Extproc: DLL function requires struct pointer, howto ?

Hi there !
Does anybody know if and how it's possible to pass
a struct pointer like
typedef struct _NETRESOURCE {
DWORD dwScope;
DWORD dwType;
DWORD dwDisplayType;
DWORD dwUsage;
LPTSTR lpLocalName;
LPTSTR lpRemoteName;
LPTSTR lpComment;
LPTSTR lpProvider;
} NETRESOURCE;
to an external DLL function ? Currently i've created
a wrapper DLL which accepts ordinary datatypes and fills
the struct properly. But i would like to have a more
'generic' way to use DLLs.
Any Ideas ??? Thanks in advance !

Hi!
I am also in need of the solution to this, but could not get it right yet!
Would you perhaps share your current solution (writing the wrapper) with me?....
I will keep you posted if I find a way of using ora_ffi with a C Struct
Bye!

Similar Messages

Interface dll function with struct in LabVIEW

Hello,
I have a function:
HPDF_SetInfoDateAttr (HPDF_Doc pdf, HPDF_InfoType type, HPDF_Date value)
The problem is in the last input, HPDF_Date value. HPDF_Date is a struct which looks as followed:
typedef struct _HPDF_Date {
HPDF_INT year;
HPDF_INT month;
HPDF_INT day;
HPDF_INT hour;
HPDF_INT minutes;
HPDF_INT seconds;
char ind;
HPDF_INT off_hour;
HPDF_INT off_minutes;
} HPDF_Date;
Now I created the following cluster in LabVIEW:
In the Call Library VI I set the type to "Adapt to type" and tried the dataformats. However none of them worked. Can any one explain to me why the cluster is not accepted by the function? I know the error is there because the error function of the dll says that I input an invalid datetime format.
The datetime format may look like this:
Member
Effective values
year
month
Between 1 and 12.
day
Between 1 and 28, 29, 30, or 31. (Depends on the month.)
hour
0 to 23
minutes
0 to 59
seconds
0 to 59
ind
Relationship of local time to Universal Time (" ", +, −, or Z).
off_hour
If "ind" is not space, 0 to 23 is valid. Otherwise, ignored.
off_minutes
If "ind" is not space, 0 to 59 is valid. Otherwise, ignored.
Solved!
Go to Solution.

Actually LabVIEW can. A struct passed by value is simply pushed element for element onto the stack. So instead of defining a structure to pass as a single parameter to the CLN, you configure the CLN to take one parameter per structure element (and use the right datatype of course).
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

EXTPROC DLL function "unsigned long" (DWORD) problem.

Hi all!
I'd like to pass a value to a function inside a DLL. The DLL parameter is a DWORD,
I've specified the LIBRARY parameter as UB4 and the FUNCTION parameter is BINARY_INTEGER.
This works pretty well until the value is larger than 2147483647 . This is (of course) beyond
the limit of BINARY_INTEGER and PLS_INTEGER.
BUT --- ext proc only can be mapped like this
BINARY_INTEGER
BOOLEAN
PLS_INTEGER
------------>
[UNSIGNED] CHAR
[UNSIGNED] SHORT
[UNSIGNED] INT
[UNSIGNED] LONG
SB1, SB2, SB4
UB1, UB2, UB4
SIZE_T
So .. how can I pass a "real" unsinged integer to an external
function, which allows a range up to 2^32-1 == 4294967295 ??
Any hints? Thanks in advance!!
No, I do not want to create a wrapper DLL :-)

Hi!
I am also in need of the solution to this, but could not get it right yet!
Would you perhaps share your current solution (writing the wrapper) with me?....
I will keep you posted if I find a way of using ora_ffi with a C Struct
Bye!

