Calling external C-functions in DLLs with struct as parameters

Hi all PL/SQL Gurus !
Is it possible to call external functions in a DLL written in C
wich has pointers to C-structs as parameter. Can you point me to
an example or extended documentation about this. I had a look at
the Oracle doc's but found no examples about structs.
Thank you very much,
Stefan.
P.S.: Konfiguration: Oracle 8.1.7.0.0 Client and Server on W2K-
SP2 machines.

Hi,
I have the same problem with you.Now,have you resolve the problem?
I want to know how to do.if you resolve it ,could you give me a example.
thanks .
best regards!
Liyf

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Call a Borland Delphi DLL with Structs from LabView

Hello,
I have a problem to build an equivalent Struct in Labview to the following Struct which I want to retrieve from a DLL.
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TM2DScanline=record
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Are raster and maxScans both constant? If I recall correctly, many dialects of Pascal just lay the elements of a fixed-size array out in memory with no size parameter; if this is the case with Delphi, then you may be able to do the following (in my example, I'll assume "raster" is a constant set to 40, and maxScans is a constant set to 5):
Create a cluster called XWert with 40 Numeric elements (representation: DBL).
Copy XWert and name the copy ZWert.
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Create a Numeric inside TM2DScanline called YWert (representation: DBL).
Drag XWert, then ZWert, then IWert into TMD2Scanline.
Create a cluster called ScanArea and drag 5 copies of TMD2Scanline into it.
Create a Call Library node on your block diagram, give it your DLL and function name, and set the return value to whatever your Delphi function returns. You probably want the WINAPI calling convention.
Add a parameter and make it "Adapt to Type: Pointers to Handles". Close the node and wire the ScanArea cluster to the input.
Right-click on the Call Library Node and select "Create .c file...." Read through the C file to make sure its structure is similar to your Delphi record: you should see five copies of the TM2DScanline structure, each of which contains a double followed by two fixed 40-element structures of double and a fixed 40-element structure of unsigned char. You should see no reference to the word "Hdl" anywhere in the code.
This strategy will only work if the arrays in your records are fixed at a constant size, and if Delphi lays out the arrays in memory as described above. Instead of doing all this work, you may want to write a small C or Pascal wrapper around your Delphi function. This wrapper could take simpler parameter types (which are easier to use from LabVIEW) and bundle them into the cluster before calling your Delphi function.

How to use Call library function node for a function in dll with VOID data type

Hi All,
I would like to ask for your kind help,
I am facing an issue with the call library node.
I have a C++ function(stdcall), which has void as data type
error code XXXX(hwnd, lID, getValue, *void data1, *void data2)
the data1 and data2 types are always changing depending upoin the value of "getValue".
Primarily i can use call library node multiple times and adapt each node according to the data types of data1 and data2, and extract the values and use in the code. Here is no issue. Real question is:
My question:
How can i just use one time call library node and make a case depending upon the "getvalue", which will control the data type of data1 and data2. Here i really looking for solutions.
My trials:
i used varaints as input to the call libray node for data1 and data2, and selected Parameters in call libraby node as " Adapt to type". here labview just crashed.
i really appreciate your feedbackand suggestions.
Thanks
Kutbuddin
Solved!
Go to Solution.
Attachments:
Clipboard02.jpg ‏103 KB

A variant is a very specific LabVIEW datatype (really a C++ type object internally) and trying to pass that to a function, which excepts a flat memory pointer there, for sure will crash very quickly.
As to endianess, yes Unflatten will be able to adjust for endianess, which in this case however is most likely exectly NOT what you want. So make sure that the you select native type for the endianess input on Unflatten from String. LabVIEW internally works with whatever is the native endianess, as will most likely your C++ DLL. The platform independent big endian format does only come into play when you receive data streams over some streaming interface like a network connection. Here it is desirable to use an endian format that is independent from the actual platform that generates and consumes the data stream. LabVIEWs default endianes is big endian here.
But as long as you pass data directly to native components like DLLs there is no difference in endianess between what LabVIEW uses and what those components use.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Having problem with calling external javascript functions in LV

Hi,
I found this VI: http://lavag.org/topic/10304-discuss-calling-external-javascript/, which I believe can be really helpful for my work. The problem is I can't get it to run based on the following problem:
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Hi,
To start I am using this examplo from the google code page.
<!DOCTYPE html "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
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</head>
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</body>
</html>
It loads a basic map, and is saved in a html file created for example in Notepad. Basically as I said the VI is very simple, see next image.
But like I said, this strategy does not allow labview to interface dinamically with the javasscript code in the html file. Doing it this way, I would have to constantly update the code in the file with new coordinates and loading the map again. This causes the mentioned flickering problem that I also had with static maps.
Diogo

