Function Prototype calling dll

Is there any way to automatically import the function prototype using
LabVIEW Call Library Function??
It is very boring write every time the function prototype.....
Thank You
Alessio Colzi

Al S,
that's only the half truth for the question. You can see the function names but the protoype will always be void (void); if you do not have a include file in the same directory (Tested with shell32.dll).
With a DLL created by MS Visual C++ with the include (*.h), export library (*.exp) and library (*.lib) in the same folder I also get only the function names and no correct prototypes.
With a DLL created with LabVIEW and the include file in the folder I get the function names and the correct prototypes.
Waldemar
Waldemar
Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
Don't forget to give Kudos to good answers and/or questions

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Calling DLL function using LabVIEW 7.1?

Here's the scinario:
I have LabVIEW 7.1 and i'm trying to call a DLL function using 'CALL LIBRARY FUNCTION NODE'.
I have used this in the past with no problem. But right now, when I use this node and link it to the
library and function name, i get 'ERROR loading Dllname.dll' message.
NOTE that the DLL is generated using VStudio2003 or VStudio.NET. Could this be a problem??
Also, i noticed that there are some JUNK characters before & after the function name that show
up in function prototype:
long ?EcpvsSign@@YAHHPBEH0HPAE1@Z(long Signer, CStr NonRMsg, long NonRMsgLen,
CStr RMsg, long RMsgLen, CStr SigR, CStr SigS);

tbd wrote:
Hi rkpat,
You might check-out this thread on building WIN32 DLLs - expecially the bit re: "mangles names" under the paragraph titled "C Language Source File". My recollection is that 'extern "C"' directive in the header file for the DLL solved the name-mangling problem, but it's been a few years!
Cheers!
Message Edited by tbd on 03-01-2007 11:19 PM
tbd is right. You have to first disable name mangling as it creates all kind of troubles. Other issues might be that your Visual Studio 2003 or .Net edition links in dynamic runtime libraries that are not standard available on every Windows PC so that you need to redistribute the according runtime library installer together with your app for the DLL to be even loadable.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Call function from C++ (dll file) in Flex

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i using Adobe Flash Builder with Flex 4 , i write a C++ Code in dll File , i need to access to my Function in dll file in Flex ?? what should i do ??

Lets make sure you are performing the correct actions:
1. Place a Call Library Function node on your block diagram.
2. Double click the node to open up the Call Library Function dialog box.
3. Click the Browse button and navigate to the DLL function. Select the proper DLL and click Open, or just double click on DLL.
4. On the Function Name box, click on down arrow. A list of functions found in the DLL should be displayed. Choose the function.
5. On the Calling Conventions box, click on down arrow and select C or WINAPI. In your case, it should probably be C.
6. The Parameter box should show return type. In the Type box, select the data type of the return value. Since you won't see HRESULT here, you need to find out what data type HRESULT is in the C code. I would guess it is a numeric so select numeric from the drop down list.
7. Click the Add a Parameter After button.
8. In the Parameter box, change the name arg1 to the actual name of your first parameter, which is byPortNumber.
9. In the Type box, choose Numeric, since a BYTE is a numeric in Labview.
10. In the Data Type box, choose Unsigned 8-bit Integer, since a BYTE is a U8 in Labview.
11. In the Pass box, choose Value. If the C parameter was a pointer (*BYTE), you would choose Pointer to Value.
12. Verify that the contents of the Function Prototype box contains the correct syntax according to the C declaration.
C: HRESULT RSPInitComm (BYTE byPortNumber) should be in Labview: long RSPInitComm(Unsigned char byPortNumber)
13. Click OK button.
Try it out.
If you get a crash, change the Calling Convention to WINAPI.
- tbob
Inventor of the WORM Global

Call dll function on Windows CE6.0 Device

I am trying to call a dll on a windows CE6.0 device, which is the KEBA KeTop T20techno.
In the "call library function" I added a selfmade WIN32 stub dll and in the build specifications I added the original Windows CE .lib file.
When I try to build an execution I always get the following build error:
THUMB is a missing VI or C file
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Can anyone give me a hand on this issue?

Hi Oimel,
Are you sure that the function name and function prototype for both libraries is the same?
Thanks as kudos only

Call Library Function "Function prototype" incorrect

Why does the same DLL file produce difference function prototypes?
I inserted the call library function node in my VI directly. However it has the incorrect function prototype.
This call library function node I copied from the “Goodness of Fit.vi”. This has the correct function prototype.
Solved!
Go to Solution.

