National Instruments NI-488.2 - Manual (Page 54)

Chapter 4 Developing Your NI-488.2 Application
© National Instruments Corporation 4-17 NI-488.2 User Manual
In your Win32 application, you need to load gpib-32.dll before
accessing the gpib-32.dll exports. The following code fragment shows
you how to call the LoadLibrary function to load gpib-32.dll and
check for an error:
HINSTANCE Gpib32Lib = NULL;
Gpib32Lib=LoadLibrary("GPIB-32.DLL");
if (Gpib32Lib == NULL) {
return FALSE;
}
For the prototypes for each function, refer to the NI-488.2 Help.
For instructions on accessing the online help, refer to the
Using the
NI-488.2 Documentation section in About This Manual .
For functions that return an integer value, like ibdev or ibwrt , the pointer
to the function needs to be cast as follows:
int (_stdcall *Pname)
where *Pname is the name of the pointer to the function. For functions that
do not return a value, like FindLstn or SendList , the pointer to the
function needs to be cast as follows:
void (_stdcall *Pname)
where *Pname is the name of the pointer to the function. They are followed
by the function’s list of parameters as described in the NI-488.2 Help. For
instructions on accessing the online help, refer to the
Using the NI-488.2
Documentation section in About This Manual .
Following is an example of how to cast the function pointer and how the
parameter list is set up for
ibdev and ibonl functions:
int (_stdcall *Pibdev)(int ud, int pad, int sad, int tmo,
int eot, int eos);
int (_stdcall *Pibonl)(int ud, int v);
Next, your Win32 application needs to use GetProcAddress to get the
addresses of the global status variables and functions your application needs.
The following code fragment shows you how to get the addresses of the
pointers to the status variables and any functions your application needs:
/* Pointers to NI-488.2 global status variables */
int *Pibsta;
int *Piberr;