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© National Instruments Corp. 3-1 NI-488.2 User Manual for Windows
Chapter 3
Developing Your Application
This chapter explains how to develop a GPIB application program using NI-488
functions and NI-488.2 routines.
Choosing How to Access the NI-488.2 DLL
Applications can access the NI-488.2 dynamic link library (gpib.dll) either by using
the NI-488.2 language interfaces for C or Visual Basic, or by directly accessing the
gpib.dll. The NI-488.2 language interface is the easiest and fastest method, and it is
adequate for most applications.
If you want to access the gpib.dll from languages other than C and Visual Basic, or if
you have special needs for accessing the gpib.dll, then you must use the direct entry
functions. These functions are identical to the NI-488 and NI-488.2 calls, except for the
following two differences:
• You must preface each function name by the characters DLL . For example, instead of
using the NI-488 function ibwrt, use the direct entry function DLLibwrt.
• The number of arguments taken by each function is increased by three. The last three
parameters are, in order, a pointer to the ibsta variable, a pointer to the iberr
variable, and a pointer to the ibcntl variable. Your application must declare its
own ibsta , iberr , and ibcntl variables to use the direct entry functions.
Choosing Between NI-488 Functions and NI-488.2 Routines
Your NI-488.2 software includes two distinct sets of subroutines to meet your application
needs. For most application programs, the NI-488 functions are sufficient. You should
use the NI-488.2 routines if you have a complex configuration with one or more interface
boards and multiple devices.
The following sections discuss some differences between NI-488 functions and NI-488.2
routines.