The LAN eXtensions for Instrumentation (LXI) consortium was formed
in 2005, and the LXI standard has experienced widespread adoption
in just a short time. In June, the the LXI Consortium held its
general meeting in Beijing, China, where 187 product developers and
system integrators gathered to hear the latest developments and
attend a mini trade show.
To learn more about the promise LXI holds for automotive and
aerospace applications, I recently interviewed, Bob Rennard,
president of the LXI Consortium.
Q: Briefly review LXI's role within the context of test and
measurement technologies.
A: At its core, LXI is simply a common application of
standard, commercial Ethernet for test applications. It is a group
of leading test and measurement vendors agreeing upon a common
implementation to simplify product development and system
integration.
LXI is a better interconnect technology for test and measurement
than that offered by legacy GPIB-based systems. The LXI Consortium
selected Ethernet because it is stable. Test systems, particularly
those used in military and industrial automation applications,
often must last many years and Ethernet has proven remarkably
stable for almost four decades. Of course speeds and capabilities
keep improving, but the core connectivity and backward
compatibility has proven to be very reliable.
Q: How would you assess the state of LXI technology adoption today?
A: The adoption of LXI is the fastest of any new standard in the
test industry's history. To date there are more than 50
manufacturers that have joined the LXI Consortium and there are
more than 325 LXI-compliant products with more on the way. Some
members report LXI products represent more than half their
instrument shipments, and others report LXI versions of their
products overtaking non-LXI versions of the same instrument.
Migrating to LXI is as easy as attaching new cables and
readdressing a global address variable. The new system can also
integrate GPIB components where needed. The transition is seamless
and Ethernet discovery and network management tools make the system
setup easy with a low cost. As integrators become more familiar
with LXI, we are seeing very impressive results and innovative
applications.
Q: How does LXI uniquely support mil/aerospace and automotive
applications?
A: LXI offers integrators many new tools and capabilities
previously unavailable to the test and measurement industry. In
fact, the benefits of LXI prompted the US DoD to select LXI as the
preferred platform for the upcoming ECASS upgrade. Some advantages
of the technology include:
- Unlimited nodes and distance. Unlike other test I/O technologies, Ethernet and LXI are not
limited by distance or system size, and they support copper, fiber,
and wireless links. Integrators have used these features in test
ranges, where the device under test ( DUT) is not co-located with
the test suite. A military example may be a missile test range or
an antenna test range, where long distances are involved.
Automotive applications include test track applications where
wireless links or distributed nodes are required. Other high
channel count applications include aircraft and automotive strain-
gage tests, jet engine testing, and automotive engine or body
control module test.
- Mulitcast and peer-to-peer communication. In many test systems, the DUT or monitoring instruments may need
to trigger multiple events. A common example might be monitoring
current or voltage, where an alarm condition triggers a shut down
sequence to prevent damage to sensitive downstream equipment. With
traditional instrument I/O, the controller monitors the alarm
condition then sends an SRQ to initiate a shut-down sequence.
Unfortunately, the timing depends upon controller loading and is
not deterministic. With LXI, a digital multimeter ( DMM) or power
supply may detect an overvoltage condition and immediately send out
a multicast message to other instruments in the system, bypassing
the controller. Further, with a common notion of time provided by
IEEE 1588 in LXI Class B and Class A, the alarm trigger can execute
a well-coordinated shutdown sequence without ever involving the
controller.
- Low-cost, readily available infrastructure. Unlike some T&M interfaces that require specialized, expensive
cards and cables, LXI uses standard Ethernet cables and routers.
Integrators can purchase cables from their local electronics
retailer, and Ethernet adapters are standard on most every computer
produced today.
Q: Can LXI leverage GPIB, VXI, and PXI architectures?
A: Absolutely. LXI was developed with the knowledge that test
systems often last many years, customers have large inventories of
perfectly good legacy test equipment, and not all products are
available simultaneously on all formats. The result is hybrid
systems, and the LXI Consortium worked hard to ensure LXI works
well with other formats.
For example, the transition from GPIB to LXI can be as simple as
replacing GPIB cables with LAN cables and changing a global address
variable. LXI offers integrators many new tools and capabilities,
but integrators can adopt them when they are ready. The LXI
specification also defines bridges and adaptors to ensure legacy
equipment can be added to LXI systems. We already have GPIB-LAN
adaptors, PXI-LXI card cages, VXI-LXI Slot-0 controllers, and
M-Module bridges offered by several members.
Q: What are some challenges or roadblocks to LXI technology
adoption?
A: Like any other standard, the biggest challenge is balancing
supply with demand. This means simply getting a critical mass of
products and vendors to cover a wide variety of applications. With
over 325 products to date, including scopes, power meters, DMMs,
and RF gear, we are quickly approaching critical mass. The next
hurdle is getting software tools, application examples, and
integrator experience. LXI Class C offers a very easy transition to
LXI, requiring little in the way of new infrastructure or software.
While it replicates the point-to-point connectivity familiar to
existing I/O formats, it does not take advantage of the real
eye-opening benefits Ethernet can offer. As integrators become
familiar with application examples and software tools evolve to
take advantage of Ethernet's networking capabilities, LXI adoption
will accelerate well ahead of where we are today.
Q: The meeting in Beijing generated a record turnout; are there
special opportunities in China?
A: China represents a tremendous opportunity for LXI and the test
industry. First, much of the world's manufacturing is shifting to
China, creating new opportunities for both western and Chinese
companies. Second, there is a significant aerospace industry and
rapid growth in telecommunications, both historically large
consumers of test gear. Third, there are many engineers familiar
with commercial Ethernet and Chinese companies, and the Chinese
government supports the low-cost, open nature of Ethernet. We see a
lot of support from the Chinese government, in the form of the
China LXI User's Group, aerospace-defense contracts, and academic
research.
We believe China will quickly become a leading user and developer
of LXI products and systems. LXI is ideal for western companies
outsourcing to China. With the Web interface and Ethernet
connectivity, engineers in Europe or the US can monitor
manufacturing processes or collaborate with Chinese colleagues from
their home offices. They can see results and waveform displays,
instrument setups, and program steps in real time. They can also
control instruments remotely, if they have the proper security
clearance, as if they were sitting beside their colleagues in
China.
Q: Looking to the future, how will LXI technology evolve?
A: LXI will continue to follow the Ethernet community, adding
capabilities as they become available. In the short term, the LXI
Technical Committee has improved instrument discovery to make it
easier for integrators to plug instruments onto a test subnet and
have the system identify and self-configure addresses. Other
improvements include event logging to record event sequences,
simplifying system troubleshooting, and a common ID schema, making
system asset management easier.
The ID schema, added to the standard LXI Web page, makes it easy
for military, medical, and other documentation-centric industries
to automatically track instrument model, serial number, firmware
rev, last cal, next cal, and other relevant factors over the
network. The Technical Committee is also working on resource
management protocols to ensure instruments in multiple application
environments don't encounter problems when multiple applications
try to use the same instrument simultaneously.
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