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1Instrument Control The Future of GPIB, VXI, and PXI
Welcome to our seminar on instrument control, where we will
discuss the state of instrument control technology and the future
of some of the most common and popular buses for controlling
instruments: GPIB, VXI, and PXI.
National Instruments Corporation Instrument Control The Future
of GPIB, VXI and PXI
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2Seminar Agenda
Evolution of instrument control GPIB bus
History Technical overview Software architecture
Other instrument control buses Stand-alone buses: Serial,
Ethernet, USB, and IEEE 1394 Modular buses: PCI, VXI, and PXI
Application development environments
In the seminar we will present the following topics:1. A brief
overview of the evolution of instrument control technology.2. The
overview leads into a more detailed tutorial on the GPIB bus. In
this section, we discuss
the history of GPIB, present a technical overview of the bus,
and discuss the software architecture that makes it a robust and
easy bus to use for instrument control.
3. We then discuss other instrument control buses.
Fundamentally, this discussion splits into two groups of buses:
Stand-alone buses similar to GPIB which include Serial (or RS-232),
Ethernet, USB, and
IEEE 1394 (or FireWire) Modular buses which include the PCI bus,
the VXI bus, and the PXI bus
4. Finally, we discuss application development environments
(ADEs) offered by National Instruments that integrate seamlessly
with our instrument control products and make your application
development task even easier.
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3Evolution of Instrument Control Hardware
GPIB
PC DAQ
PXI
VXI
ENET/USB
1975
1988
1997
1987
1995
Prior to 1975, developing automated test systems required
significant effort because of a lack of established standards for
interfacing to stand-alone instrumentation.GPIB, or IEEE 488,
provided a common software and hardware framework for connecting
instruments to computers, and significantly decreased the
development effort required to create an automated test system.
More than 25 years later, GPIB is still the most popular way to
automate stand-alone instruments.VXI, introduced in 1987, provided
the first industry-standard modular hardware for the test industry.
Because VXI targeted mainly high-cost applications, we introduced
plug-in instrumentation in 1988 to address the large number of
users that required a test system tightly integrated with a
standard PC at a low cost.In the mid-1990s, the industry began
considering standard computer buses such as Ethernet and USB as
possible alternatives for instrument control. Although these buses
offered some advantages, they have yet to gain widespread
acceptance in the industry.Because of its high cost and lack of an
integrated software and driver framework, VXI never achieved broad
market acceptance. To overcome these challenges and to provide an
ideal platform between PC-based plug-ins and VXI, PXI was
introduced in 1997. PXI leveraged the driver model of PC systems to
provide a high level of productivity to test system designers.
Today, PXI is the fastest growing instrumentation platform since
the introduction of GPIB.
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4VisionPXI Distributed I/O PLCsGPIB/Serial and VXI
Modular Instrumentation
System Management SoftwareTest Management, Data Management
Data Acquisition and Signal
Conditioning
Measurement and Control Services
LabVIEW MeasurementStudioOther
Software
Motion
LabWindowsTM/CVITM
Integrated Software Framework
The challenges that system developers face today lead to the
need for an integrated software framework. This framework must
decrease the complexities of integrating multiple measurement
devices into a single system by providing standard interfaces to
all I/O devices. Additionally, the framework must also provide
development tools to rapidly configure, build, deploy, maintain,
and modify high-performance, low-cost measurement and control
solutions. This integrated softwareframework must provide seamless
connectivity to the ever-evolving enterprise management systems on
which an organization standardizes. It is through this framework
that an organization delivers products to market faster, achieves
greater product quality, and lowers development and production
costs.An integrated measurement and automation software framework
delivers a modular, yet integrated structure for building
high-performance, automated measurement and control systems. For
maximum performance, ease of development, and system-level
coordination, the components of the framework must remain
independent, yet tightly integrated. This structure empowers
developers to rapidly build measurement systems and easily modify
them as the system requirements change. A key benefit of this
integrated software framework is that organizations become more
competitive because they can design and test higher quality
products and deliver them to market faster and more cost
effectively than ever before.
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5User Test Application Program
Instrument Drivers
Measurement Hardware
Conf
igur
atio
n an
d De
bugg
ing
Tool
s
Driver Engines and APIs
Instrument Control Buses
Platform for Instrument Control
Although this integrated software platform provides a vehicle to
incorporate devices ranging from instrument control, data
acquisition, and motion control to image acquisition, distributed
I/O and control of PLCs, in this seminar we focus on the platform
for instrument control applications.The diagram above shows the
interaction among the different layers in the architecture. The
bottommost layer, the hardware layer, is composed of measurement
hardware connected to a computer via an instrument control bus.
