LabVIEW
C++ module in labview
There have been several suggestions but they all are not likely to work without some extra wrapper DLL code or similar thing.
Alex Chee wrote:I have an issue here. I need to have C++ (or other low level language) to interface specially made equipments. A C++ developer is doing that. But I also need to have Labview control a group RF equipments. Over the years, we have built a big number programs. I would like to have these two different program together. I perfer to use Labview to call C++ module.I looked Labview 8.5 and it seems possible to do that. An example is great.Thanks,Alex
Let's look at the different solutions:
1) .Net: You likely will need to wrap your unmanaged C++ library into some managed .Net component to be calleble through LabVIEWs .Net interface.
2) ActiveX: The same as above. C++ can be used to create ActiveX components but is not the same. So you likely will have to create an ActiveX interface for your C++ library.
3) Call Library Node: This node can only call standard C exported functions (or globally defined C++ functions aside from the name mangling that occures. C++ libraries however are mostly written as a collection of objects with methods and possibly public data members. The Call Library Node can't directly interface to that. You would have to tell your C++ programmer to provide standard C exported wrapper functions for all the object methods you need and also the constructor and destructor for all opjects.
A little example kept simple for this purpose:
#include <iostream> using namespace std; class CRectangle { int x, y; public: void set_values (int,int); int area () {return (x*y);} } * PRectangle; void CRectangle::set_values (int a, int b) { x = a; y = b; }:
For this your college would have to add this extra stuff to his library (in theory! my C++ is not that great and this likely contains some syntax errors):
extern "C" {PRectangle CRectangle_cnstructor(void);
void CRectangle_destructor(PRectangle o);
void CRectangle_set_values(PRectangle o, int a, int b);
int CRectangle_area(void);
}
PRectangle CRectangle_cnstructor(void) {return new CRectangle;
}
void _set_values(PRectangle o, int a, int b) {
o->set_values(a, b);
}
int CRectangle_area(PRectangle o) {return o->area();}
void CRectangle_destructor(PRectangle o) {delete o;
}
This is really just some code put together quickly to give you an idea about how to go about this and should not be taken as the ultimate guide how to wrap C++ code to be callable from standard C or in this case the LabVIEW Call Library Node.
Rolf Kalbermatter
