Keithley embraces PXI
Richard A. Quinnell, Contributing Technical Editor, and Martin Rowe, Senior Technical Editor -- Test & Measurement World, 2/1/2007
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Mark Cejer |
We spoke with Keithley product manager Mark Cejer by phone to discuss the motivation for this new direction at Keithley.
Q: Why did Keithley decide to get into PXI now, nearly 10 years after the introduction of the technology?
A: PXI has started to attain critical mass in our markets. When it was first introduced, PXI tended to target more classic data-acquisition applications of an electrical or mechanical nature. What we are seeing now, however, is that PXI is increasingly being considered by test engineers in the electronics, semiconductor, and wireless industries. So, now our customers are starting to ask for PXI.
Q: Does this mean that PXI is winning the instrument bus war with LXI?
A: PXI and LXI have to coexist and have to be more complementary as opposed to competitive. No one form factor or communication bus can solve every testing need, and we really ought to utilize the best of each. Let the application determine the right kind of approach. Our intention is to use PXI to complement instruments and help test engineers become more productive. By embracing both LXI and PXI, we can work closely with our customers to help them build more optimum solutions to their electronic test applications.
Q: What makes hybrid systems the right approach?
A: Electronics test system builders need the precision of instrumentation as well as the speed of a well-integrated system. Our hybrid offering can provide that precision as well as dramatically speed test time through parallel processing and concurrent execution.
Q: How does it do that?
A: The PXI controller is the system controller, talking with the LXI and GPIB instruments over their buses. Our SourceMeter instruments with TSP test script processor use the GPIB to download a script that the instrument runs each time it is triggered. The GPIB is used only at initialization. A digital I/O card from the PXI tray triggers the instrument during operation to start it executing its script. The SourceMeter output triggers the RF products, which also have sequencing capability. This distributed operation is the key to the throughput improvement. The bus transfer rate is not the bottleneck in electronics test applications. Things like soak time, switch closures, settling times, and mode changes for the device under test are the holdup. Having distributed processing optimizes triggering, timing, and coordination of the overall system to maximize throughput.
Q: Doesn’t this complicate the test-development effort?
A: Yes, but if you try to make things too simple, you end up compromising performance. For our customers, the pressure is intense with respect to profitability, and shaving microseconds off the test time can end up making or breaking their product in the market. They are willing to make the investment to have somewhat more complex programming because the benefits far outweigh the initial cost.