This hardware is controlled from the PC directly through a device
driver engine and application programming interface (API) or
indirectly through an instrument driver. Both of these layers
interact with configuration and debugging tools that help users
develop their instrument control application. Finally, these
software layers combine in the users test application program,
which could be a simple application or a complex test management
system.The remainder of this seminar examines the different pieces
of this platform as they relate to instrument control. We will use
the diagram above throughout the seminar to help you visualize
those pieces.
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6Instrument Control Buses
Measurement Hardware
Instrument Control Buses
We begin by discussing the hardware layer, specifically the
instrument control buses.
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7Types of Instrument Control Buses
Stand-Alone
GPIB
Serial
Ethernet
USB
IEEE 1394
Modular
PCI
VXI
PXI
We can separate instrument control buses into two fundamental
groups: You can use stand-alone buses to communicate with rack and
stack instruments. The most
common example of a stand-alone bus is GPIB. Other examples
include Serial (RS-232), Ethernet, USB, and IEEE 1394.
Modular buses incorporate the interface bus into the instrument
itself. Examples of modular buses are PCI, VXI and PXI.
We first discuss the GPIB bus and provide a historical
background, technical overview, and software architecture
overview.
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8Origins of GPIB
Originally designed by Hewlett-Packard in 1965 Interface for HP
controllers & instruments
National Instruments formed in 1976 Offered interfaces to
industry standard computers
DEC, IBM, etc. Offered alternatives to HP Basic
LabVIEW, LabWindows
The General Purpose Interface Bus (GPIB) was originally
developed by Hewlett-Packard (where it was called the HP-IB or
Hewlett-Packard Interface Bus) in the late 1960s to connect and
control their programmable instruments through their controllers.
With the introduction of digital controllers and programmable test
equipment, the need arose for a standard, high-speed interface for
communication between instruments and controllers regardless of
vendor. The GPIB soon became the clear choice.The first product
from National Instruments was a GPIB interface. Throughout its
history, NI has offered GPIB interfaces to industry standard
computers such as DEC and IBM computers. In addition, NI also
offered programming alternatives to HP Basic, the prevailing
standard in the early years of GPIB. These programming alternatives
included LabVIEW and LabWindows.
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9GPIB Standardization History IEEE 488.1 1975
Standardized the physical, electrical, and mechanical features
of GPIB IEEE 488.2 1987
Standardized software for controllers to interface with
instruments Standard Commands for Programmable Instrumentation
(SCPI) 1990 HS488 (Undergoing IEEE standardization)
High-speed GPIB (8 MB/s)
1965 1987 1990 19921975
HP de
signs
HP-IB
HP-IB
becom
es
IEEE 4
88 IEEE 4
88.2
Adop
ted, IE
EE 48
8
becom
es IEE
E 488.
1
SCPI
introd
uced
IEEE 4
88.2 r
evised
HS488
in app
roval
proces
s
2003
In 1975, the IEEE Standard Digital Interface for Programmable
Instrumentation (ANSI/IEEE Standard 488-1975 ) was released. IEEE
488 contained the electrical, mechanical, and functional
specifications of an interfacing system.Because the original IEEE
488 document did not contain guidelines for preferred syntax and
format conventions, the supplemental standard IEEE 488.2, Codes,
Formats, Protocols, and Common Commands was released for use with
IEEE 488 (renamed IEEE 488.1). IEEE 488.2 builds on IEEE 488.1 by
defining a minimum set of device interface capabilities, a common
set of data codes and formats, a device message protocol, a generic
set of commonly needed device commands, and a new status reporting
model.In 1990, the IEEE 488.2 specification added the Standard
Commands for Programmable Instrumentation (SCPI) document. SCPI
defines specific commands that each instrument class must obey.
Thus, SCPI attempts to guarantee complete system compatibility and
configurability among these instruments. You no longer need to
learn a different command set for each instrument in an
SCPI-compliant system, and you can easily replace an instrument
from one vendor with an instrument from another. The drawback is
that not many instruments are SCPI compliant.National Instruments
has proposed a high-speed extension of the IEEE 488.1 standard that
defines a handshaking method that increases the bus performance by
almost 10x. This standard is currently undergoing IEEE
standardization.
