PXISA President’s intro: What is the PXI standard & why is it important?

Author : Bob Stasonis | President of the PXISA

02 May 2021

Bob Stasonis_PXISA President

What is a standard? Well, it depends on your perspective. Webster’s Dictionary defines a standard as “a level of quality or attainment” and “an idea or thing used as a measure, norm or model in comparative evaluations”. In the world of money, it can describe what value is behind the currency – for instance, American currency was once underpinned by the ‘Gold Standard’.

This viewpoint was originally featured as the intro to EPDT's 2021 PXI for T&M supplement, included in the May 2021 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.

But in the world of test & measurement, a standard defines a product’s form/factor and software rules, so that multiple instrument vendors can ‘play nicely’ together. As President of the PXI Systems Alliance (or PXISA), I work with our members to help define and support the PXI (PCI eXtensions for Instrumentation) standard, which the Alliance has supported since 1998.

As a Test Engineer, why is this important to you? Why should you care? Perhaps a little bit of history is in order. In the 1970s and 1980s, most automatic test systems (ATE) were manufactured by just a few vendors. You gave them a purchase order and they built your ATE. The test engineer was only responsible for designing the test fixture and writing test code.

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Entering the 1990s, a new modular instrumentation standard called VXI (VME eXtensions for Instrumentation) was on the horizon. Many supporters of this standard developed just one piece of an ATE. So, for example, one company specialised in chassis, another manufactured switching, another system controllers, and so on. All members of the VXI standard pledged that their products would be interoperable with other member’s products. This made it possible to bypass those huge, monolithic ATE system companies and build just what you needed, at  a more affordable cost. The advent of VXI also created new business niches to support DIY development. Cable manufacturers, connector designers, software developers and other businesses worked around the VXI standard.

Fast forward to today and PXI is now the dominant modular instrumentation standard for electronics testing. There are literally thousands of products that address new technologies such as 5G, autonomous vehicles and others. And the reason that PXI has grown so much and works so well is that over the last 20+ years, the standard has been managed and protected, and it is always evolving to meet present day needs – all through the efforts of the PXISA.

Without a non-profit organisation such as the PXISA to manage a standard, there is the possibility of the standard becoming obsolete. Or if one company manages a standard, it can become decidedly narrowly focused on that one company’s market niche. The PXISA has over 60 members who have pledged to work together and ensure that, collectively, the members give customers what they need for test.


Fortunately, our technical committee listens very closely to the test & measurement industry’s needs. If you go to www.pxisa.org and click on ‘Specifications’, you will see links to specifications ranging from the original PXI 1.0, back in August of 1997, as well as updates and new directions for PXI, ending up with PXI-6 (Express Software Specifications 1.4) and PXI-2 (Software specifications 2.6) in March of 2020. An important point to note is that backward compatibility is part of the charter of the technical committee. So where possible, a Gen 1 PXI module will work in a 2021 PXIe chassis that has hybrid slots, as well as working with the newest generation’s PXI products.

Education is another role that a standards organisation plays. The PXISA generates many newsletters (in multiple languages) annually that present articles about how PXI solved one or more problems for a particular application. The newsletters also highlight the latest products from our members. If you can’t find what you are looking for, you can contact the PXISA and we can steer you toward the right member or members.

PXI multi-vendor ecosystem

Finally, a standard with a long history provides peace of mind. Longevity denotes success, and specifications changes/updates assure users that the products are relevant to today’s testing needs. No one wants to hear the word obsolete!

We have a good mix of old and new participants on the PXISA Board of Directors and in its Technical and Marketing committees. I have personally held several roles with the PXISA since its inception. The Head of the Technical Committee has been directing the Committee almost since the beginning as well. I don’t want to say that the PXISA is a bunch of old guys, but it certainly does contain a blend of experience and new ideas. We recognise the history, but also that we need new people and ideas to move forward.

Well, I think that covers it. Long history, backward compatibility, evolving specifications and educating the test & measurement industry on what is available. By maintaining a high standard for the PXI standard, PXI will continue to be relevant far into the future…

EPDT May 2021 PXI for T&M supplement cover

Meanwhile, our annual EPDT PXI for T&M supplement (p21 digital issue) includes technical features: explaining how flexible, modular PXI test systems can automate fault insertion to improve automotive software quality (p24 digital issue or web version); reviewing why, to keep up with the demands of modern device test, a modular, integrated, software-defined test set-up is essential (p27 digital issue or web version); discussing how PXI-based dynamic digital instrumentation with PMU functionality allows test engineers to verify connections from the tester to the device-under-test and the structural integrity of the DUT (p29 digital issue or web version); and finally, we include a case study from nanoelectronics R&D hub, imec detailing how it used software-defined modular PXI instrumentation to build a highly parallel measurement system for in-fab semiconductor wafer test, helping streamline the R&D process flow (p31 digital issue or web version).

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