Can I compile DAQmx7.5 programs with DevC++?

[superfrenkie]

Hi,

we are beginning to acquire measurements with NI-USB6009 DAQ and we installed NIDAQmx7.5 libraries to exploit its advanced features. But when we compile with Dev C++ the example files we have  linker errors such as    " [Linker error] undefined reference to `DAQmxCreateTask@8' ", for every DAQmx function we call.
For the NIDAQmxBase these errors didn't occur. How can we solve this problem using Dev C++?

Thanks for your help,
Marco

[WM_John_Weeks]

Make sure you are linking with NIDAQmx.lib. You will find it in

Program Files\National Instruments\DAQmx ANSI C Dev\lib\msvc\

[superfrenkie]

Yes I compile with NIDAQmx.lib, and import libraries and include files. I think the problem is with the Dev C++ compiler itself.

Message Edited by superfrenkie on 08-30-2005 11:58 AM

[WM_John_Weeks]

Oh. I'm using VC++.net with success. I'm building a DLL using standard C++. Are you using anything special like managed code? (I'm quickly getting out of my depth here)

The "@8" on the end looks like a mangled name of some sort. You may need to do something to turn off the mangling.

[AlessioD]

Hi,

the true point of the issue is that DevC++ is probably not completely supported. This is basically why you are getting linking errors to 'DAQmxCreateTask@8' and others probably. The final @8 reports the size of the parameters the function is expecting or something similar.

Anyways, I suggest you take a look at JoeSavage's approach on this web page .

He basically posted a Wrapper DAQmx C code that can be included in your C code and resolve the names the linker is missing.

AlessioD

[superfrenkie]

I tried to compile NIDAQmx.c inside my project as the post's author suggests but the compiler returns this error '' invalid conversion from `void*' to `int32 (*)(const char*, TaskHandle*)'  '' for this line of code '' if (!(DAQmxLoadTask_Ptr = (void*) GetProcAddress(DLLHandle, "DAQmxLoadTask")))  ''. This is repeated for a lot of similar instances and I don't know how to fix it. Perhaps the whole procedure is incorrect, should I compile NIDAQmx.c in another directory?

Thanks a lot, Marco.

[superfrenkie]

Hi,

we tried to overcome the problem using the Visual C++ command line compiler. The compiling and linking are ok (for example we tried with the ContAcq-IntClk.cpp file  from NI) but  if we run the program we have the following error

DAQmx Error: Device identifier is invalid.
Device Specified: Dev1

Task Name: _unnamedTask<0>

Status Code: -200220
End of program, press Enter key to quit

What could be the cause in your opinion? OurDAQ is the USB6009. Thanks a lot,
Marco
 

[AlessioD]

the USB-6008 device needs to be recognized by NI_DAQ 7.5 under MAX. You need to follow the indications reported on this KnwoledgeBase  in order for the Device to be assigned a correct identifier. AlessioD

[superfrenkie]

Great!

thanks for your suggest, everything seems to work fine, the problem was to switch the device between NIDAQmxBase and NIDAQmx. Now we can choose to work with DevC++ or command-line VisualC++...

Marco.

[WM_John_Weeks]

If you're compiling this as C++, you can't automatically convert a void * to other types. I'm not sure about function pointers and C; I thought with standard C this would be OK. You will have to cast the return value of GetProcAddress to the actual function pointer type, like this:

typedef int32 (* LoadTaskFuncP)(const char*, TaskHandle*);
DAQmxLoadTask_Ptr = (LoadTaskFuncP)(GetProcAddress...

or, using more modern C++

DAQmxLoadTask_Ptr = reinterpret_cast(GetProcAddress...

The typedef is just to make it more readable. I haven't compiled this, so take warning...