How to pass a struct to a DLL function and accessing it in another VI

Hi friends,
                   I am new to labview. I need to create a demo program in labview ,for displaying image from our own image capturing system. We have a DLL ( build in VC++) containing functions for capturing image from our system. Now I need to create a VI library for some of functions in DLL and Create a Demo program using those created subvi library . I used "Call Function node" and created some of subvi's.
Some of our DLL functions need to pass struct pointers. Our function prototype will be similar to the following function.
__declspec(dllexport) int __stdcall Initialize( unsigned char *imagebuffer,struct config *Configuration);
The passed struct is similar to
struct config
double                val1[3];
unsigned short   val2;
bool                    val3;
bool                    val4[3];
unsigned char    val5;
unsigned char   val6[3];
bool                    val7[26];
For passing "unsigned char *imagebuffer" I initialized array with "Numeric constant " and set the size of the array and send to the function.
The problem here is, I used this array in one of the subvi.
How can I use the returned imagebuffer array in my main demo program. How to connect the image array to subvi "Connecter Pane"
And which control can I use to display the image. The image data I get is form of 1-D Array .
The second problem is,
   For passing the structure, I used "Bundle " and filled the bundle with all the datatypes as in my struct and passed to the function. Is it correct ? How to access this bundle after returned from function in another Vi. ie.) How to connect this bundle to the connter pane ?
Thanks for your valuable suggestions.
aajjf.
Message Edited by aajjf on 04-19-2007 05:34 AM

aajjf wrote:
Hi friends,
                   I am new to labview. I need to create a demo program in labview ,for displaying image from our own image capturing system. We have a DLL ( build in VC++) containing functions for capturing image from our system. Now I need to create a VI library for some of functions in DLL and Create a Demo program using those created subvi library . I used "Call Function node" and created some of subvi's.
Some of our DLL functions need to pass struct pointers. Our function prototype will be similar to the following function.
__declspec(dllexport) int __stdcall Initialize( unsigned char *imagebuffer,struct config *Configuration);
The passed struct is similar to
struct config
double                val1[3];
unsigned short   val2;
bool                    val3;
bool                    val4[3];
unsigned char    val5;
unsigned char   val6[3];
bool                    val7[26];
For passing "unsigned char *imagebuffer" I initialized array with "Numeric constant " and set the size of the array and send to the function.
The problem here is, I used this array in one of the subvi.
How can I use the returned imagebuffer array in my main demo program. How to connect the image array to subvi "Connecter Pane"
And which control can I use to display the image. The image data I get is form of 1-D Array .
The second problem is,
   For passing the structure, I used "Bundle " and filled the bundle with all the datatypes as in my struct and passed to the function. Is it correct ? How to access this bundle after returned from function in another Vi. ie.) How to connect this bundle to the connter pane ?
Thanks for your valuable suggestions.
aajjf.
Message Edited by aajjf on 04-19-2007 05:34 AM
You say nothing about how your cluster looks but I'm afraid you did the standard error here and placed arrays in it. That is not what the C structure is representing for several reasons.
First fixed size arrays in C are inlined inside a structure, so are not a pointer but for the case of your val1 element three doubles.
Second although not relevant here because of above point: LabVIEW arrays are not the same as C arrays. LabVIEW uses a pointer to a pointer and has the size of the array in elements prepended to the array data. C simply uses a pointer and all the rest is the programmers sorrow. The Call Library Node does convert the top level element of variables you pass according to the type configuration of that parameter but does no conversion of internal elements at all. So passing clusters with anything like arrays or strings is always wrong unless the DLL is aware of the specific datatypes LabVIEW uses.
Last but not least you can end up with alignment issues. Elements in structures are aligned by every C compiler to a certain value. This value can be defined by the programmer in the project settings or for Visual C through #pragma pack() statements in the C code. The alignment rule says that an variable is aligned to the smaller of the two values that are either a multiple of the variable element size or the alignment setting. Most 32bit code nowadays uses 8 bit default alignment but LabVIEW always uses 1 byte. In your case there is nothing to observe since the large variables are at the beginning. Otherwise you might have had to insert filler elements in the LabVIEW cluster.
One last thing bool is a C++ type only. Its size is 1 byte and incidentially this is the same LabVIEW uses for Booleans.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

