readme.txt

广泛用于示波器上的gpig工业标准接口的计算机编成库

Win32 Microsoft Visual Basic Language Interface for Windows 95
Version 1.0.
Copyright 1996 National Instruments Corporation.
All Rights Reserved.


The VISUAL BASIC subdirectory contains the following:

   README.TXT    -  This information file

   VBIB-32.BAS   -  Visual Basic source file with NI-488.2 routine
                    and NI-488 function prototypes

   NIGLOBAL.BAS  -  Visual Basic global module containing certain
                    predefined constant declarations

   SAMP4882.MAK  -  Visual Basic NI-488.2 sample project file        

   SAMP4882.FRM  -  Visual Basic NI-488.2 sample form file       

   DEVSAMP.MAK   -  Visual Basic device-level sample project file
       
   DEVSAMP.FRM   -  Visual Basic device-level sample form file      


Creating Your Application Program
---------------------------------

You must include VBIB-32.BAS and NIGLOBAL.BAS in your Microsoft Visual
Basic (version 4.0 or higher) application project file. VBIB-32.BAS 
contains the NI-488.2 routine and NI-488 function prototypes for 
interfacing with the dynamic link libray GPIB-32.DLL. NIGLOBAL.BAS 
contains GPIB-specific variable declarations and constant definitions.


Regarding I/O Functions and Data Types
--------------------------------------

The I/O functions (for example, ilrd, ilwrt, etc.) can be used to 
transfer all data types (byte, word, long) provided the count parameter 
specifies the number of bytes to transfer. For example, if you want to 
transfer an array of 16 longs, the correct transfer count to specify is 
16*4=64.


Note on Asynchronous I/O Calls
------------------------------

The asynchronous I/O calls (ibcmda, ilcmda, ibrda, ilrda, ibwrta, ilwrta)
are converted to synchronous I/O calls in the Win32 Visual Basic language
interface. With Visual Basic version 4.0, the buffers that are passed to 
DLLs are remapped. When the call to the DLL returns, the remapped buffer
is freed up. As a result of this, the buffer passed to GPIB-32.DLL for
asynchronous I/O operation becomes invalid when the asynchronous I/O call
returns. This makes it impossible to safely use the asynchronous I/O
functions. Therefore, they were remapped to their synchronous 
counterparts by the Microsoft Visual Basic 4.0 language interface.