Labview global variable dll

Dear Sir
我的Labview8.5程式中含有global variable，我要做成DLL，給VC使用，請問global variable要如何包進DLL中。
謝謝
已解決！
轉到解決方案。

Hello wcw1224,
可以參考下面的連結
http://forums.ni.com/ni/board/message?board.id=170&requireLogin=False&thread.id=147485
簡單來說，你在VC下不能直接去存取DLL內的Global Variable
只有DLL包含的程式可以存取Global V
你必須撰寫一個程式，來存取你的Global Variable
然後將這個存取程式也包在DLL當中，這樣VC就可以使用這個函數來存取Global Vairable

Similar Messages

How to build labview global variable into dll?And how to use it in vc++ program?

Hi!
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   I think global variable of labview could be useful when realizing the communication betweeb vc thread and labview dll.So I want to ask whether the labview global variable could also be built into dll and use it.Could you please tell me how to realize my idea?
   Thank you!

[email protected] wrote:
Hi!
I want to build labview application into dll and use vc++ to call
it.The labview program is a little complex,for it has many interface to
vc++ and has while loop in it.When I use vc++ to call it,I must use
vc++ to do other things.That is to say,vc++ creates a new thread to
provide for the labview dll to run.the vc main thread goes on to other
things.But the vc++ main thread must communicate with the labview dll
by setting its inputs' parameters and get the results of running
labview dll.Can you advise me how to realize it?
   I
think global variable of labview could be useful when realizing the
communication betweeb vc thread and labview dll.So I want to ask
whether the labview global variable could also be built into dll and
use it.Could you please tell me how to realize my idea?
   Thank you!
You
can't access LabVIEW globals directly from a caller to the LabVIEW DLL.
However there is no problem in providing specific accessor VI functions
to that global and export them as additional functions from the DLL.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Making dll from VI containing labview global variable ?

I've made dll from VI containing labview global variable.
But, when I write a c program calling a function from the dll, it returns just error.
The goal is to read a labview global variables from c program. What can i do for it ?

Hi
If you don't use the dll in your LV app, it will be difficult, because it will be in the adress-range of you c app. So any writing of values to the global variable in LV, won't affect the variable in the dll.
What you can do is some kind of client-server architecture. You need a third app, which just does the data exchange - so you should be able to write a value from LV and read it from c.
There already have been discussions about similar topics - just search the forum.
Thomas
Using LV8.0
Don't be afraid to rate a good answer...

Can LabVIEW global variables be shared between UUT sequence steps in the parallel sequence model?

Sorry for this simple question, I'm having a hard time finding this answer.
If I launch a sequence to run on two UUTs in the parallel sequence module, can I get both UUTs to run LabVIEW vis that use global variables such that :
1) UUT 0 executes 20 LabVIEW Vi steps asynchronously, 5 of which access data from LabVIEW global variables A, B, C (Strings)
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Brad Whaley
LabVIEW Certified Engineer

Hi bdwhaley,
Are your parallel sequences only reading from the global variable? Or are they writing to the variable as well? If it is just reading, then you should be okay. File globals are read from memory. Every time they are read, a copy of the data is made in memory.
Humphrey H.
Applications Engineer
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Can labview globals or controls be modified directly from a dll

Is it possible to obtain a pointer or handle to LabVIEW global variables - specifically clusters of scalars, not including strings or arrays, which presumably would occupy a fixed memory area.
If this is not possible, can the value of data held in LabVIEW controls be modified from a dll by passing control references to the dll and if so how can this be done?
Using LabVIEW 6i, Windows NT SP6, MS-VisualC++ 6.0

I created a dll with LabVIEW 6.0 which had as its only input parameter a control refnum for a string control. I used this refnum to modify the value of the string control. I built the dll and then from a new VI called the dll using a call library function, passed it a refnum to a string control in the calling VI and ran it. The value of the string control in the main VI was change by the dll by only passing it a refnum.
To do this you must have LabVIEW 6.0 Pro or App builder. (I did all this with LabVIEW 6.0.2 update installed)
Attachments:
caller.vi ‏8 KB
chngstring.dll ‏17 KB

