National Instruments GPIB-PC - Manual (Page 62)

©National Instruments Corp. 4-1 GPIB-PC User Manual
Section Four - GPIB-PC
Functions — Overview
This section consists of Section Four and a BASIC supplement. Section
Four contains a discussion of the important characteristics common to
all programming languages. The BASIC supplement lists the GPIB
functions for BASICA and QuickBASIC languages.
When you order a language other than BASIC, you receive a separate
supplement unless your language is very similar to BASICA. Insert any
new supplements in place of or in addition to Section Four A.
General Programming Information
The following characteristics are common to all programming
languages:
• A Status Word,
• Error Codes,
• A Count Variable,
• Read and Write Termination,
• Device Function Calls, and
• Automatic Serial Polling.
A thorough understanding of the concepts presented here is essential to
the implementation of a GPIB system.
The next several paragraphs explain the status word ( IBSTA ), the error
variable ( IBERR ), and the count variable ( IBCNT ). These variables are
updated with each function call to reflect the status of the most recently
referenced device or board.