Building the next generation of software-centric automated testing systems

　　1. Introduction: Design Challenges of Automated Test Systems

　　To ensure the quality and reliability of products delivered to customers, test managers and engineers use automated test systems in a variety of applications, from design verification, end-product testing, to equipment maintenance diagnostics. They use automated test systems to perform simple "pass" or "fail" tests, or they use them to perform a complete set of product characterization tests. As the cost of detecting product defects late in the design cycle is rising, automated test systems are quickly becoming an important part of the product development process. This article, "Designing the Next Generation of Automated Test," describes some of the challenges that force engineering teams to reduce testing costs and time. The article also provides insight into how test managers and engineers can overcome these challenges by building modular, software-defined test systems. This test system significantly increases the throughput and flexibility of the test system while reducing overall costs.

　　Today's test engineers face a new set of pressures. The product development environment they face is as follows:

　　Product designs are more complex than previous generations
　　. Development cycles are required to be shorter and shorter in order to remain competitive and meet customer requirements.
　　Product testing costs are increasing, while budgets are shrinking.

　　Increasing design complexity

　　Today, the most obvious trend in test and measurement is the increasing complexity of devices. For example, the consumer electronics, communications and semiconductor industries continue to require the integration of digital images/video, high-fidelity audio, wireless communications and Internet connectivity into a single product. Even in cars, complex automotive entertainment and information systems, safety and early warning systems, and control electronics on the body and engine are integrated. The design of the test system not only needs to be flexible enough to support a wide range of tests on different product models, but also needs to be able to be upgraded to provide more test points required for new test functions.

　　Shorter product development cycle

　　Due to the competitive nature of wanting to continuously improve new products and technologies and have the first market share, the design and test engineering team can only continuously shorten the product development cycle. To this end, the engineering team must design new test strategies to reduce test time and improve test efficiency from design to production.

　　Increasing test costs and decreasing test budgets

　　Adding device functionality usually results in a more expensive and time-consuming test process. However, the cost of building each function is decreasing, which forces engineering departments to reduce costs and budgets, as shown in Figure 1. Engineers must improve test strategies to reduce total costs by increasing test system throughput, reducing maintenance and upgrade costs, and reducing required capital investments.

　　2. Increasing test costs and decreasing test budgets

　　To meet the challenges of increasing device complexity, shortened development cycles, and reduced budgets, test managers and engineers are forced to abandon traditional test design strategies based on traditional box instruments or "big iron" proprietary ATE systems. These stand-alone instruments lack the flexibility necessary for software processing, and the user interface is defined by the manufacturer and can only be updated by the manufacturer through firmware. This makes it difficult to execute tests that are not defined in the instrument firmware and tests for new standards; or to modify the system when requirements change. Because these devices were originally designed as stand-alone instruments, they lack necessary integration capabilities, such as data streaming and synchronization functions. Proprietary ATE systems (such as highly integrated product chip testers) can provide the required performance, but the cost is quite expensive, which may cause engineering teams to abandon and redesign the system prematurely.

　　In response to these situations, test managers and engineers are implementing a modular, software-defined test architecture based on widely adopted industry standards that provides:

　　· Higher test system flexibility: scalable to multiple applications, business units, and various product stages
　　· High-performance architecture: can significantly improve test system throughput and provide close connection and integration with different instrument vendors, including the generation and analysis of precision DC signals, high-speed analog and digital signals, and RF signals.
　　· Lower test system investment: reduce initial capital investment and maintenance costs, while increasing equipment utilization in a variety of test requirements
　　· Longer test system life: based on widely adopted industrial standards, allowing technology upgrades to improve performance and meet future test needs

　　As a leader in automated test, NI is committed to providing product engineers with the hardware and software they need to design the next generation of automated test systems. This in-depth developer's guide contains the information needed to design the next generation of automated test system architecture. The introduction describes a test system architecture as shown in Figure 2, providing engineers with strategies to cope with a series of challenges such as increasing device complexity, shortened development cycles, and reduced budgets.

　　3. Hierarchy 5: Automated Test System Management Software

　　Automated test systems need to implement a variety of tasks and measurement functions: some of these tasks and functions are related to the device under test (DUT), while others are common to each DUT. In order to minimize maintenance costs and ensure the life of the test system, it is very important to implement a test strategy that separates DUT-level tasks from system-level tasks, so that engineers can quickly reuse, maintain and modify test programs (or modules) throughout the development cycle to meet specific test requirements.

　　In all test systems, there are different operations depending on the device under test, and there are also operations that are common to all devices under test, such as system-level tasks.

　　Some companies have written their own test executives and allocated valuable engineering resources to develop test management software from scratch. This often results in lost productivity and long hours of tied up resources maintaining the software. To maximize productivity, engineering teams should leverage commercially available test management software, such as NI TestStand software, to reduce the development of common operations for each device. By leveraging this software, engineers can focus on the development of proprietary operations for each device.

　　4. Structural level 4: application development software

　　In the test system architecture, application development environments (ADEs), such as NI's LabVIEW and LabWindows/CVI, play a key role. With these tools, test system developers can communicate with a variety of instruments, integrate measurements, display information, connect to other applications, and so on... The ideal ADE for developing test and measurement applications needs to provide a series of application requirements such as ease of use, efficient compilation performance, integration with a variety of I/Os, and programming flexibility. Ease of use is not only about how quickly you can get started and use it. With easy-to-use ADEs, developers can easily integrate processing routines with a variety of measurement devices, create complex user interfaces, deploy and maintain applications, and modify applications when product designs are improved and system needs are expanded.

　　5. Structural level 3: measurement and control services

　　Measurement and control services provide connectivity, system configuration, and diagnostic tools to various hardware resources in the system, which is critical. For example, NI Measurement and Automation Explorer (MAX) can automatically detect hardware resources, including data acquisition, signal conditioning hardware; GPIB, USB, and LAN-controlled instruments; PXI systems, VXI devices; modular instruments, etc., so developers can configure them in one place. Integrated diagnostic tests ensure that the device functions properly, and test panels provide developers with a quick way to check the functionality of the hardware before starting programming. Measurement and control services also provide integration with the application development software layer through application programming interfaces (APIs), so that developers can easily program their devices. In fact, the components of this service software - hardware drivers, application programming interfaces (APIs), and configuration managers must be seamlessly integrated into the ADE to maximize performance, improve development productivity, and reduce total maintenance costs.

　　6. Structural level 2: calculation and measurement bus

　　At the heart of every automated test system is a computer (in the form of a desktop PC, server workstation, laptop, or embedded computer that works with PXI and VXI, etc.). An important aspect of using a computing platform is the ability to connect (and communicate) with a wide variety of instruments in the test system. There are many different instrument buses available for standalone or modular instruments, including GPIB, USB, LAN, PCI, and PCI Express. These buses have different capabilities, and some are more suitable than others for specific applications. For example, the GPIB bus is widely used in instrument control and has wide availability for instruments; the USB bus offers wide availability, easy connectivity, and high throughput; the LAN bus is very suitable for distributed systems, and the PCI Express bus provides the most efficient performance.