The DLL file DOES NOT produce prototypes at all. That is up to you! Look at the parameters tab for both of your examples, you will see that for the second one, someone has already filled in the prototype information. When making a new DLL call, you will need to know the correct prototype to apply, this is usually obtained from the .h (header) file.
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Architecture is art with rules.
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Calling a function from a DLL, exectution in background mode.

Dear Experts,
We have created an ABAP report the calls a function from a DLL file. If the report is executed in on-line mode the program calls and executes the function from the DLL, but if the ABAP programa is executed in background mode it doesnt calls the DLL function.
Do you know a way to solve the problem when executing in background mode?
Best regards.
Antonio

Hi Gabriel,
Let me explain in details about my DLL function.
We are importing the business partners from legacy system into the SAP CRM system, so at the moment we created the BP master data via BAPI, I get the name of the BP and this moment I call the function in the DLL file. I export the parameter name and I receive back a simplified string with the name reduced to a code. This code I get back from the dll it is insert in a Z table, so there is no interaction in the screen, all must be executed in background mode, because there are a lot of business partners to be converted in SAP system.
I am sending my code for your considerations.
Instancia a DLL
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IF sy-subrc NE 0.
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ENDIF.
Move para a tabela interna IT_NAME os valores recebidos na TI_NAME
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         wa_matchcode-zparmcfn
         v_empty
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Using call library function on a dll file created in an old version of labview

So I'm trying to update an old labview program to work in labview 2012. Everything converted over just fine but labview will always crashoverwrote some while using a library function in a DLL that was compiled using labview 8.5. Labview exits, stating that it vital memory area. It passes an array of data to the library call and an empty array for output. I thought I could get around this problem by changing my code to initialize the array being passed in so that it would be large enough to hold all the expected output. Now instead of overwritting areas of memory it shouldn't, I get a pop up message that says:
fatal internal error
memorymanager.cpp line 406
8.5.1.f5
So it appears because I don't have the ability to recompile the DLL file it runs off of the 8.5 runtime instead of the more recent one. Is there any thing I can do about this?

rjpierce wrote:
So I've been trying to figure out a way around this on my own while waiting on a response. From what I'm reading, a dll created in one version of the labview runtime can't be used by a different labview runtime. Am I correct in this? I feel like I must be mistaken since that's basically the opposite of how a dll should work. If nothing else works I have access to the original code for the DLL but it requires the control and simulation toolkit. I would like to avoid having to recompile the DLL since it was put in to a DLL to avoid the need for the toolkit to begin with.
Your problem most likely is that you try to pass native datatypes to the DLL function? That only can work if the caller and callee use the same LabVIEW runtime engine. Otherwise the memory block created in the memory manager of the caller will be accessed by the memory manager in the callee and bad things happen. Instead you should define the DLL function to use standard C datatypes (Pointer to C array) and also make sure to allocate the according buffer in the caller for all output array parameters.
An even more elegant way would be to completely abandon the DLL approach and call the according functions directly in LabVIEW. Then you won't have the problems about mismatched runtime engines. Passing C array pointers to a DLL is less performant than passing native datatypes, but if you use native datatypes you have to make sure the DLL is compiled in the same LabVIEW version as the one you call it from.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Can I call a function from a dll in LabVIEW that returns:double*string and int.?

I have a function from a dll that return a double* string and an integer. How can I call this function from LabVIEW? There is a possibility to work in LabVIEW with a double* string?

pcbv wrote:
> Hello all, The header of the function is:
>
> "HRESULT WRAPIEnumerateDevices(WRAPI_NDIS_DEVICE **ppDeviceList, long *plItems);"
>
> where WRAPI_NDIS_DEVICE have this form:
>
> typedef struct WRAPI_NDIS_DEVICE { 
> WCHAR *pDeviceName; 
> WCHAR *pDeviceDescription; }
> WRAPI_NDIS_DEVICE; 
>
> The function is from WRAPI.dll, used for communication with wireless card.
> For my application I need to call in LabVIEW this function.
Two difficulties I can see with this.
First the application seems to allocate the array of references
internally and return a pointer to that array. In that case there must
be another function which then deallocates that array again.
Then you would need to setup the function call to have a pointer to an
int32 number for the deviceList parameter and another pointer to int32
one for the plItems parameter.
Then create another function in your DLL similar to this:
HRESULT WRAPIEnumExtractDevice(WRAPI_NDIS_DEVICE *lpDeviceList, long i,
CHAR lpszDeviceName, LONG lenDeviceName,
CHAR lpszDeviceDesc, LONG lenDeviceDesc)
if (!lpDeviceList)
return ERROR_INV_PARAMETER;
if (lpDeviceList[i].pDeviceName)
WideCharToMultiByte(CP_ACP, 0,
pDeviceList[i].pDeviceName, -1,
lpszDeviceName, lenDeviceName,
NULL, NULL);
if (lpDeviceList[i].pDeviceName)
WideCharToMultiByte(CP_ACP, 0,
pDeviceList[i].pDeviceDescription, -1,
lpszDeviceDesc, lenDeviceDesc,
NULL, NULL);
return NO_ERROR;
Pass the int32 you got from the first parameter of the previous call as
a simple int32 passed by value to this function (and make sure you don't
call this function with a higher index than (plItems - 1) returned from
the first function.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

