Test & Measurement World: Production test evolves with PXI

By Richard A. Quinnell, Contributing Editor, Test & Measurement World

In a recent interview, Mike Dewey of Geotest discussed the interaction of JTAG’s boundary-scan controllers with Geotest’s preconfigured PXI test system. -- EDN Europe, 01 Oct 2009

Through a recent collaboration (Reference 1), Geotest–Marvin Test Systems and JTAG Technologies integrated one of JTAG’s boundary-scan controllers into Geotest’s preconfigured PXI test system for the production floor. This suggests that PXI may be moving into new realms in manufacturing test. I spoke with Mike Dewey, Geotest’s senior product marketing manager, to learn more about how this application area is evolving.

Q: What prompted the collaboration?
A: We have been seeing more interest in using boundary scan for production testing as well as for programming of flash memory, CPLDs, and the like on the production floor. JTAG Technologies had PXI boundary-scan products and extensive support software, which made it easy for the companies to integrate their technologies into a preconfigured system.

Q: But hasn’t boundary scan been available on PXI for a long time?
A: Yes, boundary-scan controllers have been available almost from PXI’s inception [in 1997]. But the technology has been mostly used as an adjunct to incircuit structural testing or as a separate test methodology and not as part of a functional-test methodology that PXI systems typically provide. For whatever reasons, combining the two test techniques hasn’t caught on, particularly in the North American marketplace, until now.

Q: Why is combined test catching on now?
A: What has happened is a loss of access to signals on boards and modules due to shrinking feature sizes, buried vias, and the like. This has made bedof- nails probing or in-circuit testing more difficult, so the industry has been moving away from using in-circuit test systems and begun using x-ray and optical inspection as well as other forms of non-contact testing.

The industry has also been leaning more heavily on boundary scan. But if you’re going to eliminate the standalone structural tester, where do you locate the boundary-scan controller? You still need it for some types of structural test as well as for flash and CPLD programming. So, why not add it to the functional tester? The idea has always been there, but now the implementation is moving forward.

Q: What other shifts in manufacturing test using PXI do you see?
A: One surprising area is that PXI is starting to move down from systemand module-level production test into component testing. Component-level test using PXI has been held back by a belief that dedicated ATE systems are needed for speed. But there has been increasing pressure to reduce test cost, and companies are looking for alternatives. This is opening the opportunity for PXI. You may need to give up some speed, but the test system will be significantly lower in capital cost, which could be a compelling tradeoff.

Q: What does PXI need to do to further open up this application area?
A: A lot of what is needed is already happening. PXI Express has become available for moving around the large test vectors that component test requires. The availability of high-performance FPGAs and the lowering cost of memory are also helping, resulting in more costeffective instrumentation. PXI has been missing some things, such as the pin electronics, but this is also changing.

Q: Any other opportunities for PXI?
A: Portable test using compact, ruggedized platforms is on the rise. Such systems are valuable to flight lines, repair depots, motor pools, and other field environments. There are so many functions available in PXI today that it can be a compelling alternative to standalone instruments if the PXI system is robust enough.

REFERENCES

“Geotest teams up with JTAG Technologies on functional, structural test,” Test & Measurement World, June 23, 2009, http://www.tmworld. com/article/CA6666829.html.