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GPIB Longevity
Extremely large install base: 510 million GPIB instruments An
agreed upon standard that has survived 30 years Robust and
reliable
Handshaking, shielded connectors, error handling, etc. Faster
than other buses for most of its life
Relatively fast at 1.5 MB/s (IEEE 488.1) Very competitive at 8
MB/s (HS488)
Easy for users to use and for vendors to implement
The GPIB bus is still extremely popular today, almost 30 years
after its creation. There are many reasons for this longevity, the
most important of which may be the extremely large installed base
of GPIB instruments (510 million instruments in use). It is an
agreed upon industry standard that unifies the method for
controlling instruments from multiple vendors.The GPIB bus is also
robust and reliable. Its defined handshaking mechanism, shielded
and rugged industrialized connectors, and error handling mechanisms
all ensure data integrity. The GPIB bus has been faster than other
buses for most of its life. It is still relatively fast at the 1.5
Mbytes/s transfer rate defined by IEEE 488.1 and is very
competitive at the 8 Mbytes/s transfer rate proposed by
HS488.Finally, the longevity of GPIB can be attributed to its
simplicity. You can easily learn to use the bus, and vendors can
easily implement instruments based on it.
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GPIB Technical Overview
Hardware specifications Software specifications
Now that we have seen a GPIB instrument control application,
lets look at a technical overview of the GPIB bus. We first discuss
the bus hardware specifications and then we present the software
architecture of a National Instruments GPIB system.
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GPIB Electrical Specifications Defined by IEEE 488.1 24 Lines
Cable specifications
Max cable length between devices = 4 m (2 m average)
Max total cable length = 20 m Max number of devices =
15 (min 2/3 powered on) Bus speed
1.5 MB/s with IEEE 488.1 8 MB/s with HS488
DIO5DIO6DIO7DIO8RENGND (TW PAR W/DAV)GND (TW PAIR W/NRFD)GND (TW
PAIR W/NDAC)GND (TW PAIR W/IFC)GND (TW PAIR W/SRQ)GND (TW PAIR
W/ATN)SIGNAL GROUND
DIO1DIO2DIO3DIO4EOI
DAVNRFDNDAC
IFCSRQATN
SHIELD
1
12
13
24
GPIB is a digital, 24-conductor parallel bus. It consists of
eight data lines (DIO 1-8), five bus management lines (EOI, IFC,
SRQ, ATN, REN), three handshake lines (DAV, NRFD, NDAC), and eight
ground lines. The GPIB uses an eight-bit parallel, byte-serial,
asynchronous data transfer scheme. This means that whole bytes are
sequentially handshaked across the bus at a speed that the slowest
participant in the transfer determines. Because the unit of data on
the GPIB is a byte (eight bits), the messages transferred are
frequently encoded as ASCII character strings.Additional electrical
specifications allow data to be transferred across the GPIB at the
maximum rate of 1.5 MB/sec because the GPIB is a transmission line
system. These specifications are: A maximum separation of 4 m
between any two devices and an average separation of
2 m over the entire bus A maximum cable length of 20 m A maximum
of 15 devices connected to each bus, including the system
controller with at least
two-thirds of the devices powered onIf you exceed any of these
limits, you can use additional hardware to extend the bus cable
lengths or expand the number of devices allowed.Note: For more
information about GPIB, visit the National Instruments GPIB Web
site at ni.com/gpib.
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GPIB System Configurations
Linear ConfigurationStar Configuration
A GPIB hardware setup consists of two or more GPIB devices
(instruments and/or interface boards) with a GPIB cable connecting
them. The cable assembly that connects devices consists of a
shielded 24-conductor cable with a plug and a receptacle
(male/female) connector at each end. With this design, you can link
devices in a linear configuration, a star configuration, or a
combination of the two.In the star configuration, multiple devices
are all connected from one device. The dual-sided connector makes
this type of connection possible. In the linear configuration, the
devices are daisy-chained with cables going from one device to the
next. Neither of the two configurations offers inherent advantages
over the other. Your specific needs determine how you connect your
instruments.
