how to do with a pointer element in a structrure when I call a dll in labview

[tingerfei]

struct ZT_USBBOARD
{
long lIndex;
HANDLE hHandle;
short nCh;
long lData;
long* plData;
long lCode;
};


FUNCTION：long APIENTRY OpenUSB7kC (ZT_USBBOARD* bs)
---open the device USB7310
the valid input parameter:1Index


There,how to do with 'HANDLE hHandle' and 'long* plData 'in a cluster of labview? DO you understand?
WAITING....Thinks!

[tst]

Structs can be handled by using Adapt to Type, just build the cluster and wire it in. Pointers can be handled as intergers and passed on.
Did you read Using External Code in LabVIEW? If not, go to Help>>Search the LabVIEW bookshelf.
You can find some more DLL related material here.

[tingerfei]

Thanks! I read the articles and examples that you said before.but I haven't found the answer.I know I should use the cluster,but in the cluster,how to do with 'handle'?

[tst]

If I remember correctly what I have read about this, you can't use the handles themselves in LV, but can only pass them on to other DLL functions. I know that for windows API DLLs this works fine - you define the handle as a U32 and just pass it on to the next function.
I'm not 100% positive that this is so, but as far as I can remember that's what I read.

[tst]

Just to clarify, I believe that you can get the values the pointers are pointing to if you use Adapt to Type and Handles by Value, but I don't know if you can use the pointers themselves for anything.

[tingerfei]

Thank you very much!
The problem has been solved.The reason can be the choice of 'stdcall' and 'c'!But a new problem appeared.The program is normal when it runs first,but it is abnormal when it runs again and labview is closed.what can I do?

[tst]

Well, I'm not entirely sure what your function does, but if it opens a connection to a hardware resource (USB?), you should probably close that connection before trying to open it again, using whatever function was supplied. It may be corrupting your memory.
Also, make sure you're using the proper representations for your types, because this can also cause some overwriting.