Load a complex dll in Labview

[adobefree@gmail.com]

Hi guys:

  I need to load a dll in labview, the prototype is :

long function(const char   a[],
     const double b,               
     const int    c,   
     double d[5][23],)  
     double e[4], 
     );

I set the prototype in labview is:

uint64_t Function(const CStr a,

const double b,

const int32_t c,

Array2DDouble **d,

double *e);

  but the function can't work ,  i guess there maybe some isuue at parameter d , the enclosed file is the config box , 

Anyone tell me where the problem is?

thanks

Message Edited by adobefree@gmail.com on 06-05-2010 10:46 PM

[srikrishnaNF]

Hi adobefree@gmail.com,

  labview supports only com dlls...Check before using this.

Thanks and regards,

srikrishnaNF

[adobefree@gmail.com]

yes , i have checked that , it is

[cschneider]

hi, 

you can just do a simple check: if you configured your interface node, right-click it and select "Create .c File"...then a header file is created and you can compare your data types in YOUR dll with the ones LabView expects...

Also, I don't really know if your char[] is compatible with a CStr..perhaps you can try using a numeric byte of U8 which you can create by typecasting a string to an U8-array (but this is only a guess)

good luck

christian 

[rolfk]

The problem is indeed your parameter d (among possibly other things such as the calling convention, etc).

LabVIEW array handles are a specific datatype only meant for LabVIEW or DLLs written to understand LabVIEW datatypes. Your 2D array is certainly not a LabVIEW array datatype but a simple Array Data Pointer. 

While you could represent a 2D array in C as an array of pointers to 1D arrays, this is not how it is done for matrix like arrays. Instead a 2D array in C is normally really just a 1D array with x * y number of elements.

So configure your d parameter to be a Array Data Pointer with 2 dimensions. And if this is an output parameter (a parameter that is filled in by the function) avoid the next LabVIEW Call Library Node (CLN) beginner problem and initilize the array to be of the right size before passing it to the CLN. While LabVIEW will take care about allocating and resizing arrays as needed inside VIs, it can under no circumstances know how much memory your C function would need and the C function can not allocate LabVIEW compatible memory in any way. So it is your responsibility as programmer to do that explicitedly before passing any array data pointer to a CLN.

Same applies of course for parameter e.

Also unless your DLL is 64 byte, the long type of the return value of the function never would translate to an int64 datatype (and for Windows 64Bit it is still 32bit, while for most any other 64bit OS it would be indeed 64bit).

Don't you love how Microsoft always tends to differ with the rest of the world?

Message Edited by rolfk on 06-07-2010 09:41 AM

[rolfk]

---

srikrishnaNF wrote:

Hi adobefree@gmail.com,

  labview supports only com dlls...Check before using this.

Thanks and regards,

srikrishnaNF

---

I'm sorry, but LabVIEW supports COM (OLE, ActiveX) DLLs through its ActiveX nodes, .Net assemblies through the .Net nodes and classical DLLs exporting functions through the Call Library Node. Not sure how this would qualify as "only".

Message Edited by rolfk on 06-07-2010 09:38 AM

[adobefree@gmail.com]

thanks for all of your suggestions , i will try it  , and update the status in time

[adobefree@gmail.com]

i have tried to config the prototype as upfloors:

and also malloc the right memory before pass into CLN

but still can't work , so i have to change the "d" in c dll definition from d[5][23] to d0[23],d1[23],d2[23]...... , it's ok ,

Is there any suggestion?I do really wana to know , how to pass c type n dimensions array in labview?

Message Edited by adobefree@gmail.com on 06-08-2010 08:48 PM

[rolfk]

This doesn't make sense to me. Maybe it is the C++ declaration (a constant array declaration as function parameter wasn't valid in standard C AFAIK) that means something else than I think it does but in standard C

d[5][23] creates an array of 5 * 23 elements (as function parameter it obviously doesn't create that array but make sure the C compiler complains if you pass it anything else).

Where I start to wonder is the difference in number of parameters you show in your (presumably dummy) C prototype and in the picture. And of course the two one dimensional arrays after your supposedly not working parameter that are used as output parameter but nowhere allocated in the diagram, or did you use the Array Size parameter in the CallLibrary Node configuration dialog to make sure the are always allocated to a minimum size?  Also a long really really isn't 64 Bit eventhough I'm not sure how that would crash.

[adobefree@gmail.com · Accepted solution]

Good news. I have fix it