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Overcoming GPIB Specification Limits
Hybrid systems Use GPIB bridges: for example, GPIB-ENET/100
(GPIB to
Ethernet converter) for distributed instrument control Use
instruments with other native bus connectivity options
GPIB bus devices GPIB bus expanders connect more than 14
instruments GPIB bus extenders extend GPIB system cable lengths
As mentioned earlier, you can overcome the GPIB system
limitations and maintain the performance of your GPIB system. One
way to overcome these limitations is to use GPIB bridges. These
bridges offer a mechanism to translate between GPIB communication
and Ethernet communication for example. Using this, you can
distribute your measurement application over much longer
distances.You also can use GPIB bus devices such as expanders and
extenders. With expanders, you can connect up to double the number
of instruments (28) to a GPIB system and using extenders you can
overcome the cable length limitation. With fiber optic extenders,
you can extend the total cable distance in your GPIB system to more
than 1 km.
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HS488 Technical Details IEEE 488.1
Uses DAV, NRFD, and NDAC command lines for handshaking
Extra delays introduced by talker and listener monitoring two
extra lines
HS488 Uses only DAV line for handshaking Listener only monitors
DAV line, talker
asserts it when data is available
The IEEE 488.1 standard originally defined a three-wire
handshaking mechanism. This was done because many devices on the
system could not communicate fast enough over the bus, and this was
a method to ensure extra redundancy and that the data was received.
The talker and the listener used the three handshaking lines:
DAVData Valid NRFDNot Ready for Data NDACNot Data AcceptedEach
device would monitor two lines and assert the third when it was
ready to send or receive data.With the HS488 handshaking scheme, it
is assumed that modern devices can parse and send data quickly
enough so that both devices can monitor one line, the DAV or data
valid line, and send and receive data based on the electrical state
of that line. To ensure backward compatibility, HS488 devices use a
standard initial communication pattern over this line to determine
whether the other device is also an HS488 capable device. If it is
not, they revert back to the standard IEEE 488.1 handshaking
scheme.
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GPIB Instrument Control Software
Instrument DriversCo
nfig
urat
ion
and
Debu
ggin
g To
ols
Driver Engines and APIs
GPIB (NI-488.2)Configuration and debugging toolsVISA and
instrument drivers
We now discuss GPIB instrument control software. This discussion
is broken down into three sections: The NI-488.2 driver software
and API GPIB configuration and debugging tools Instrument drivers
and the VISA I/O library
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GPIB Communication
Similar to a well run classroom GPIB card
(controller-in-charge)
Teacher Instruments (talker/listener)
Students Service Requests (SRQ)
Students raising hands Messages (communication)
Talking between student and teacher Talking between student and
student (rare)
Before we discuss GPIB software, we first explore how GPIB
communication occurs. You can think of GPIB communication as
similar to a well run classroom. The GPIB card, also known as the
controller-in-charge, is equivalent to the teacher. The GPIB card
controls the bus communication and instructs devices on the bus
when to send and receive messages.Instruments on the GPIB bus are
the equivalent of the students in the classroom. They need the
permission of the controller to send and receive messages.
Instruments on the bus generally are referred to as
talker/listeners. The instruments request service using the SRQ
line on the GPIB bus, which is similar to students raising their
hands.Finally, messages on the GPIB bus are how communication
occurs on the bus. Messages are generally sent between the
controller and instruments (students and teachers) and very rarely
between the instruments themselves (student to student).
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GPIB Communication
Message-Based System Easy to conceptualize Different boxes
different languages
SCPI: attempt at industry standardization (
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Multiplatform NI-488.2 Software Compatibility
Windows2000/NT/XP/Me/9x/3.1
DOS
SolarisDigital UNIX
HP-UXMac OS
Mac OS X
PCs
LabVIEW Real-Time
Embedded
MacintoshWorkstations
The cornerstone of the National Instruments GPIB strategy is to
provide software compatibility unmatched in the industry today. We
support multiple platforms and have maintained the same software
API for more than a decade, protecting our customers software
development investment.National Instruments continues to leverage
new operating system technology to provide solutions when our
customers expect them. We currently offer our NI-488.2 driver
software solutions for all Windows operating systems, Mac OS, Sun
Solaris, and embedded applications through the LabVIEW Real-Time
environment.