FRM-40734 when calling a foreign function requiring more than 1 dll

I have been experiencing difficulties in calling external DLL functions from SECURSIGN.DLL. This time no peculiar type of parameter is involved, just four varchar2.
A dump file "ifrun60_dump_nnn" is generated by FORMS every time I issue the aborted call to the foreign function.
Inside the form dump file, apart from useless info like Registers and so on, the message: "Could not find Module32First"
I know for sure that SECURSIGN.DLL needs also other DLLs, and that the first foreign function I call, calls other functions in other DLLs. I found that Module32First is a routine within each of the following DLLs:
Cl32
d2kwut32
d2kwut60
I copied all those DLLs in the current work directory along with my FMB/FMX, in ORANT\BIN, in C:\WINNT\SYSTEM.
I modified the PROCEDURE LoadLibrary (part of the FFI-generated PLL code) to load those DLLs along with SECURSIGN.DLL: no problem in loading all the DLLs that I wish, but the error persists.
How can I avoid all that mess and the FRM-40734 error?? Is there a specific problem in resolving the references to other DLLs?
Please notice that - on the same computer - in Visual Basic everything (and the very same call in particular) works perfectly.

I have noticed just now that a dump file having a name like ifrun60_dump_299, is generated by FORMS every time I issue the aborted call to the foreign function.
Inside the form dump file, apart from useless info like Registers and so on, the message:
"Could not find Module32First"
By a FILE/FIND/CONTAINING TEXT I searched all the DLLs, and I noticed that Module32First is a routine that can be found within each of the following DLLs:
Cl32
d2kwut32
d2kwut60
I tried to load those DLLs along with SECURSIGN.DLL by modifying the PROCEDURE LoadLibrary into the FFI-generated PLL code, and I have apparently no problem in loading all the DLLs that I wish, but the error persists, and that dump file is constantly generated, always looking for the "Module32First" routine.
How can I avoid all that mess and the FRM-40734 error??

LabVIEW call Win32 API DLL function from third party

Hi everyone,
I'm trying to build a LabVIEW 2010 interface on 32-bit Window XP system to configurate and communicate to an Anglient laser head through its USB expansion box. I contacted the vendor and they shared a win32 API with some dll files. I started with a function called "A55292Find", but the CLF node always pop up error 1097.I checked the MSDN to get the corresponding LabVIEW data type for CLF.
My question is: Do I need to initialize those arguments? (How can I know the values of them if initialization is needed?)
Could anyone help me figure out what's the problem?
Here is what I have from API documents about this function:
The A55292Find function returns lists of handles and board types for all the 55292 USB
Expansion Modules connected to the system.
A55292RC __cdecl A55292Find(
HANDLE hBoxes[], // List of handles for the boxes found. (as Unsigned 32-bit integer numeric)
BOARDTYPE PortABrdType[], // List of board types for slot A boards (as Unsigned 16-bit integer numeric)
BOARDTYPE PortBBrdType[], // List of board types for slot B boards (as Unsigned 16-bit integer numeric)
WORD *spMaxBoxes); // dimension for all of the passed arrays. (as Unsigned 16-bit integer array data pointer)
// (function return type as Unsigned 32-bit integer numeric)
Parameters
HBoxes[] Array that will receive the list of HANDLES for all the 55292 boxes connected.
PortABrdType[] An array that will receive Slot ‘A’ board type information for each 55292 box.
PortBBrdType[] An array that will receive Slot ‘B’ board type information for each 55292 box.
spMxBoxes Passes the maximum number of values that can be held in hBoxes, PortABrdType, and PortBBoardType arrays to the A55292Find routine and returns the actual number of boxes found
The return value will be one of the following A55292RC return codes:
Value Meaning
A55292_NO_ERROR No error
A55292_TIMEOUT Timeout accessing a shared memory
Remarks
This routine must be called to obtain handles and board type information used in calling all the other routines. If there are significantly more array elements than boxes, the routine will take longer to complete.
These are the definitions:
typedef DWORD A55292RC; enum{A55292_NO_ERROR, A55292_HANDLE_ERROR,...}
typeder WORD BOARDTYPE; enum{A55292_PCAL_BOARD, A55292_NO_BOARD, ...}
Thanks a lot,
Kang
Solved!
Go to Solution.
Attachments:
call A55292Find.vi ‏10 KB

