Test engineers are facing new pressures to develop high-performance test systems that maximize efficiency. Despite rapidly increasing device complexity, they have to deliver higher-speed and lower-cost test systems, as well as contribute to corporate sustainability programs. This pressure is exemplified by the addition of corporate responsibility and sustainability programs presented on almost every corporate Web site. These corporate sustainability programs often have goals of reducing energy consumption, carbon footprints, and emissions.

Here are some examples from corporate sustainability programs:

  • Lockheed Martin adheres to a “Buy Smart, Use Less” business model.
  • 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 our plants around the world.”
  • Samsung “will continue to minimize 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. This article provides three proven strategies for increasing test system efficiency.

Strategy 1: Reduce Test Times by Maximizing Instrument Utilization

Figure 1. Test efficiency can be maximized by adopting a parallel test strategy that simultaneouslytests multiple UUTs in parallel.

Increasing the throughput of an automated test system produces efficiency gains. For years, engineers have em - ployed numerous strategies to extract more speed from their systems in both R&D laboratories and on the manufacturing floor. These optimization techniques have often included brute-force procedures, such as cutting down the number of tests and purchasing redundant instruments. In the end, there are proven strategies for maximizing throughput without having to make such sacrifices. By using commercial off-theshelf (COTS) tools such as multicore processors, PCI Express, field-programmable gate arrays (FPGAs), and 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.

For high-volume applications, you can further maximize efficiency by adopting a parallel test strategy that simultaneously tests multiple UUTs. Parallel test clearly reduces aggregate test times, increases test throughput, and improves instrument usage (see Figure 1). The complexity and cost of developing a parallel test system has historically been prohibitive. Developing test management software that implements the testing of multiple UUTs at once requires a low-level understanding of how the operating system works with parallel operations, such as Windows Critical Sections, and careful consideration of how to implement instrument sharing among many UUTs without creating conflicts or deadlocks.

An alternative to developing a custom parallel test system from scratch is to use off-the-shelf test management software, which 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 operating system and instrument resources.

Strategy 2: Increase Instrument Longevity through Reuse

By developing reusable systems, you can maximize instrument utilization while extending the life of your test systems. By definition, you can reconfigure (in software) a reusable test system to test multiple product generations and even different types of products. With the short life span of products today, it can be wasteful to build testers for specific generations. However, one of the biggest roadblocks to developing a reusable/flexible tester is the actual test system architecture. A modular test system architecture helps you gain the maximum reuse because you can:

  • Incorporate existing/legacy test routines into the new system with minimal rework.
  • Introduce future test routines into the system without a complete system redesign.
  • Quickly replace individual instruments and I/O devices.
Figure 2. A PXI system with DMMs, signal generators, digital I/O, oscilloscopes, and RF modular instrumentsuses 60% less power than a comparable rack-and-stack system.

The key step in developing a reusable test system is to exam your test software framework. This includes evaluating your software management and development tools and studying your test code development approach. Understanding the importance of modular test software architectures and how to develop your tests as modules, rather than building stand-alone applications, significantly improves your test software reuse.

Selecting test and measurement hardware with robust software interfaces is another important consideration in defining modular software architectures. Measurement and control services software provides modular hardware interfaces for configuring and programming your test system through the use of virtual channel names, virtual devices, and simulation interfaces. Such modular measurement and control services driver software helps you avoid developing test programs that are permanently tied to specific hardware and channels in your test system, thus increasing the ease of code and instrument reuse.

The last step in creating and maintaining a flexible system is implementing a system architecture that transparently accommodates multiple bus technologies and uses an open, multivendor hardware platform to achieve I/O connectivity. With the proper computer platform and driver, application, and test system management software, you can combine the strengths of many types of instruments, including legacy equipment and specialized devices. It is important to fully recognize that no single platform or bus technology meets all needs, though each has unique strengths.

Strategy 3: 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.

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 the 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-andstack instrumentation. Analysis of a comparable mixed-signal system (composed of DMMs, oscilloscopes, signal generators, RF instruments, and digital I/O) on each platform reveals that a PXI system consumes 60% less power than a rack-and-stack system (see Figure 2).

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, choosing a PXI system can reduce energy costs by more than $2,000 USD over five years for each test system (assuming typical usage of 16 hours/day for 315 days/year).

Companies with more than one tester realize larger savings. Cost is not always the only reason for reducing energy consumption. In fact, many organizations that run on electricity from fossil fuels are also focusing on reducing their carbon (CO2) footprints and emissions. The reduced energy consumption by choosing PXI can actually have a larger impact by reducing (CO2) emissions.

Every PXI system that displaces a rackand- stack system reduces the CO2 emission by 5,925 lb./year, which is nearly as much as half the amount of CO2 emitted by an automobile. It is estimated that more than 50,000 PXI systems were deployed from 1998 through 2006. The reduced emissions from these PXI test systems have effectively reduced the carbon footprint at a rate equivalent to removing 17,144 cars off the road. The impact of the reduced PXI carbon footprint will only increase as the number of deployed PXI systems grows over the next five years, based on the forecasted CAGR for PXI.

It’s likely that an increasing number of manufacturing and engineering teams will be given sustainability targets with the goal of using resources more efficiently. 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.

This article was written by Kevin Bisking, senior product manager for the NI test platform at National Instruments, Austin, TX. For more information, Click Here .


NASA Tech Briefs Magazine

This article first appeared in the August, 2008 issue of NASA Tech Briefs Magazine.

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