Three Strategies for Maximizing Test System Efficiency
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Test engineers are facing new pressures to develop high-performance test systems that maximize efficiency.
Despite rapidly increasing device complexity, test engineers have to deliver higher-speed and lower-cost test systems and now must consider the requirements of their corporate sustainability programs. These corporate sustainability programs often have goals of reducing energy consumption, carbon footprints, and emissions. Some examples from corporate sustainability programs include the following:
- Flextronics’ goal is to protect the environment, conserve energy and natural resources, and prevent pollution by applying appropriate management practices and technology
- Delphi has established goals to further reduce energy usage at its plants around the world
- Samsung promises to continue minimizing the use of resources and energy through clean production technologies
Many manufacturing and engineering teams are now given sustainability targets with the goal of using resources more efficiently. By applying the following three strategies, you also can meet your objectives of increasing test system efficiency:
- Reduce test times by maximizing instrument utilization
- Increase instrument longevity with reuse
- Use more energy efficient instrumentation
Reduce Test Times By Maximizing Instrument Utilization
Increasing the throughput of an automated test system delivers efficiency gains. By using commercial off-the-shelf (COTS) tools suchas multicore processors, PCI Express, field-programmable gate arrays (FPGAs), and NI LabVIEW software, you can create parallel processing and parallel measurement systems capable of testing a single unit under test (UUT) with the shortest possible test time. One technique for further maximizing efficiency is adopting a parallel test strategy on multiple UUTs. Parallel test clearly reduces aggregate test times and improves instrument utilization (see Figure 1), but the complexity of developing a parallel test system can be prohibitive. Developing your own test management software that implements the testing of multiple UUTs at once requires a low-level understanding of parallel programming and multithreading.
An alternative to developing a custom parallel test system from scratch is to use off-the-shelf test management software, such as NI TestStand. NI TestStand abstracts the low-level complexity of parallel test system development using built-in features for executing parallel test sequences in multiple threads and managing both the OS and instruments.
Figure 1. Increase tester efficiency by testing multiple UUTs in parallel.
Increase Instrument Longevity with Reuse
By developing reusable systems, engineering teams can maximize instrument utilization while extending the life of their test systems. A reusable automated test system should be based on a flexible, modular hardware platform, such as PXI, which you can reconfigure in software to test multiple product generations and even different types of products. An example of an NI customer realizing the benefits of a modular, software-defined test architecture is Benchmark Electronics.
Benchmark Electronics, a leading electronics contract manufacturer, developed a standard test platform to maximize the reuse of existing assets to test a wide range of product categories. The reusable tester can accommodate a variety of board- and device-level parametric and stimulus-response tests. The standard instrumentation system includes a PXI chassis, MXI controller, digital I/O, digital multimeter (DMM), digitizer, and function generator (see Figure 2). Depending on the test requirements, Benchmark Electronics has ample room to add instruments for specific needs without disrupting the standard instrument suite because of the flexible software framework based on NI TestStand and LabVIEW. Benchmark Electronics has realized efficiency gains by reusing test systems over the development of a wholly new test solution.
Figure 2. The Benchmark Electronics tester is optimized for reuse with a PXI chassis and other modular instruments.
Use More Energy Efficient Instrumentation
A recent energy study revealed that the nation’s largest energy consumer, the U.S. federal government, could save more than $1 billion in power costs over the next five years by switching to greener technologies. “Energy costs are a growing concern for tech managers nationwide,” Pat Tiernan, vice president of social and environmental responsibility at Hewlett-Packard, stated in response to this study. While the average electronics manufacturing facility may use more energy in other parts of the process, test still has to play its part in minimizing energy use. Evaluating the tools test engineers use shows that a large portion of energy consumption is due to the instrumentation used in a test system. Today, there are two major options for building automated test systems – PXI and rack-and-stack instrumentation. Analysis of a comparable mixed-signal system on each platform reveals that a PXI system consumes 60 percent less power than a rack-and-stack system (see Figure 3).
Figure 3. A PXI system with DMMs, signal generators, digital I/O, oscilloscopes, and RF modular instruments uses 60 percent less power than a comparable rack-and-stack system.
The primary factor for the difference in power consumption is that all modular instruments in a PXI system share the same power supply, chassis, and controller. Rack-and-stack instruments, however, duplicate the power supply, chassis, and controller in every instrument, which dramatically increases their power consumption. Because of its reduction in power consumption, a PXI system can reduce your energy costs by more than $2,000 USD over five years for each test system, in one analysis. In a factory with 100 testers, this energy savings could be as much as $85,000 USD per year.
Cost is not always the only reason for reducing energy consumption. In fact, many organizations receiving electricity from fossil fuels are also focusing on reducing their carbon footprints and emissions. The lower energy consumption PXI offers can actually have a larger impact by reducing carbon emissions. Every PXI system that displaces a rack-and-stack system reduces carbon emissions by 5,925 lb per year, which is nearly half the amount of carbon emitted by an automobile each year (the average American car emits 12,100 lb per year).
Performance and Sustainability
Manufacturing test has an evolving role to play in helping manufacturers reduce their impact on the environment by increasing throughput, maximizing reuse, and minimizing test system energy consumption. Test system performance gains do not come at the expense of sustainability; in fact, they help drive it.
Kevin Bisking is a senior product manager for the NI test platform. He holds a bachelor’s degree in electrical engineering from The University of Texas at Austin.
Read an in-depth white paper about these three strategies and comparison details.
This article first appeared in the Q2 2008 issue of Instrumentation Newsletter.
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