nkang11 wrote:
Hi Mr. Kalbermatter,
As you told me, I should try to use the defined enumeration words as control and indicator.
For the previous CLF node, it successfully returned the hardware configuration (I have only connected a board at slot A):
But I really want to see a string return as "A55292_PCAL_BOARD" which is defined by "typedef WORD BOARDTYPE; enumeration {...}; Does that mean I need to change the data type or do something like "converter"? Or initialize the array first, then convert it to string type?
Right now, I'm trying to open the laser card by using "A55292PcalOpen(HANDLE hDev, SLOTSELECT SlotSelector);" function which requires to use the enumeration constants from " typedef WORD SLOTSELECT; enum {A55292_PORT_A, A55292_PORT_B};" but I'm confused to shot an constant control to a new CLF node.
Since almost all of the arguments in dll function are typedefined as WORD, short and struct et al, I hope you could give me some hints on it.
Thank you very much sincerely!
Kang
Depending on the actual C implementation you can simply create a LabVIEW enum with the according item names or use a ring control instead. Teh enum requires the numeric values of the items to be in consecutive order without any gaps in between. This is a given if the C definition never assigns a specific number to the item. If the C enum is not consecutive you need to go with a ring control instead.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Thrid party DLL function call.

Hello,
I am a programming novice trying to learn more about Java. I am currently working on a project for my employer (a side project really) that is used in generating some specific alpha-numeric codes. Actually, I am re-writing an existing program into Java as a personal exercise for myself but it may have some useful applications down the line.
This project requires me to use a 3rd party DLL function call. I have been trying to follow through the process of using the JNI interface, however, I believe that I need to create a wrapper DLL to handle the function call. Does anyone know how to do this or can they point me in the right direction? I believe the 3rd party DLL was written in C++ but that's all I know at this point.
Any help is appreciated.
TIA

To those of you who will look this topic up and wonder how I was able to do that here:
(using Visual C++ for the example)
3rd party DLL : Key32.dll
wrapper DLL: Key32Liaise.dll
SWIG interface: Key32Liaise.i
wrapper class: Key32Liaise
1) Make reference to your external function call as if it were a class method. The class name should be that of your "wrapper" class. (e.g. Key32Liaise.getHashCode() ) I like to call the wrapper class the "laise" class because it acts as the go-between.
2) Download SWIG. Create your interface file and run the command: swig -java -shadow -c++ Key32Liaise.i This will generate Key32Liaise.java shadow class and Key32Liaise_wrap.cxx wrapper code.
3) Compile the Java code into Class files and generate a header file for the wrapper class (i.e. javah Key32Liaise). You will need this header file even though the SWIG site doesn't mention this.
4) Open VC++ and open a new project file Key32Liaise to create a DLL. Write the C++ code that calls up the function from the Key32.dll file. You will have to look that up from the MSDN site...too much to put down here.
5) Include the appropriate files and complile the wrapper DLL.
Hope that make sense!!!

Question on the parameter type of DLL functions

Question on the parameter type of DLL functions
I am trying to develop an interface to control a laser with LV8.2 I am planing to use the VI “Call Library Function Node” to call the DLL and set the exact same parameters of functions in the DLL.
According to the DLL manual of the laser, there are six functions. One of the prototypes is: function getstatuspointer : pointer. I don't know how to set this parameter for the function. Is there anyone who can give some hints? Thanks!
BTW :The following is a description of the function:
This function returns a 32 bit pointer to the STATUS data structure (Tstatusrec). In the 32 bit DLL, every application is using its own copy of the data structure (local
memory). The data structure is a packed structure. "packed" means that the fields in the structure are not aligned on word or double-word boundaries.
Tstatusrec = packed record
                        size : word;
                        initstat : byte;
                        queuefill : byte;
                        anzapp16 : word; (not used)
                        anzapp32 : word;
                        anzdock16 : word; (not used)
                        anzdock32 : word;
                        dll16ver : tchararray; (not used)
                        dll32ver : tchararray;
                        excimerver : tchararray;
                        excimer : TExcimerStatus;
                  end;

