Ceyear 3986 Series, Руководство по программированию

Страница: 32 / 139

2 Remote Control
2.3 I/O library
24

Overview of I/O library
…………………………… …………………………………………………24

Installation and configuration of I/O library
……………………………………………………………
24
2.3.1 Overview of I/O library
As a library of software programs pre-written for the instrument, the I/O library is called an instrument
driver. It is considered as the intermediate layer of the software between the computer and the
instrument hardware equipment, composed of function library, utility program and tool kit, and used as a
software code module set that corresponds to a planned operation, e.g. configuring, reading from,
writing to or triggering the instrument. It resides in the computer as the bridge and link between the
computer and the instrument and provides a easily programmed high-level modular library so that the
user no longer needs to learn complex low-level programming protocols specific to an instrument. The
instrument driver is the key to rapid development and test of measurement applications.
From the aspect of function, a general instrument driver usually consists of a functional body, an
interactive developer interface, a program developer interface, a subprogram interface and an I/O
interface as shown in Fig. 2.12.
Application
Instrument drive program (functional body)
Interactive developer
interface
Program developer
interface
Subprogram interface I/O interface (VISA)
Figure 2.7 Instrument Driver Structure Model
The detailed description is given as follows:
1) Functional body. This is the main functional part of the instrument driver and can be understood as
the framework program of the instrument driver.
2) Interactive developer interface. For user's convenience, a graphical interactive developer interface
is generally provided in the application development environment that supports the development of
the instrument driver. For example, the function panel in Labwindows/CVI is an interactive
developer interface. In the function panel, each parameter of the instrument driver function is
represented by a graphical control.
3) Program developer interface. It is a software interface for recalling of the instrument driver function
by the application, such as the dynamic link library file .dll of the instrument driver of the Windows
system.
4) I/O interface. It is used to complete the actual communication between the instrument driver and the
instrument. Bus-specific I/O software (such as GPIB and RS-232) and also common standard I/O
software (VISA I/O) across multiple buses can be used.
5) Subroutine interface. It is a software interface for the instrument driver to access other support
libraries including database and FFT function. When the instrument driver needs to recall other
software modules, operating systems, program code libraries and analysis function libraries to
complete its task, the subprogram interface will be used.
2.3.2 Installation and configuration of I/O library
With the development of the test field application from the traditional instrument to the virtual instrument,
the instrument driver has experienced different development processes in order to solve the instrument