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Chapter 2 113
Programming Fundamentals
C Programming Using VTL
C Programming Using VTL
The programming examples that are provided are written using the C
programming language and the HP/Agilent VTL (VISA transition
library). This section includes some basic information about
programming in the C language. Refer to your C programming
language documentation for more details. (This information is taken
from the manual “VISA Transition Library”, part number
E2090-90026.) The following topics are included:
“Typical Example Program Contents” on page 113.
“Linking to VTL Libraries” on page 114.
“Compiling and Linking a VTL Program” on page 114.
“Example Program” on page 116.
“Including the VISA Declarations File” on page 117.
“Opening a Session” on page 117.
“Device Sessions” on page 118.
“Addressing a Session” on page 119.
“Closing a Session” on page 121.
Typical Example Program Contents
The following is a summary of the VTL function calls used in the
example programs.
visa.h This file is included at the beginning of the file to
provide the function prototypes and constants defined
by VTL.
ViSession The ViSession is a VTL data type. Each object that
will establish a communication channel must be
defined as ViSession.
viOpenDefaultRM You must first open a session with the default
resource manager with the viOpenDefaultRM
function. This function will initialize the default
resource manager and return a pointer to that resource
manager session.
viOpen This function establishes a communication channel
with the device specified. A session identifier that can
be used with other VTL functions is returned. This call
must be made for each device you will be using.