Error while calling external library functions

Using visual studio I wrote the following code test javascript communication with external C/C++ libraries:
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extern "C" __declspec(dllexport) double AddNumbers(void);
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return a + b;
long ESGetVersion (void){
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It seems to me that it loaded successfully due to the output I am getting from the second statement. But I am getting error at the third statement where I called AddNumbers(10,20) function.
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I have the same problem. This is my code:
extern "C" __declspec(dllexport) char* ESInitialize (TaggedData* argv, long argc);
extern "C" __declspec(dllexport) long ESGetVersion (void );
extern "C" __declspec(dllexport) void ESFreeMem (void* p);
extern "C" __declspec(dllexport) void ESTerminate (void );
extern "C" __declspec(dllexport) int AddNumbers(int a, int b);
extern "C" __declspec(dllexport) char* ESInitialize (TaggedData* argv, long argc)
return "AddNumbers_dd";
int AddNumbers(int a, int b)
return a + b;
long ESGetVersion (void){
return 17;
And the code that I wrote in javascript is:
var obj = new ExternalObject("lib: mydll.dll");
var x = obj.AddNumbers(10, 20);
alert(x);
The version of the library is correct, but when I try to use the function "AddNumbers" I receive this error "AddNumbers is not function".
What would be the correct procedure to call a function inside a DLL?

How to call external java functions in XSLT Mapping Programs

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I am unable to call java programs in XSLT MAPPING.
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i wrote the code...
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Calling external DC functions in BPM

Hi, we need to call an external function defined in another DC than the process. The help states this is possible by defining a namespace. Where do I put that namespace declaration? In what file? XSD?
http://help.sap.com/saphelp_nwce711/helpdata/en/c3/fdb196a56b41b38bd7215accabba48/content.htm
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End of the example.
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Just put the ns definition in the expression editor.
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Thanks Benny.

Calling an external C function from a C file in JNI

Hello,
I am trying to call an external C function, from a C file which is being called by a Java file. I am getting an unresolved symbol error. I have tried many things like, making the external C function in the format of JNI, etc, etc. It is still not working. I think it has something to do with linking the two C files. If anyone can please answer this, it would greatly help me. here is the code:
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Now i use the Visual C++ command prompt to compile this by saying:
javac HelloWorld.java
javah -jni HelloWorld
cl -Ic:\Java\jdk1.6.0_20\include -Ic:\Java\jdk1.6.0_20\include\win32 -MD -LD HelloWorld.c -FeHelloWorld.dll
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Nick

Hi,
In your post on velocity review, you did not compile MyOldHello.c. You compiled a C file that included the header file for it and called a method defined in the header. The linker is never going to be able to find the code for this if you do not include the object file for this.
Try this. You will also have to add in any JNI libraries you need to link against but I am sure you could work that out.
cl /c MyOldHello.c
cl /c -Ic:\Java\jdk1.6.0_20\include -Ic:\Java\jdk1.6.0_20\include\win32 -MD HelloWorld.c
cl /LD MyOldHello.obj HelloWorld.obj /FeHelloWorld.dll
[http://msdn.microsoft.com/en-us/library/f35ctcxw(VS.80).aspx]
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How to call external Java code from Animate project?

I am creating a trainer using Animate that needs to interface with an aircraft model written in Java. Is there a way to call external Java functions from Animate?
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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:
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- 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.
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extern "C" __declspec(dllexport) void __stdcall ...
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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.
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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.
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extern "C" type0 myfunc1(type1 arg1, ...) {
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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.

Crash "DAbort 0x37C03D in MemoryManager.cpp" when calling DLL with "Call Library Function Node"

Hi all,
I would like to work with a LabVIEW program that I did not programm by myself.
In this programm an external DLL needs to be called. in the Momente this dll ist called with the "Call Library Dunction Node" LabVIEW crashes with this Error Message:
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Attached is the entire Log.
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Attachments:
lvlog.txt ‏2 KB

A DLL can be compiled by different compilers. By "generic" C DLL, i refer to ANSI C (so no C++, no Borland C or something else).
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Call multiple functions from same dll with call library function

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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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How to call a dll with special parameters in Labview?

Hi,
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DWORD OpenDiagDriver ( char* port,
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Hard to say without the full C source. Are you building the DLL according to the CIN rules (see Using External Code in LabVIEW)? Mapping clusters to C code in DLLs is not a simply process and we generally recommend to create wrappers. However, since your structures are fairly straightforward, you could use the "Adapt to Type" as you are trying to do.
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http://detritus.blogs.com/lycangeek

PDA: How does the VI in the "Calling External Code (Inline C Method)" example link to the called functions?

The PDA module provides an example of calling external code via an inline C
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Donovan B wrote:
Hi Dan,
It looks like there is an OSVERSIONINFO struct and GetVersionEx function available in the coredll.lib for the application to call on a PDA running Windows Mobile 5.0. On both operating systems, it looks like the GetVersionEx function is defined in winbase.h, so I am not sure if there is some kind of linking between the two or if the header file is automatically included when building the executable or not. Let me do some more research and I'll let you know.
The information for the function on Windows Mobile can be found here.
Message Edited by Donovan B on 12-19-2007 06:33 PM
While the API functions are mostly the same for Windows Mobile and normal Windows the actual implementation and compilation is obviously not and there is no need for that. Windwos Mobile is typically (not sure if there are other versions at all) ARM based, while the desktop version is x86 based. A huge difference.
And when LabVIEW creates a PDA executable it mostly creates a bunch of hidden C files, invokes the Visual C for Windows CE
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Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Calling external C-functions in DLLs with struct as parameters

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