Today, with the diversification and increasing complexity of testing needs, software-defined instrumentation systems have become the most important development trend and mainstream technology in the test and measurement industry. Software-defined modular systems not only help users improve efficiency while reducing testing costs, but also meet the needs of future upgrades and expansions.
Software-defined modular testing systems have become the mainstream technology in the industry.
Today's electronic products (such as the iPhone) not only integrate more and more functions, but also rely more and more on software to define product functionality. Similarly, with increasingly complex product design and customer needs, the role of software-defined instrumentation systems for test and measurement is becoming increasingly prominent. By defining hardware functionality through software, users can configure test systems more quickly and flexibly to meet ever-changing test requirements. For example, the same digitizer can perform different functions such as an oscilloscope, spectrum analyzer, and video analyzer. In addition, software can also be used to customize more user-friendly human-machine interfaces.
Meanwhile, in order to test the multiple functions integrated into electronic products, and to achieve better flexibility and upgradeability, testing systems are gradually developing towards modularity and smaller size. This means simplifying complex testing systems into modular hardware and software to be implemented one by one. When additional test items are needed, only the corresponding functional modules need to be added to meet future upgrade requirements.
Based on these two development directions, software-centric modular instrument technology has emerged and become the most important development trend and mainstream technology in the test and measurement industry. Compared to the fixed functional configuration of traditional instruments and their mere presentation of "test results," software-centric modular instrument technology gives users more customized measurement functions. Commercial high-speed buses (such as PXI/PXI Express) can ensure the transmission of large amounts of raw data; once the raw data is acquired, the powerful functions of the software can be utilized to perform customized processing, analysis, display, report generation, or data storage of the raw measurement data. For example, by configuring modular RF instruments using software and combining them with custom software modulation and demodulation, testing of multiple wireless protocols can be achieved on the same hardware platform, which embodies the concept of software-defined radio.
A five-layer modular instrument architecture with software at its core.
Specifically, a detailed modular testing system architecture centered on software is shown in Figure 1. Many enterprises now use this architecture as a standard for building their testing systems.
Figure 1. Five-layer architecture of a software-centric modular testing system
Structure Level 5: System Management Software
The system management software layer sits at the top of the five-layer architecture. For an automated testing system, some test tasks differ depending on the device under test (DUT), such as instrument configuration and result analysis; while others are common to all DUTs, such as test process management and test report generation. The role of test management software is to separate these common tasks, creating test processes, integrating report generation, and database management functions through specialized software services. Professional test management software (such as NI TestStand) not only provides the above functions but also includes built-in parallel and automated coordinated testing tools to help users significantly improve testing efficiency and increase system throughput.
Structure Level 4: Application Development Software
Application development software plays a crucial role in the test architecture, acting as a bridge between different components. System developers use it to implement specific measurement applications, display necessary information to end users, and connect to other applications; simultaneously, the test development software needs to connect to I/O via device drivers. Furthermore, the software used to develop measurement applications needs to integrate powerful data analysis and reproducibility capabilities and be mainstream software with a long lifecycle. NI's graphical programming software, LabVIEW, provides users with efficient and intuitive test and measurement application development tools that meet all these requirements. For users accustomed to text-based programming, ANSI C-based LabWindows/CVI and Microsoft Visual Studio-based Measurement Studio are also good choices.
Structure Level 3: System Services and Drivers
The system services and driver layer serves as the link between the software development environment and hardware devices. Beyond acting as device drivers, this layer should encompass more functionalities such as hardware configuration management and diagnostic testing. For example, NI Measurement and Automation Explorer (MAX) software helps developers perform unified, automated detection and configuration of all NI hardware and numerous traditional instruments connected via the bus. System services and drivers also provide integration with the application development software layer through application programming interfaces (APIs), allowing developers to easily program devices, thereby improving development efficiency and reducing maintenance costs.
Hierarchical Structure Level Two: Processing Bus Platform
There are many types of instrument buses, each with its suitable applications. For example, the GPIB bus is still the most common control bus for benchtop instruments; the LAN/LXI bus is particularly suitable for distributed systems. To leverage the advantages of different buses and optimize system performance, many test applications are based on hybrid bus test systems. As an open, PC-based test and measurement platform, PXI and PXI Express offer industry-leading data bandwidth performance and backplane-integrated timing and synchronization capabilities, ensuring that using them as the core bus will not become a bottleneck in the overall hybrid system. Furthermore, PXI and PXI Express have hardware and software interface support for interconnecting with various other buses, making them ideal choices for the core bus of hybrid bus test platforms.
Structural Level 1: Instrument and Equipment I/O
As the lowest layer of the system architecture, the instrument and device I/O layer directly interacts with the actual physical signals, performing tasks such as signal conditioning, A/D and D/A conversion. Modular I/O primarily utilizes instruments based on PXI and PXI Express buses. Currently, over 70 manufacturers offer more than 1,500 types of PXI modular instruments, including many well-known companies such as Agilent, Rhode & Schwarz, Keithley, and NI, covering a wide range of I/O modules from digitizers, signal generators, RF components, power supplies to switching modules. Based on the modular software architecture and PXI/PXI Express-centric control modules, users can also easily integrate traditional instruments based on GPIB, USB, LAN/LXI buses, etc., preserving their original investment value.
Application of modular testing system architecture with software at its core
Today, thousands of companies have adopted software-centric modular system architectures as the standard for building instrumentation systems. For example, Microsoft designed a test system for the Xbox 360 controller based on NI LabVIEW and PXI modular instruments, which is twice as fast as its predecessor. Hualu Panasonic developed a complete automated test system for its new DVD burner using NI TestStand, NI LabVIEW, and modular instruments, significantly improving efficiency. These examples are numerous. Adopting a software-centric modular architecture not only accelerates test system development time and saves costs, but also allows for the introduction of the latest commercial technologies, creating innovative applications. These applications include parallel testing based on multi-core processors, custom instrument design and hardware-in-the-loop simulation based on FPGAs, and high-speed data transfer based on PXI Express bus and disk array technology. It is believed that software-centric modular architecture will remain the mainstream of testing technology in the future, continuously penetrating every testing field and expanding into new application areas.