Hi Jack,
This is a good starting point when using Call Library Function node. Check out this Help Page
Van L
NI Applications Engineer

I just recently upgraded to the new itunes and getting this, ADAdPolicyEngine_DidEnterStation, could not be located in the dynamic link library C:|programsFiles(x86|itunes.dll, itunes.exe Entry point not found itunes Error 7 windows 127

I just recently upgraded to the new itunes and getting this, ADAdPolicyEngine_DidEnterStation, could not be located in the dynamic link library C:|programsFiles(x86|itunes.dll, itunes.exe Entry point not found itunes Error 7 windows errors127

See iTunes launch errors caused by iAdCore.dll.
Review the rest of the user tip if required.
tt2

Receive a cluster from a dll function

Hi,
I have a function in a DLL which returns a C struct. I want to know how can I receive a cluster from a CLFN?
struct info:
struct typedata{
int a;
int b;
const char * c;
int d;
int e;
}data;
function call:
const typedata * hostinfo(int param);
Solved!
Go to Solution.

LVCoder wrote:
Thanks a lot both of you for letting me know about my dumb assumption that 2 different processes can use the same memory space.
Anyways, I figured out the problem with my code that was reading the double value.
the DLL function returns the address of the struct which has 5 elements.
struct test {
int a;
int b;
int c;
double d;
double e;
suppose the address I receive is 10
address of test->a = 10
address of test->b = 14
address of test->c = 18
address of test->d = 26 // I was refering it as address 22. but I forgot that I was on a 64 bit machine and that the OS will allocate the whole memory address for a double and won't utilize the 4 bytes left in the previous memory address.
thanks!
That has nothing to do with the bitness of your CPU or the OS. It is only dependent on the compiler alignment setting when you compile your DLL. Microsoft Compilers use a default alignment of 8 bytes. That means every variable or element inside a cluster will be aligned to the smaller one of either its own size or the default alignment.
You can change the compiler alignment either with a compiler switch or an explicit #pragma iin your source code where you declare the variables or structure typedefs.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

FRM-40734 when calling external DLL Function from Forms 6

Even though some answers were given to my previous help request ("Again: Forms 6 and user-defined data types") I wasn't able to solve the problem of passing a parameter of an user-defined type to an external DLL function residing in the SECURSIGN.DLL library (the closest solution was to declare that "composite" parameter using the ROWTYPE clause referencing a custom-made table created just for the sake of defining that perticular datatype).
So I concentrated on SECURSIGN.DLL functions using more trivial data types, like a function requiring just four character strings as parameters.
I generated the necessary PL/SQL support using the FFI.
I discovered that also the simplest calls to external functions fail at runtime with the generic error FRM-40734.
I located the error: it happens just at the moment of calling the function from within the FFI-generated package body. Before that, the DLL is loaded with no problem, the function is correctly registered, and a function handle is regularly returned.
As long as I can regularly issue the very same call with the very same parameters from Visual Basic, I can't understand what's going wrong (ALL the needed DLL are in the same directory as the FMB/FMX forms).
I will greatly appreciate any help that You may be able to provide.

I have noticed just now that a dump file having a name like ifrun60_dump_299, is generated by FORMS every time I issue the aborted call to the foreign function.
Inside the form dump file, apart from useless info like Registers and so on, the message:
"Could not find Module32First"
By a FILE/FIND/CONTAINING TEXT I searched all the DLLs, and I noticed that Module32First is a routine that can be found within each of the following DLLs:
Cl32
d2kwut32
d2kwut60
I tried to load those DLLs along with SECURSIGN.DLL by modifying the PROCEDURE LoadLibrary into the FFI-generated PLL code, and I have apparently no problem in loading all the DLLs that I wish, but the error persists, and that dump file is constantly generated, always looking for the "Module32First" routine.
How can I avoid all that mess and the FRM-40734 error??