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VISA
Virtual Instrument Software Architecture (VISA) Standard for
more than 10 years Created by VXIplug&play Systems Alliance
Controls GPIB, VXI, PXI, serial, and Ethernet
instruments with the same API USB to be added to standard
In the early 1990s, different commercial implementations of I/O
software existed not only for GPIB but also for VXI and serial
interfaces. These I/O software products were neither standardized
nor interoperable.As a step toward industry-wide software
compatibility, the VXIplug&play Systems Alliance was founded in
1993, with one of its goals to define one specification for I/O
software, Virtual Instrument Software Architecture (VISA).The VISA
specification defines a next-generation I/O software standard that
has been expanded for use with GPIB, VXI, PXI, serial, and Ethernet
interfaces. For example, after identifying which type of
instrumentation platform to use, the function VISA Write would work
for either a GPIB, serial, Ethernet, PXI, or VXI device. In
addition to these interfaces, VISA is currently being updated to
support communication with USB interfaces.
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Sample VISA Programs
viOpenDefaultRM (&rsrc);viOpen (rsrc, GPIB::1::INSTR, 0, 0,
&io);viWrite (io, *IDN?\n, 6, &count);viRead (io, buf,
1024, &count);viClose (rsrc);
LabVIEW
LabWindows/CVI
There are two sample VISA programs shown above. Both examples
use NI-VISA, the National Instruments implementation of the VISA
standard. The first shows a graphical representation of a VISA
communication in the National Instruments LabVIEW graphical
development environment. LabVIEW will be discussed in more detail
later in the seminar. The VISA Write block writes the data buffer
specified to the instrument indicated by the VISA session or
resource name. Then, the VISA Read function reads back 100 bytes
from the instrument.The second example uses NI-VISA in National
Instruments LabWindows/CVI, a development environment built on the
ANSI C programming language. We will discuss LabWindows/CVI later.
The program has the same functionality but includes session
management functions handled automatically in LabVIEW such as VISA
Open and VISA Close.Notice that both examples include a VISA
session resource descriptor. This descriptor specifies the type of
device that is being used for the communication. This example
refers to a GPIB instrument at address 1 with the descriptor
GPIB::1::INSTR. If the descriptor were changed to
TCPIP::10.10.10.10::myinst::INSTR, the same programs could have
been used with an instrument connected via an Ethernet
interface.
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Instrument Drivers
Set of software routines to control a programmable
instrument
Simplify instrument control Reduce user development time
Eliminates need to learn new programming protocol
Common architecture and interface
Application Development
Environment (ADE)
Instrument
Instrument Commands(*idn?, meas?)
Bus Communication Protocol(configure, read, write, trigger)
InstrumentDriver
Although VISA simplifies instrument control programming
significantly, it still requires low-level knowledge of instrument
communication and of instrument command sets. As an improvement,
instrument and software vendors began writing instrument drivers.
Instrument drivers are a set of high-level software routines to
control a programmable instrument. For example, instead of sending
four commands to an oscilloscope to set it up to perform an
acquisition, an instrument driver would have one function call that
configures the scope.Instrument drivers simplify instrument control
and significantly reduce the amount of time required to develop an
instrument control application. Not only do instrument drivers
eliminate the need for the user to learn new command sets for each
instrument, but they also provide a common architecture and
interface to the user.
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Instrument Drivers
Intuitive high-level functions Instrument addressing Command
string building Range checking Memory storage Data scaling Response
string parsing
Easy to use
Instrument drivers generally contain high-level functions that
not only perform configuration and measurement functionality, but
also handle details such as instrument addressing, command string
building, range checking, memory storage, data scaling, and
response string parsing.Instrument drivers are very easy to use
since they generally provide you with native functions for
whichever development environment you are using. You use instrument
drivers just like you would any other library in your programs.
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Instrument Drivers: Benefits
Drivers simplify test development Replace instrument command
programming High-level API isolates the instrument I/O Focus on
ease-of-programming
Drivers decrease learning curve Different instruments, common
structure
Instrument drivers simplify test development by replacing the
need for low-level instrument command programming and providing a
high-level API that isolates you from the I/O. This lets you
concentrate on developing the rest of your application, thereby
making your programming task easier.Because instrument drivers
provide a common and consistent structure, they decrease the
learning curve when going from one instrument to the next.
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History and Evolution of Instrument Drivers IEEE 488.2
Defines commands for identification, self test, and so on
No standard commands beyond these
SCPI Groups instrument functionality in
attribute groups Defines language for setting and
retrieving attributes Focused on message-based
instruments
1987
IEEE 4
88.2
1990
SCPI
LV & CVI Plug&Play Instrument Drivers
Standards for instrument drivers have evolved over the years,
with each standard building on the previous one. While all of these
standards have evolved, National Instruments LabVIEW and
LabWindows/CVI plug & play drivers have provided consistent
instrument control for more than 15 years.IEEE 488.2Created in
1987, this standard defines a set of commands for instruments to
perform such common tasks as identification, self test and so on.
