PXI Express: more data, faster

Data acquisition has a powerful new tool—PXI Express. What does the new platform mean for PXI, and other board-level form factors, like VME?

PXI Express is the logical next step for PXI. PCI Express was touted as a bus architecture that would converge with a platform like PXI, and this has finally happened, a testimony of how commercial computing technology is put to its best use in the instrumentation world.

What’s it mean for PXI? PXI Express expands the reach that PXI has in certain higher bandwidth applications, especially real-time data-acquisition (DAQ) applications. One notable advantage is getting data streamed to the disk with minimal need for FIFO (first in first out) memory; a development that could eventually turn out to be a cost advantage. In applications requiring higher channel count (for example, beyond 400) with sampling rates close to or above 100MS/s, the need for a FIFO design might still be felt. Because PXI Express offers 45x the bandwidth of PXI, the challenge looks surmountable.

Compatibility

PXI Express is software and hardware compatible with PXI and reportedly offers smooth connectivity between PXI and PXI Express chassis slots. It also incorporates hybrid slots that accept PXI and PXI Express signaling, maintaining sanctity of timing and synchronization.

It would be a natural succession to get products rolling from data acquisition (DAQ) and then move on to other products that deal with higher bandwidth, such as signal sources and digitizers. The first DAQ product releases represent a shot in the arm for DAQ business.

Armed with PXI Express, PXI is expected to move beyond high-speed image acquisition, which saw first adoption of PCI Express in modular instruments in 2004, into application areas such as mechanical structural tests and higher frequency RF tests (currently products in PXI are limited to 6 GHz range).

PXI market reached $118.1 million in sales worldwide and grew 40.2%, according to Frost & Sullivan. PXI Express could provide the required impetus to continue PXI growth at similarly high rates, possibly through 2008. RF testing, one of the fastest growing segments in the PXI market, could benefit by adding a few signal generators in the PXI Express platform, helping PXI scale to higher-frequency applications.

LXI, VXI impacts

It would be inappropriate to treat LXI (LAN eXtensions for Instrumentation; www.lxistandard.org ) and PXI as competing technologies, but many test and measurement vendors believe LXI’s launch will challenge PXI.

Since PXI Express should help PXI nudge closer to certain high-density applications, it may displace some VME Extension for Instrumentation (VXI) applications in military and aerospace markets. Some VXI aerospace applications require a few 1,000-channel-count DAQ systems.

Noise vibration harshness (NVH) could be another market for PXI Express products. In 2004 the NVH test equipment market was valued at $1,079.5 million, according to Frost & Sullivan reports, showing a large potential opportunity for modular instrument vendors and PXI vendors.

Karthik R., program manager, Frost & Sullivan, www.frost.com .

PXI Express facts

The PXI Express specification:

Integrates PCI Express and CompactPCI Express technology into the PXI instrument-interface standard;

Offers bandwidths up to 6 GB per second per system, representing a 45-fold improvement when compared to traditional PXI systems, while preserving software and hardware compatibility with more than 1,150 existing PXI products;

Derives from PXI and is backward compatible with it; and

Defines hybrid slots for compatibility for a new Hybrid Slot Compatible PXI-1 Module, 32-bit CompactPCI board, and PXI Express Peripheral Board modules. (Existing PXI boards would need to plug into a PXI slot)

From Control Engineering news item, “PXI takes the Express,” Aug. 18, 2005. Learn more at

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