How to Make a Win32 GPIB Application Using Direct Entry

You can directly access the gpib-32.dll from any programming environment that allows you to request addresses of variables and functions that a DLL exports. The gpib-32.dll exports pointers to each of the global variables and all of the NI-488 and NI-488.2 calls.

• int *user_ibsta;
• int *user_iberr;
• int *user_ibcnt;
• long *user_ibcntl;

At the beginning of your application, make sure that the following lines are included:

• On-line help
• View Documentation option on the CD-ROM
• Printed manual included with the GPIB Interface

There are a few functions that the 32-bit GPIB DLL exports with slightly different names. Here is a list of those functions:

• ibbna
• ibfind
• ibrdf
• ibwrtf

To access any of these four functions in your application, you must use the correct function name when calling GetProcAddress. For Windows 98/95 applications, use the 8-bit ASCII versions named ibbnaA, ibfindA, ibrdfA, and ibwrtfA. For Unicode applications, use the 16-bit wide versions named ibbnaW, ibfindW, ibrdfW, and ibwrtfW.

The prototypes for each function can be found in the Function Reference Manual. For functions that return an integer value, like ibdev, the pointer to the function needs to be cast as:

int (__stdcall *Pname)

where *Pname is the name of the pointer to the function. For functions (i.e., the 488.2 calls) that do not return a value, the pointer to the function needs to be cast as:

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 Function Reference Manual. Below 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);

Gpib32Lib = LoadLibrary("gpib-32.dll");

if (!Gpib32Lib) return FALSE;

if ((Pibsta == NULL) || (Piberr == NULL) || (Pibcntl == NULL) || (Pibdev == NULL) || (Pibonl == NULL)) { FreeLibrary(Gpib32Lib); Gpib32Lib = NULL; return FALSE; } else return TRUE; 

dvm = (*Pibdev) (0, 1, 0, T10s, 1, 0); if (*Pibsta & ERR) Then printf("Call failed"); (*Pibonl) (dvm, 0);