

I sure hope I'm helping more than I am hurting!

Ben

Re: open vi reference by string in executable

Norbert_B — Mon, 27 Apr 2009 13:17:57 GMT

Thoric,

you set the option"Show frontpanel when called" in the VI settings ofsubvi2?

If so, i would expect some controls/indicators which corrupt the frontpanel of subvi2. Could you post subvi2?

hope this helps,

Norbert

Re: open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 13:23:59 GMT

Hi Ben,

Sorry for the confusion, what I meant to say was:

Normally, "show front panel when loaded" is not checked, but for the purposes of this testing phase I have had "show front panel when loaded" checked to show the front panel. This seems to be what is causing the problem for me. When checked I get the crash, when unchecked (and clearly there's no front panel in this case) the code runs ok

Still, I wonder why I get the crash when it is checked?

Re: open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 13:29:32 GMT

you set the option"Show frontpanel when called" in the VI settings ofsubvi2?

Yes, I do, and that's when I start seeing this crash.

If so, i would expect some controls/indicators which corrupt the frontpanel of subvi2. Could you post subvi2?

Corrupt controls/indicators? I hate it when this happens! All too often these days too it seems...

I've posted the subvi (it's actually called Log on keypress service.vi). As I mentioned in my first post, I've been describing but a small portion of my much larger project. This subvi is meant to send user-events to subvi1.vi when certain key-presses are detected, via a type-defined event cluster reference control called Inter-code event cluster ref. Apart from this control, there are only two boolean indicators and the standard error in and out clusters. Please take a look and let me know if there's anything here that could be 'corrupted'.

Thanks

Re: open vi reference by string in executable

Norbert_B — Mon, 27 Apr 2009 13:30:49 GMT

Thoric,

what Ben said is absolutly valid and a possible reason:

When LV compiles code for an executable, it removes as much components as possible. The frontpanel is such a component: it is only required if the frontpanel is shown later on. If you accidently remove the frontpanel during the build-process, but try to display it when running the exe, the exe has to crash. The crash does not need a crash similar to the one you are observing, nevertheless, it is possible......

Therefor please doublecheck your build-settings if you remove the frontpanel of "subvi2.VI" during the build-proces...

hope this helps,

Norbert

Re: open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 13:39:54 GMT

Yes, I am aware of how the compiler removes unecessary components, including the front panels of subvis that no longer require them. I do not explicitely disclude the front panel in the application builder, nor do I attempt to programmatically show it during run-time. I've simply been checking and unchecking the "show front panel when loaded" option depending on whether I want to see or not-see the front panel.

The problem in my case seems to be when this option is checked. Here, LabVIEW must be including the frontpanel in the build, and when this subvi is called from the main vi, it then crashes. When the option is unchecked, the application does not attempt to show the subvi's front panel and the application runs through great. Bizarre.

Message Edited by Thoric on 04-27-2009 02:39 PM

Re: open vi reference by string in executable

Norbert_B — Mon, 27 Apr 2009 13:38:00 GMT

Thoric,

the frontpanel of the VI seems ok, if the typedefinition does not mess it up. so if not the frontpanel removal-thing creates the crash, please play around with the setting "Disconnect typedefinitions" in the build script.

hope this helps,

Norbert

Re: open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 13:43:58 GMT

Thanks for the suggestions Norbert,

I tried disconnecting type definitions in the build, but it still crashes.

Out of interest, I kept this option checked in the application builder, but left "show front panel when loaded" unchecked in subvi2.vi. The program still works. It definitely seems to be a front-panel related complication.

Any more suggestions anyone?

Re: open vi reference by string in executable

Thoric — Mon, 27 Apr 2009 13:52:46 GMT

I learned a trick from an NI technical engineer once regarding corrupt vis - drag and drop the block diagram into a blank vi, relink the controls and indicators to the terminal icon and save as a new vi. Replace all calls to the original with the new vi. But it didn't work. Does this failure perhaps indicate there are no corrupt controls/indicators? I don't know, I guess we can't be sure. Just thought I'd mention it anyway.

Still trying to work around this one.....

Message Edited by Thoric on 04-27-2009 02:52 PM

Re: open vi reference by string in executable

Ben — Mon, 27 Apr 2009 13:53:30 GMT

Can you show us the code where you are luanching VI2?

Are you setting the ref before calling?

Ben

Re: open vi reference by string in executable

Norbert_B — Mon, 27 Apr 2009 13:58:21 GMT

Err, something very different is coming to my mind:

You are using the user32.dll, a system dll.

LV should detect this dll as dependency and copy it into the data-folder. This will lead to the crash you are observing. Please delete the user32.dll from the data-folder in your build-folder.

hope this helps,

Norbert