Please send me Functional requirement specification's in bw regarding

Dear Experts,
Please send me any sample functional requirement specifications regarding MODELING,REPORTING,EXTRACTION.
points will be added
thanks very much
Regards,
SridharMenda
[email protected]

Hi,
check these links...
http://hosteddocs.ittoolbox.com/CM021805.pdf
a forum discussion on specs..
bex sample project/specs
assign points if useful ***
Thanks,
Raj

Type librarys for DLL functions that TestStand understands for parameter information

Using the C/C++ DLL call adapter I would like to specify a call to a DLL function and have TestStand (3) understand the parameter information.
Usually it says 'there is no parameter information available'. Today however I tried building a DLL in Visual C++ instead of CVI and got a bit further. TestStand recognized that there WAS parameter type information but then said 'The type library for this DLL does not contain enough information to determine whether this function parameter is a pointer to a single item, or an array of items."
So in a nutshell, does anyone know what options (in CVI or MSVC) I need to build with so that TestStand recognizes the function prototypes exported in the DLL? After all it's alot of work to type in all that parameter information.
Many thanks,
Ronnie
TestStand 4.2.1, LabVIEW 2009, LabWindows/CVI 2009

In CVI, you can get the parameter information into a DLL. First of all, you have to have a function panel (.fp) file with all of your exported functions defined as function panels. From this function panel file you can also generate a windows help file to document your DLL. Once you have the .fp file and .hlp file, you can enable references to them in the build target settings (Build->Target Settings...). Select "Type Library..." and check "Add type library resource to DLL" and "include links to help file" then browse to your .fp file. If there are descepencies between the functions defined in your .fp file and the actual functions you have exported in the DLL, then you may get a compiler error.
--Peter

Why does the DLL function executed by call library node fail when the Vi is re-opened?

Development System
OS: Windows XP
LabVIEW: version 10.0
DLL: Custom
Compiler: Visual C++ 6.0
Function Prototype: __declspec(dllexport) const char * test(void)
We have developed a DLL for use. The DLL compiles cleanly.  The DLL includes a function test.  The test function validates the functional capabilities of the DLL. I have followed the examples online, and I have used the import shared library tool in LabVIEW. The VIs created use the call library node.
When I create a VI calling the test function from the custom DLL using the call library node the VI executes the DLL function test flawlessly. I close the VI. When I re-open the VI and run it, I get an error code from the DLL.  However, if I go to the block diagram and set the path for the DLL in the configure call library node again then the VI executes the DLL function test flawlessly again.
I have to set the path for the DLL in the configure call library node every time I open the VI. The examples I downloaded from the community do not require this. What might the DLL be missing? What am I missing?
Solved!
Go to Solution.

I think it was rather unfair of me to ask for help with my DLL issue without disclosing more detailed information. As a corrective action, I have attached a zipped file. The zipped file contains the entire VC++ 6.0 project for compiling the DLL, the DLL, and the VI I have been using to test it.
###NOTE####
As a prerequisite to compilation and usage of the DLL you'll need to have installed Python 26 on your system.
You may obtain the MSI for correct version of Python from the following location:
http://www.python.org/ftp/python/2.6.6/python-2.6.6.msi
###NOTE###
Thank you very kindly for any assistance offered!
Thanks,
Bill
Attachments:
C_DLL_PYTHON_AND_LABVIEW2010.zip ‏1685 KB

Execute dll function using Java Technology

Can I use Java to execute an existing dll function? Currently this dll function is sits in Unix and was compiled using Borland C compiler. How can this to be done?

If you know all the entry ponts to the dll, and their parameters, return values and caling conventions then you should be able to write 'c' funtion prototype for them like this
stdcall int somefunc(int x, char *x);
If so, you can load the dll (on windows) with LoadModule
get each functions address with GetProcAddress
and cast the result to a pointer to the appropriate prototype
THEN you can write a JNI wrapper dll that makes these functions available from JAVA

Extproc: DLL function requires struct pointer, howto ?

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