How to call external functions without a .DLL (just using a .H and .LIB file)?

Hello everyone,
actually I'm facing little difficulties on how to get an external function getting called from within CVI (Version 2009).
I was supplied with a .H file and a .LIB file to call an external function from within my CVI project. The .H file looks like this:
void exportedFunction(double *parameter);
As far as I know, the external function was written with MS Visual C++ 6.
So I tried to statically link to the extern al function like this:
- Add the .H file and the .LIB file to the CVI project
- #include the .H file where I needed to call the external function
- do the external function call
When building I get an unresolved external function call error from CVI so this seems not to be working.
I made some searches around and got up with two possible issues. Maybe one of you can help me get a bit further and get things working.
1) The "real" function code is located in the DLL file which was not delivered to me. Or is there a way to get things done (call external functions) just with a .H and a .LIB file (without any .DLL file included)?
2) The external function does not export according to "C-Style" rules. The function signature in the .H file shows no things like
extern "C" __declspec(dllexport) void __stdcall ...
Or maybe it's a combination of both issues (missing .DLL + wrong export style of function)?
I guess I could get around the wrong export style of the function when I manage to write a wrapper around the original function that actually uses C-Style exporting. But I guess I need the .DLL file for this try as well.
Thank you for your answers.
Best regards,
Bernd
Solved!
Go to Solution.

There is no need for the dllexport stuff. There is also the option for a static library without any DLL. But the 'extern "C"' is essential, because it forces the C++ compiler, which was probably used to compile the library , to use C calling convention.
If you can't ask the provider of the library to provide a version which was compiled using C calling convention the way to go is to write a wrapper with VC++6 around that library which reexports the functions using C calling convertion. Something like
extern "C" type0 myfunc1(type1 arg1, ...) {
return func1( arg1,...);
for every function , you need to use.
BTW. "unresolved symbol" is the linker error message, you can expect if you try to link C code against a library build with C++ calling convention.

Calling Functions of Loading DLL using java

I have a dll file
I know the functions which are ther in the dll
But how to call those functions using JAVA ?
can anyone tell me how to do the same...
Thanx in advance
regards,
Ritesh

I assume that you have a regular DLL and that the functions in that DLL are exported and that you know the signatures of each function.
With that in mind, you will need to use the Java Native Interface (JNI), to call those functions from Java. In a nutshell, you will need to create at least one class which declares some native methods, code a class static code block to load the JNI-DLL you are about to create, compile the class(es), run the javah tool supplied with the JDK which will emit a C compatible header file, implement the functions from the generated header file and compile that source file to into a DLL. It would be in this DLL that you would use the functions in the DLL that you ultimately want to access. So, what you wind up doing is creating a wrapper DLL.
Take a look at the JNI tutorial trail from Sun at http://java.sun.com/docs/books/tutorial/native1.1/index.html.

Calling C Functions in existing DLL's from Java

Hi Guys ,
The tutorial in this site talks about creating ur own DLL's and then calling them from Java . I need to call C functions in existing DLL's from Java . How do I go about doing this ? . Any help on this would be much appreciated.
regards
murali

What you are interested in can be done with what's called "shared stubs", from the JNI book (http://java.sun.com/products/jdk/faq/jnifaq.html), although you don't need the book to do it (I didn't).
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If you can limit yourself to functions to a single function signature (number and types of parameters), or at least a small set that you know you'll call at compile time, you can modify the example so that the assembly language part isn't needed, just straight C code.
Then you'll have one C library that you compile and a set of Java classes and you can load arbitrary functions out of arbitrary dynamic libraries. In my case you don't even have to know what the libraries and functions are ahead of time, the user can set that up in a config file.
You mentioned doing this with Delphi. One thing to watch out for is C versus Pascal (Win32) function calling convention. A good rule of thumb; if it crashes hard, you probably picked the wrong one, try the other. :-)

Error 1097 after calling dll function which allocates memory inside

Hello!
When a call one my functions in my dll from LabView, i get an error 1097. My function takes a few arguments and then allocates some memory for measurement.
It's not returning any pointers to that memory area, it is just allocates that memory for itself. I don't know what could be the problem, probably i am missing something.
Could you help please?
Best regards,
Tamas
Solved!
Go to Solution.

