The latest trend in PXI is…boxes!

-May 13, 2014

VTI Instruments

One-box solutions are not limited to wireless testing applications.  I had the pleasure of interviewing Tom Sarfi, VP of Product Management for VTI Instruments.  VTI was recently acquired by Ametek, but retains its brand and charter.  A key segment in that charter is dynamic signal analysis (DSA), where noise, vibration, and harshness are characterized.  This has traditionally been performed by LAN-based data acquisition systems, with LAN delivering the communication backbone to remote data acquisition units.  VTI has added the EMX series to their portfolio.  While the CMX09 chassis has a LAN interface like the other data acquisition systems and boxes, it is actually a PXI Express chassis internally.

Jet engine test is a targeted application by VTI.  The large size of the engines demand a distributed acquisition system, using LAN as the backbone.  The EMX series supports PXI modules, but is commonly controlled over LAN.

Tom said that PXI allowed the company to sell PXI modules independently, or as bundled solutions.  Precision timing is distributed to the chassis over LAN using IEEE-1588 timing, and then locally to the modules over the PXI backplane.  PXI Express also gives the customer an alternative if total bandwidth exceeds gigabit LAN speeds- go directly to a controller using a PCI Express link.  One downside of PXI, Tom said, was the lack of ruggedized products for the harshest environments.  Here, VTI designed many of their own products to their exacting environmental specifications.

Marvin Test Solutions

Speaking of ruggedness, flightline testing of avionics and weapon systems pushes instrumentation to its very limits.  But this is exactly the world Marvin Test Solutions lives in, according to Mike Dewey, Marketing Manager for the company formerly known as Geotest.  If you are running out onto a runway to test the readiness of a Maverick missile on a fighter jet’s underwing, you really don’t have time to push a cart around and wire up test equipment.  Extremely rugged one-box testers are purpose-built for this application. And what are inside these hardened pieces of military equipment? You guessed it- PXI.

The PATS-70 tester is used for flightline test of “Warthog” A10/C upgraded avionics.  It is a ruggedized one-box tester based on PXI, and leveraged from Marvin’s MTS-207 system.  Variants of the MTS-207 are also used to test the Maverick and Hellfire missiles.

Marvin deploys a purpose-built 14-slot PXI card cage inside the MTS-207, based on 3U and 6U modules.  An internal heater keeps the modules humming at sub-zero temperatures, while the modules are carefully designed or selected to meet the +65C requirement at the high end.  Internal shock absorbers cushion the PXI modules, while conformal coating protects the modules against humidity and other harsh environments.  Mike said that Marvin chose PXI because the small size allowed it to be ruggedized, and the software and hardware modularity gave Marvin considerable flexibility.  Compact PCI, closely related to PXI, is also deployed.  The one drawback is that commercial PXI products are not traditionally designed to these environmental extremes, so depending on the product, significant engineering may be needed to select and modify a commercial product.

National Instruments

No modular survey is complete without a conversation with National Instruments.  I spoke with Luke Schrier, Senior Group Manager at NI.  Luke confirmed the same trend, but offered a few cautions.  If the customer is choosing the solution due to the perceived benefits of modularity, do they retain those benefits when integrated into a box solution? Sometimes yes, sometimes no, he observed.  This is particularly true if the customer wishes to add additional modules themselves or customize the solution.  Luke described NI’s strategy as a platform-based approach that makes alliance partners more productive when creating these new solutions.

The NI PXIe-1085, shown above, has a removable bezel seen as a blue-gray ring wrapping around the front of the chassis.  This is designed to be removed so system integrators and alliance partners can attach specialized fixturing or mounting hardware with good mechanical and EMC performance.

Luke gave one example of the NI PXIe-1085 chassis, where a removable bezel allows partners to create customized solutions with good mechanical and EMC integrity. RADX Technologies is an example of a partner using the chassis internally to create a box-like instrument.  Of course, NI’s LabView software plays a prominent role as well.

RADX Technologies

With that tip, I was able to speak with the CEO of RADX Technologies, Ross Q. Smith.  Indeed, the product page of the RADX website shows two versions of their one-box tester, the LibertyGT SDSI (Software Defined Synthetic Instrument).  The SDSI concept is that the instrumentation, when driven by RADX’s measurement science software, can be re-purposed to emulate measurements from a number of different instruments.  Depending on the options purchased, the SDSI can be reconfigured to be a spectrum analyzer, signal generator, digital oscilloscope, power meter, multimeter, digital I/O, or a BERT.  That is a lot of instrumentation in a small package!

                LibertyGT SDSI                                                      LibertyGT 1200B Benchtop SDSI
RADX Technologies offers two versions of their SDSI product. On the left is a one-box tester that is explicitly modular.  On the right is a benchtop equivalent with embedded display.  

Users may add modules or their own measurement science to either platform.  What makes the benchtop product so unique is that the entire front panel hinges down to expose the PXI modules.  The animation at the top of its product page here shows how the front panel folds down to allow a user to insert an additional module.  Ross told me that RADX has made the entire environment user upgradeable and customizable, from the hardware modules, to the measurement science, to the automation environment, to the test programs, and so forth. LabView is the basic software in the instrument, and LabView FPGA can be used to change the embedded FPGA algorithms.


This was a whirlwind tour of the “box from modules” phenomenon.  Each of the vendors offers more than what I reported, and many other vendors also offer similar products.  It is a clear trend, but why?  It’s all about how ecosystems interact.

Frequent readers know that I have been saying that the growing PXI ecosystem will produce unexpected results as it expands.  This is a great example- the wide variety of modules are influencing the design of boxes in some cases, blurring the distinction between modules and boxes.  

The moral of the story is this:  While thinking outside the box is considered a positive attribute, sometimes it is just as interesting to think inside the box!

See also:
•    Mods and Rockers.  Epic rivalry between modules and boxes
•    Does test equipment really need knobs and displays?
•    Increasing the speed of traditional box instruments

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