Calling a dll made with LV6i

HI,
I use C++ builder and I want to call a dll which was made with LV6.
When I try to run the programm i get this error message:
Access violation at adress 30193AC6 in module 'LVRT.DLL'. Read of address
FFFFFFFF.
someone knows about it?

I'm using MS VC++ 6 and I have some similar problem with LV build DLLs using the example from the Developer zone.
The problem does no longer occure after I have updated to LV 6.0.2.
Maybe this will solve your problem too.
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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Can LabVIEW call a DLL built with VS(2005) C++ with /CLR and Without an Entry Point

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Attachments:
Test.vi ‏36 KB

Roberto N. wrote:
Thank you Jordan, I'm using Labview 7.1.
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Rolf Kalbermatter
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a division of Test & Measurement Solutions

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> Thanks for the information Greg. There is no documentation on this
> issue, except for the email that we got from NI Support. This is
> quite a new realm for us and NI alike. We would like to know what
> your experiences have been on this subject. If you have a bit of
> information, perhaps we should suggest a topic. As I said, this is a
> new frontier for LabVIEW, and there are a lot of things that NI
> doesn't know, and I'm sure a few of the programmers out there have
> figured out.
>
I often answer emails from home, but I work for NI on the LV development
team. So anything I know about, NI knows about. The info I was
describing about the DLL execution system is not well documented since
we were hoping that it would work we
ll with the way Windows Apps are
typically written. I suspect that we will need to write a Tech Note
to cover the nitty gritty. This sort of info gets lost in manuals,
and it is subject to change as we learn how people are expecting to
use it.
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In general, we believe that LV DLLs are thread savvy, reentrant
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Using a "fopen" call in a DLL made with MatLab for Labview

Dear Sirs:
My name is Juan Crespo and I write you from Spain. I answer if you could help me with a Labview problem. This is the problem.
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Thank you very much in advance and please sorry for my bad english
Best Regards
Juan Crespo
Attachments:
foo_wrapper.c ‏2 KB

Dear Juan Crespo,
normally I don't answer questions concerning Matlab because I have no experience with it. But your question was waiting a long time and had to do something with DLL I decided to look at it.
Your C code has a serious error. You are declaring a variabale named "in1" as "double *". You do not set this pointer to point to a variable. Then you use this uninitialized pointer in the fscanf function to read in from the file. The value is written somewhere in the address space at a place where "in1" is pointing randomly. This will cause an error or crash.
Declare "in1" as "double" like you have declared "out". You must change some other places where you have used "in1".
Waldemar writing from Germany
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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Hello all,
My program consist of:
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Hello Bas,
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Message Edited by darkxceed on 02-12-2010 04:33 AM
Message Edited by darkxceed on 02-12-2010 04:33 AM
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dhiraj03416 wrote:
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Message Edited by rolfk on 10-30-2009 01:32 PM
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#OSName: Microsoft Windows XP Service Pack 3
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N
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Attachments:
error.PNG ‏11 KB

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Hi,
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=========================
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Nils Gokemeijer wrote:
So,
we bought an optiphase interferometer, and it comes with a dll and with LabVIEW example code.
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They did provide a GetDllVersionchar(Cstr arg1, long arg2) which does work, (offcourse, it uses a standard C string pointer)
but GetDllVersion(Cstring arg1) does not work. (offcourse not, it using the Cstring class)
Is there a way to get CString classes to work in LabVIEW? (with a struct, or an binary array or whatever?)
Or do I have to write a wrapper dll to convert CString classes to standard C string pointers?
Thanks.
I'm afraid this won't really be
possible without a wrapper DLL. A CString is more like an object with
internal pointers and last time I checked into a DLL with a
disassembler it seemed that the actual layout of the internal structure
depends on the size of the string that is contained, with small strings
being entirely embedded and larger strings being a pointer to the
string. Trying to figure out these difficulties is something you should
leave to compiler developers and not try to do yourself.
One way that might be possible is to actually only create three or four
C functions that are exported by a helper DLL. These functions would
allocate a CString, copy a CStr into it and out of it and one to
deallocate it. As far as LabVIEW is concerned you would treat the
CString simply as a uInt32.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Calling a dll made with LV6i

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