Programmatically select global variable object

Hello all.
I have a rookie question that may have an easy answer (or perhaps you can direct me to a different method which is fine too). I’m using a global variable in an instance where it’s controlled by a parent VI and read by multiple children VIs. The global variable contains Boolean switches, each with a specific name.
If possible, I’d like to make the ‘child VI’ more generic and programmatically flexible so that I don’t have unique children. That way, instead of four children, I just have one (makes debugging easier). Here’s the crux of my question: selecting which object is assigned to the global variable on the block diagram is done by clicking on it with the mouse – can I instead do that programmatically?
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Cheers!
Attachments:
ForumEX files.zip ‏31 KB

Steve Chandler wrote:
There is a better way of doing this as the others have already pointed out.
Even Single Process Shared Variables with their API Interface would be better as Globals:
Using this VI to read the variables gives you the ability to reference them with a string (Link to Variable). You may have to add an additional variable in future versions of your code, where you just need to add the new variable to the project and pass the string to the VI without changing the code. Single Process Shared Variables are based on Global Variables, which are usually just a bit faster. Single Process Variables can easily be converted to network variables.
However, I agree with Damien that Data Value References would probably be the best sulution.
Btw, there is a good KB talking about Globals: Are LabVIEW Global Variables good or bad, and when is it ok to use them?
Christian

Call function in LabView from a DLL, then access global variable from DLL

I have created a DLL in LabWindows with a function and a structure. I want to call the function from within LabView and then access the global structure. I am able to call the function from the DLL with a "Call Library Function Node" and can access the return value, but I cannot figure out how to access the global structure. The structure is declared in the DLL header file with __declspec(dllimport) struct parameters.
Is there any way of accessing this structure without using the Network Variable Library?
Solved!
Go to Solution.

dblok wrote:
When you say "access to" or "the address of" the global variable, do you mean to pass the variable as an argument to the function call in the DLL? If so, then I was not really sure how to pass a cluster from LabView by using the "Call Library Function Node".
Yes, that's exactly right. I would include a pair of helper functions in the DLL to read and write the global variable. Alternatively you might write separate helper functions for each field inside the global structure, depending on the number of fields and whether you want to do any validation on the values.
You can pass a cluster by reference to a function that expects a struct by setting the parameter to Adapt to Type, so long as the cluster does not contain any variable-length elements (strings or arrays). The cluster needs to match the struct exactly, and sometimes that involves adding extra padding bytes to make the alignment work. Variable-length elements in LabVIEW need to be converted to clusters containing the same number of elements as the struct definition (for example, if your struct contains char name[12], you would create a cluster of 8 U8 values, and you could use String to Array of Bytes followed by Array to Cluster to convert a LabVIEW string into that format). If the struct contains pointers it gets more complicated, and it may be easier to write functions in the DLL to access those specific elements individually.
If you can't get this working or need help, post your code and an explanation of the error or problem you're seeing.
EDIT: it is also possible to include a single function in the DLL that returns the address of the global variable, which LabVIEW can then use to access and modify the data, but that's more complicated and likely to lead to crashes if you don't get the memory addressing exactly right.

How can I handle global variables from different DLLs created based on VIs that access those variables

My goal is to break apart an entirely LabView created application so I can still use parts of it (builded as Shared DLLs upon on some VIs) in my new .Net application. My problem is that some others VIs (that I am not intending using) are changing those global variables (in the natural data flow of the application). I could , of course, send the values of those global variables as parameters, but I don't know how should I pass those data types (and their size)... There are some clusters there...
Any help is well appreciated

vulpe wrote:
My goal is to break apart an
entirely LabView created application so I can still use parts of it
(builded as Shared DLLs upon on some VIs) in my new .Net application.
My problem is that some others VIs (that I am not intending using) are
changing those global variables (in the natural data flow of the
application). I could , of course, send the values of those
global variables as parameters, but I don't know how should I pass
those data types (and their size)... There are some clusters there...
Any help is well appreciated
Your
problem is of course the use of globals. That is almost always a bad
idea and asking for troubles once your application gets bigger.
Avoiding race conditions and undesired influences between different
parts of your application will take up more and more of your
development time as your project grows.
You should look into Functional Globals (LV2 style globals) and shift
registers for data storage and queues for passing information between
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will allow you to grow your application without increasing the
complexity of managing such things exponentially.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Problem with .DLL and global variables

Hi,
I need some helps to figure out my problem.
I wrote a .dll file to open and run a GUI. When I run it at the first time, it is ok. When I call it again, there is an error "Pointer to free memory passed to library. It will be ok if I completely exit the program that calls the .dll before re-call it. I think there is some problems with global variables when I call another thread. How can I free global variables between threads. Is there any solution for this problem?
Thanks

Vinh Pham:
Are you doing anything intentionally that frees your globals?
CVI ships with an example program that demonstrates calling a DLL to create a user interface: guidll.cws.
I made two simple modifications to guidll.cws.
1. In guidll.c, I made hpanel global by moving its declaration from RunDLLUI() to right below the #include statements.
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I built the project and ran it. I had no problems with free'ed globals.
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Can you either post your code or a modification to guidll that demonstrates the problem you're having?