The standard also defines the method for communication across the
bus but does not define any commands for performing measurement
tasks.SCPICreated in 1990, the Standard Commands for Programmable
Instrumentation or SCPI was the first standard to group instruments
into different classes and group instrument functionality into
attribute groups. The standard defines the language for setting and
retrieving instrument attributes and the commands for performing
common instrument tasks. SCPI is focused on message-based
instrument communication.
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History and Evolution of Instrument Drivers VXIplug&play
Focused on vendor interoperability A few standard functions
Source code Users requested interchangeability
Driver standard was needed to: Build on VXIplug&play driver
model Incorporate advanced features like
interchangeability, simulation, and state-caching
Provide high quality drivers
1987 1990 1993
IEEE 4
88.2
SCPI
VXIplu
g&play
System
s
Allianc
e
1998
IVI Fou
ndation
LV & CVI Plug&Play Instrument Drivers
VXIplug&playDefined to focus on multi-vendor
interoperability and defines a set of common and standard functions
that all instruments had to support. It also specifies that drivers
be provided in source code so that users could modify them.A driver
standard was still needed, though, that provided for instrument
interchangeability and other advanced functionality such as
simulation and state-caching. The IVI Foundation defines such a
standard.
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IVI: Interchangeable Virtual Instruments
IVI Foundation is an open consortium of Users: Boeing, Northrop
Grumman Integrators: BAE Systems Vendors: National Instruments,
Agilent, Tektronix
Founded in August 1998, incorporated in March 2001 27 member
companies Recently absorbed SCPI Consortium and
VXIplug&play Systems Alliance
Such a standard was defined by the Interchangeable Virtual
Instruments (IVI) Foundation. The IVI Foundation is comprised of
user companies such as Boeing and Northrop Grumman, integrators
such as BAE Systems, and instrument and software vendors such as
National Instruments, Agilent Technologies, and Tektronix.The IVI
Foundation was founded in 1998 and incorporated in March of 2001 as
a Delaware non-profit organization. It has an active membership of
27 companies, and it recently absorbed the SCPI Consortium and the
VXIplug&play Systems Alliance unifying all standards for
instrument control software under one roof.
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IVI Foundation: Goals
Hardware interchangeability Maximize software reuse Preserve
test software investment
Deliver consistent driver quality Software interoperability
Architecture to integrate software from multiple vendors
Standard access to driver capabilities
The goals of the IVI Foundation are as follows:Hardware
interchangeabilityAllow users to exchange instruments in their
system with little or no software modifications, thereby maximizing
software reuse and decreasing cost by preserving your investment in
test software.Driver qualityDefine specifications for drivers that
provide more consistent quality and robustness and provide the user
with familiarity with the instrument driver standard.Software
interoperabilityDefine an architecture to easily integrate software
from multiple vendors and provide a consistent and standard method
for access to driver capabilities.
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IVI Architecture
IVI Instrument Specific Layer and DriversIVI Instrument Specific
Layer and Drivers
IVI Generic Class Layer and DriversIVI Generic Class Layer and
Drivers
User Test Application Program
Conf
igur
atio
n an
d De
bugg
ing
Tool
sDriver Engines and APIs
The IVI architecture splits into two layers: an instrument
specific layer, which provides driver quality and consistency, and
a class layer, which achieves instrument interchangeability.
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Instrument Driver Network
ni.com/idnet LabVIEW plug & play,
LabWindows/CVI plug & play, and IVI
More than 2,200 instrument models from 150 vendors for LabVIEW,
LabWindows/CVI and Measurement Studio
The instrument driver network (IDNet) at ni.com/idnet is your
source for the most comprehensive collection of instrument drivers
available anywhere. IDNet has LabVIEW and LabWindows/CVI plug &
play drivers, as well as IVI drivers, to use with both of those
environments as well as Measurement Studio for Visual Basic, Visual
C++ and Visual Studio .NET.The instrument driver network offers
instrument drivers for more than 2,200 instrument models from
upwards of 150 vendors.
National Instruments Corporation Instrument Control The Future
of GPIB, VXI and PXI