Are you sure that the allocate function is the problem?
Error 1097 simply means something inside the external code wrote into memory locations that it was not meant to write. That is usually because of output buffer parameters that are not allocated (large enough) in LabVIEW when passed to the external code fucntion, so the function assuming it received a buffer of a certain size happily writes into that buffer but overwriting other information it should not have.
But that is by far not the only possibility to cause this error. A simple bug in the external code can cause the same problem when a pointer goes astray or such. The fact that you used that library elsewhere already without seeing any problem is unfortunately no guarantee that the function is not buggy. The LabVIEW exeception handling around the Call Library Node has gotten rather picky and can detect violations that do not have to cause visible problems at all. But the violations it detects are real violations so just silencing them is not a good idea, as they could cause all kinds of problems including overwriting vital data structures in your program that either cause a crash later on or simply wrong results in other parts of your program. Especially the last one is a total bummer to debug.
Without seeing much more of your code it is basically impossible to point out where the problem could lie. The particular Allocate function doesn't look like there is much that could be done wrong, but I would assume that you call several other functions too somewhere, which could cause the problem. If you can absolutely positively say that you never ever call any library function with a to short (or unallocated) buffer parameter, then you will have to take it up with the manufacturer of your lib, as it would seem very likely that there is some problem in there.
Also you pass a handle to the library function but your Allocate function does not have this as a parameter! Where does this handle come from? Are you sure you have allocated and prepared it properly before calling this function? A handle is quite often a pointer, although usually a so called opaque pointer meaning the user of the library does not and should not know anything about the structure this pointer points to. It is only known internal to the library.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Call a special function in the dll using Call Library Function Node????

Dear all,
I am calling a special function in the dll using call library function node. There is a input parameter that it is a enum type in this function. I don't know how to deal this parameter for calling this function.Has anybody solved this problem?Please advise!
I am appreciated of you anytime.

Most of the times an enum is just a U8/U16/U32, internally so probably you can call it with just a U8/U16/U32 or something. For the correct value you have to look at the definition.
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Call multiple functions from same dll with call library function

hi,
i am working on a project in wich we need to make a UI to read out a sensor network.
the UI should be usable in any project, but every node needs a different piece of code depending on the type of sensor with wich it is equipt.
so i need to be able to call different pieces of code when i need them, and still be able to use the UI in future projects with possibly new types of node we now don't have.
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but i have never worked with DLL's (just learned about this option 3 day's ago) so i have a question.
i know i can dynamicly change the DLL i call with the call library function, but can i dynamicly change the function i call from that DLL ?
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kind regards,
stijn

nazarim wrote:
ok so there is no (easy and ubderstandable) way for me to dynamicly change wich function i want to call from a certain DLL.
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Thepath on the Call Library Node can be used to load a different DLL. Obviously since you can't change the function name your other DLL would have to export exactly the same function name and of course with the same parameters. This is seldom the case so it is not the main use of the path input to the Call Library Node. It's main use is as indicated to load DLLs at runtime rather than at load time of a VI. So that an application can run even when the DLL is missing, until the moment the functionality from that DLL is needed.
If you can make sure that all your DLLs export the same function name with the same parameter you can use the Call Library Node to call into different DLLs through the path input. If however you would need to call different function names you would have to resolve to some DLL which does do the dispatching and invocation using LoadLibrary() and GetProcAddress(). But unless you need to go with DLLs for some reason using the Call By Reference Node can give you an even more flexible approach.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Calling a function from a dll written by using visual studio c++

Hi, how can i call a function from a dll which is written by visual studio c++ in test stand? Although the functions in dll are exported and i've chosen c/c++ adapter, i saw no function in test stand. Is there a different step while i'm calling a function from a dll written by c++ than calling a function from a dll written by cvi?

Hey Sadik,
Selecting the C/C++ DLL Adapter Module should be sufficient for this. When you drag an action step for this onto the Main Step and navigate to the location of the DLL, the function list should populate and you should be able to select the function you want to use. If this is not the case, would you be able to post this DLL so that we can test this on our end?
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Function Prototype calling dll

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