How to get the value of the global variable of test stand in labview User interface?

Hi.
Can anyone Please share examples and tell me to how access the test stand global variable using labview user interface.
Solved!
Go to Solution.

I'm not surprised that what you are doing doesn't work. The Start Execution UI Message is triggered when the user clicks a button to start an execution. Realize that most executions go through a process model. So you could be looking at the sequence context of the process model and not your client sequence file.
I recommend reading that link I posted above. UI Messages are your best bet but you cannot just piggy back on an existing UI Message like this. They may not be getting sent at the time you need them to be. The only way to ensure you get what you want is to trigger one yourself at the right time.
Regards,
jigg
CTA, CLA
teststandhelp.com
~Will work for kudos and/or BBQ~

Why does Labview create a .vi for each global variables?

Hello,
I wrote an Labview application which use several global variables (almost 30 variables). All the variables are of variable type "single process". For each of these variables, Labview creates a vi.
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Cheers,
Risotto

Hi everybody,
Thank you for your answers, I get a lot of informations.
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I will have a look on the tutorial too.
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I use several library in the project explorer. But the library in the project explorer seems to create file with other extension (.lvlib) than the sdtandard LabVIEW library (.llb).
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Attachments:
picture.jpg ‏223 KB

How do I load a vi of global variables whenever LabView opens?

I want to be able to load a VI with Global Variables whenever I open Labview, and not have it open dynamically. So in short, how do I bind or attach a VI to open every time LabView opens and starts up.

Look at this KnowledgeBase article:
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/44e99cc41aa39f538625694b005679c0?OpenDocument

Sharing a Global variable between two Labview applications

Hello,
A.exe and B.exe created by Labview 8.21. Both A.exe and B.exe run on the same PC. A and B exchanges data through a Global variable. Everything goes well if I launch both VI in Labview but when I try to launch the built executables A.exe and B.exe I get an error 1059. In B.exe I just use the Open Reference.vi icon to which I connect the path of the other application (A.exe) that already runs.
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Thanks for any hint,
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With a user ID# of 298, you have been using LV for quite a while.
Review the release notes for LV 8.0 LV 8.2 etc and you will see that that two different exe's run in different contexts.
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Ben
Message Edited by Ben on 01-15-2008 12:50 PM
Ben Rayner
I am currently active on.. MainStream Preppers
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Labview 8.0 PDA local & global variable cause a crash

I've attached a pic of the portion of the VI that causes the PDA
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accessing the variable
this way causes it to crash .. Any help would be greatly appreciated.
Message Edited by GHernandez on 02-09-2006 06:25 PM
Attachments:
Problems.jpg ‏162 KB

I've re-written this application , where i have not included global
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executes for maybe a min or 2 then crashes giving me the
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App failed. Error code 560331006. Bad input argument to function.
unfortunately, this error code does not tell me anything.
Message Edited by GHernandez on 02-10-2006 04:51 PM
Message Edited by GHernandez on 02-10-2006 04:52 PM
Attachments:
problema.jpg ‏158 KB

How can I run two different vi's in same project which are accessing same global variable with out effecting the speed of the execution of both the vi's

Hi
I have build an Labview project with FPGA target . I have configured an FPGA VI and an host Vi to acquire data and logged the data to a file and stored the latest data in a global variable simultanously. I have configured one more VI in the same project to access the global variable. I have build a dll to access both the VI as functions in LabWindows/CVI code. My task in CVI is to update configured GUI with latest data periodically and run the host VI continously for a long time and log the data to a file. GUI should update for every one second with latest data for this I am using the second VI in which I am accessing the global varibale in which the latest data has been stored in host VI.

Duplicate Post (go here)

Labview global variable dll

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