Freedom of Choice in Platforms

This year (2011) has seen three test platforms continuing to develop their market message and attract new users from older platforms such as GPIB and VXI, the choices seem to continue to expand for users. From a professional and a business standpoint, we see the choices as good for both vendors and customers as it allows for a broader range of applications to be supported by a greater number of products and platforms that address every budget and requirement. In this short article, we point out where the various platforms appear to be headed and why, from a Pickering standpoint, the freedom of choice is a good thing.

LXI Milestone

The LXI Consortium has announced that by May 2011 it has certified more than 1,500 products from 35 different vendors since products were first launched in December 2005. That is particularly impressive since the consortium requires third party certification of LXI Devices to ensure vendors maintain the interoperability standards set by the specification for Ethernet (LAN) controlled instruments. What does that mean for the vendors and users of LXI products? First of all, it certainly ensures that complete test systems can easily be assembled with a number of LXI products. Second, certification reinforces the robustness of the Ethernet interface and its widespread availability on computing platforms and ensures that it has the same feel and stability associated with GPIB systems. For vendors, it validates that their product line is compatible with all LXI products.For Pickering Interfaces the core of our business is PXI based switching systems, but we have invested heavily in the LXI platform for good business reasons.

Doing the impossible in LXI

Many of our dedicated LXI solutions were simply impractical to implement in a PXI form factor. PXI imposes modular mechanical constraints on product design and when there is a requirement for a large and/or very complex switching system, it simply will not fit. Creating a crosspoint matrix for example with 4,000 off 2A rated relays requires a great number of modules to be interconnected, often completely filling or exceeding the capacity of a single PXI chassis. Some products require the use of large components such as microwave relays which simply take too much of the space in a PXI chassis, in doing so inflating the real cost of the switch and taking up valuable rack space. 

Each PXI module has its own overhead from the PCI interface it carries and the slots it occupies in the chassis.In comparison the LXI platform requires its own LAN controller interface - Granted, a higher cost than the PCI interface on PXI - and its own case system to support its switch payload which is typically much lower cost than the PXI chassis. An added advantage is that external cabling is usually greatly simplified as any inter-module is eliminated as it is handled internally, In the case of a large complex switching application, the overall cost advantage can be a 40% saving or even more.So for Pickering Interfaces the advantages of LXI are clear, they enable us to provide switching systems with LXI which are hard, impossible or uneconomical to do in PXI. It is not just switching systems these arguments apply to, in almost all product categories of test and measurement there are clear differences in what can be achieved in one platform compared to another. The differences may lie in measurement traceability, accuracy or particular areas of performance and they vary from one category to another. Control distances and and robustness of the connection can also be an important - and LAN connections excel in this area because to their IT heritage.

PXI Growth

PXI continues with its own milestones and the entry into this market of Agilent (now Keysight) Technologies is certainly a very major event that will ensure the continued adoption of that platform into wider markets. We believe it is a very welcome event and one that will help expand the overall PXI market size and increase its adoption as the primary modular standard. ThePXI standard also continues to evolve as work has now starting and standardization of the backplane trigger function API . PXI remains the dominant implementation of the standard (relative to PXIe) in both modules and chassis, but there are applications where PXIe makes more sense because of the need to transfer large files into or out the modules. For applications where PXIe modules are required the use of hybrid chassis that support both versions of the standard (PXI and PXIe) makes clear sense since module choice is much broader in PXI than PXIe and is likely to remain so, particularly for Pickering Interfaces core switching products.The platform of choice for applications where the backplane speed of PXIe is likely to be Hybrid chassis where the slots (with the exception of the controller and timing slots) can accept either PXI or PXIe modules. Such a chassis is always likely to be a premium product since it has to support both types of power source and both types of control interface (PCI and PCIe).


PXI is not the only modular standard that is growing. AXIe also has its adopters for higher performance systems and has embedded interfaces based on aspects of both LXI and PXI.


More options on the platform of choice arise with Pickering Interfaces supporting its PXI switching modules in an LXI controlled modular chassis, so Pickering PXI switching modules can be placed in an LXI or a PXI controlled environment.


It is unusual to have three relatively new (in terms of test and measurement) standards making market progress at the same time, but it seems the future for test and measurement is principally with these growing instrumentation standards. Users have more choice, that is good news for the industry and vendors have the opportunity to promote the platform that best suits their products knowing that all three standards will have their place in test systems.

By David Owen and Bob Stasonis. This appeared in many publications as a commentary during 2011.

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