Ee1010 Larry Desjardin

Making the Move Into Modular Instruments

By now, you may have heard the news of Agilent Technologies’ introduction of PXI and AXIe (AdvancedTCA® Extensions for Instrumentationf and Test) modular instruments. It is the largest single introduction of modular products in the history of the company and, perhaps, in the history of the industry. I’d like to add some perspective about this launch, some of the behind-the-scenes thinking that led to this event, and what it means for the industry.

The measurement industry is an essential enabler of innovation, providing critical insight and assurance for development and commercialization of new technologies. The broad variety of applications—from bench use to automated test to manual troubleshooting—demands a range of instrument types to meet these needs.

Agilent is no stranger to modular instrumentation, having offered modular products since the 1970s and having been a driving force behind the VXIbus. However, in the last 10 years, Agilent admittedly has been a minor participant in the open modular space.

With the visible growth of modular instruments, we launched a comprehensive study in early 2009 to determine the key factors that motivated customers and system integrators to adopt modular form factors. The results of this study led to the identification of four key product attributes: cost, speed, flexibility, and size.

Cost was not just price but rather the total cost of ownership including development, service, and support. Speed related to the total test system throughput, which included transactional measurement time as well as burst data rates. Flexibility was the most abstract but still critical concept having to do with open systems, mixing and matching of modules and vendors, reconfiguring test systems, and so forth. Finally, size was principally about reducing rack space since most systems are mounted in an EIA cabinet.

Charting a New Path

With these four attributes in mind, we made a decision to enter the modular marketplace in a major way. To do this, we faced a critical decision: how to organize? Agilent has a wide breadth of technology organized within vertical divisions. Do we concentrate our efforts or keep our investments decentralized?

Ron Nersesian, senior vice president of Agilent and president of Agilent’s Electronic Measurement Group, decided the answer was to form the Modular Product Operation (MPO), a new organization that would wear two hats. It would bring its own products to market and set the architectural and whole product deliverables for any modular product coming from any Agilent division.

MPO defined its own set of modular products and established guidelines specifying software drivers and support for developing modular products anywhere within Agilent. This ensures a high level of consistency among all Agilent modular products. Since products can be developed within any one of our divisions, it enables a large and growing number of modular instruments.

Choosing a Standard

With a new organization established, our attention turned to the question of which modular standard to adopt. Ultimately, the decision was made to standardize on the well-known PXI and new AXIe modular form factors.

PXI was a given, but PXI itself has three manifestations: the original PXI-1 based on PCI, PXIe based on PCI Express, and a hybrid-compatible PXI-1 that uses PCI but has a connector combination that allows it to be inserted into a hybrid-compatible slot. All three have different connectors.

The decision was made that only modules that work in a hybrid slot would be allowed, which meant either PXIe modules or hybrid-compatible PXI-1 modules. If a chassis could be developed with 16 hybrid slots, then any module could be placed into any slot and eliminate all this complexity for the user. This also became a goal.

While PXI was an easy choice because it was so well established, realizing the full promise of modular instruments required creating a new standard for the most demanding and highest power applications. Fortunately, two other companies—Aeroflex and Test Evolution Corporation—were thinking the same thing. Together, we formed the AXIe Consortium ( to create just such a standard. Like VXI and PXI, the resulting AXIe is an industry standard open to all vendors. Today there are eight members of the consortium.

The initial AXIe specification was released on June 30, 2010, seven months after the AXIe Consortium was formed. Essentially, AXIe is the high-performance big brother to PXI. It looks the same as PXI to a host controller and shares the same standard PCIe I/O interface. However, it has more than six times the cooling and board area, all optimized for high-power modular instruments. Additionally, AXIe offers excellent scalability: one to 14 slots, horizontal and vertical configurations, PXI adapters, high rack density, and a local bus capable of data speeds exceeding 600 Gb/s.

We faced a critical decision when determining what soft-ware development environments to support. This can be a key point of vendor control but also customer frustration. Here, the voice of the customer on this issue is unambiguous: support all the development environments. Accordingly, every Agilent module includes IVI-C, IVI-COM, and LabVIEW (G) environment-specific drivers.

Whether Microsoft Visual Studio, .NET, Agilent VEE, MatLAB, LabVIEW, or Excel, the combination of IVI-C, IVI-COM, and LabVIEW software drivers allows you to rapidly develop applications in the environment of your choice. These drivers are optimized to exploit the memory-mapped architecture of PCIe with direct register access to enable the high throughput capabilities of PXI and AXIe.

The Results

At IEEE AUTOTESTCON 2010, we launched modular products that cover the spectrum from DC to lightwave. This list includes a microwave signal analyzer operating to 26.5 GHz with 250 MHz of instantaneous bandwidth, a fast DMM, more than 20 switches, arbitrary waveform generators and digitizers, a digitizing scope, and a BERT and digital communications analyzer capable of performing high-speed optical transceiver test (Figure 1).

Also introduced on the PXI platform was a chassis with 16 hybrid slots and an airflow technique that keeps rack height to a minimum. The hybrid slots enable engineers to freely mix and match PXIe or PXI modules, delivering the flexibility desired by integrators.

We introduced the first instrument capable of working in the AXIe 1.0 environment: a high-speed PCIe Gen 3 analyzer that dissipates up to 150 W in a slot. This is an example of functionality that’s not easily achievable in PXI. Also on display were two- and five-slot AXIe chassis.

Although AXIe is new, I believe it holds a lot of promise for modular instruments. It seems a paradox that the large board area can lead to smaller rack space, but AXIe better utilizes rack depth. The horizontal-oriented chassis offers footprints often smaller than PXI—just 2U for two instrument slots and 4U for five instrument slots, each slot providing 900 cm2 of board space and 30-mm height compared with 160 cm2 and 20 mm for PXI. The two AXIe chassis supply 400 W and 1,000 W of instrument cooling, respectively.

Assessing Success

So what is the outcome of these decisions? Obviously, customers gain access to an expanded choice of modular products and new capabilities that previously weren’t available across analog, digital, RF, microwave, and lightwave technologies. For Agilent and other measurement companies, a modular route may offer an ideal opportunity to deliver breakthrough measurement technology in months instead of years. Finally, the entire industry will benefit because the accelerated growth of the modular market will make it attractive for all vendors and system integrators.

We should remember that the modular instrument segment is just a fraction of the traditional instrument market. A single platform is rarely the right answer for every test scenario. There will be a wider range of choices available to the engineer in both modular and traditional instruments for many years to come. As traditional instruments adopt PCIe as an internal and external communications protocol, I can even imagine the line between them blurring.

About the Author

Larry Desjardin is the general manager of the Modular Product Operation at Agilent Technologies. He joined the company, then Hewlett-Packard, in 1978 as an R&D engineer. Mr. Desjardin also has held various management roles in R&D, marketing, and strategic planning for Agilent’s Electronic Measurement Group. As an R&D manager, he received the John Fluke Sr. Memorial Award in recognition of his contribution to the creation of the VXIbus. The 32-year Agilent/HP veteran holds two patents and earned a B.S. in engineering from the California Institute of Technology and an M.S. electrical engineering from Stanford University. Agilent Technologies, 5301 Stevens Creek Blvd., Santa Clara, CA 95051-7201

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