Development Trend of Virtual Instrument and Its Impact on Military Testing Technology
2021-07-08 12:06:42
Abstract: Since 1986, NI company proposed VI concept to the present, after more than ten years of development, not only the connotation of VI technology itself has been continuously enriched, the extension has been expanding, it has been widely used in military and civilian fields, and it is also applied to modern measurement and control technology. It has a profound effect. This article mainly introduces the development trend of virtual instruments and their impact on military test technology to the readers.
1. Introduction Since the VI concept proposed by NI Corporation in 1986, now after more than ten years of development, not only the connotation of VI technology itself has been continuously enriched, the extension has been continuously expanded, and it has been widely used in military and civilian fields, and it has also been applied to modern monitoring and control. Technology has had a profound effect. For example, the original core idea of ​​the VI was to make use of the computer's powerful resources to software that would otherwise require hardware implementation in order to minimize system costs and enhance system functionality and flexibility. It is determined by the characteristics of the IT industry that the VI technology must also take the standardization and openness of this technical route. At present, VI has developed into an open technology with four standard architectures: GPIB, PC-DAQ, VXI, and PXI. In 1998, NI released the concept of Virtual Hardware and Interchangeable Virtual Instruments. Products designed according to the VH concept were already available, such as (NI5911, NI5912), and the IVI Foundation was established in 1998. It was formally established in the United States in August and published the corresponding IVI technical specifications. The application program developed based on IVI technology is completely independent of the hardware, improves the reusability of the program code, greatly reduces the maintenance cost of the application system, and is bound to become one of the main basic technologies of the measurement and control technology.
As for the extension of the VI, since the VI technology itself uses a computer as a platform and has convenient and flexible connectivity, it widely supports various industrial bus standards such as CAN, DeviceNet, FieldBus, PROFIBUS, etc. Industrial distributed I/O (Distributed I/O) products are on the market. Although Internet technology did not initially consider how to connect embedded smart devices together, companies such as NI have developed products that use a Web browser to view these embedded devices so that people can operate instruments and devices through the Internet to form home-based devices. Distributed measurement and control networks in offices and industrial sites. Moreover, standards related to MCN (Measurement and Control Networks) are actively being implemented and some progress has been made. With the further networking of measurement and control processes, a truly virtualized monitoring and control era is approaching.
2. The idea of ​​virtual hardware virtual hardware (VH) originates from the programmable device, which enables the user to easily change the function or performance parameter of the hardware through the program, thereby relying on the flexibility of the hardware device to enhance its applicability and flexibility. For example, NI5911/5912 is a high-speed (100MS/s), high-precision (8-21-bit), and flexible data acquisition device designed according to this idea, and its sampling rate and accuracy are variable. Since the general ADC is a user variable sampling rate, the following introduces the flexible resolution technology used in the NI5911/5912.
The so-called flexible precision technology consists of a specialized digital filter, high-speed ADCs, DACs, and DSPs for decimation and linearization (as shown in Figure 1). For 4 to 100 MHz bandwidth signals, the system can use a conventional method to operate at a real-time sampling rate of 100 MS/s with 8-bit accuracy. When the bandwidth of the measured signal is below 4 MHz, flexible precision can be used to achieve effective vertical accuracy. Achieve 21-bit. In the flexible precision mode, the wide-band quantization noise in the sampled signal is filtered out by the noise forming circuit, then the data is sent to the DSP for linearization, and the anti-aliasing filter in the DSP is further used to filter out the high-frequency noise and finally extracted. The technology reconstructs the waveform at a lower rate, resulting in an effective vertical accuracy of 8 to 21 bits. It should be pointed out that all signal processing is done in real time on the 100 MHz data stream. This ensures that no data will be lost during the acquisition and processing.
3. Graphical and Zero Programming Development Environment The rapid update of the VI system and the online update of its testing process are forming trends in the world. The standardization and serialization of instrument buses has created good hardware conditions for the rapid formation of ATE systems. Another aspect of the problem is how to implement rapid on-line programming of test software to meet the ever-changing test requirements. The graphical and zero programming development environment was born to meet this demand.
3.1 Architecture of the Graphical Development Environment The graphical development environment, also known as the G development environment or the G language (Graphical Language), is increasingly familiar and used by more and more test engineers. The following uses NI LabVIEW as an example to introduce the architecture of the graphical development environment.
As shown in Figure 2, a complete G development environment (Full Development System) consists of two parts, BasePackage and ExtensionPackage. The engine part is the core of the entire graphical development environment. It includes edit modules, run modules, and debug modules.
The LabVIEW development environment is divided into a front panel (frontpanel) and a flowchart (blockdiagram). The former is a graphical user interface (GUI) for human-computer interaction, and integrates user input (control) objects such as knobs and switches; It is the graphical source code of the program. It includes functions, structures, terminals on the front panel and display objects, and connections. The function of the editing module is used for programming the front panel and the flow chart, and the graphical element library is used to edit and debug the tools of the front panel and the object on the flow chart. The functions and functional modules used in the control and display objects and flowcharts used in the front panel (such as arithmetic operations, instrument I/O, file I/O, and data acquisition operations) and the running modules are the engines of the programs. The debug module includes "highlight execution", "set breakpoint", "probe", and "single step" debugging tools, the most distinctive of which are "highlight execution" and "probe". "Probe" is used to display the value of a variable online while the program is running, and "execution highlighting" is used to track the flow of data during program execution. The instrument interface module includes VISA library, GPIB library, serial port library, DAQ library and VXI library. The programs in the Instrument Driver Library are application source code provided by NI and its system alliance members or hardware vendors to control a specific instrument to simplify the application engineer's program development process. The advanced analysis library is used to increase the program's data processing capabilities, including signal generation, DSP, measurement, digital filtering, windowing, curve fitting, probability and statistics, linear algebra, matrix operations, and various additional numerical methods.
3.2 Architecture of a Zero Programming Development Environment The G development environment utilizes terms, icons, and concepts familiar to scientists and engineers and uses graphical symbols rather than textual instruction codes to describe the behavior of the program. Therefore, it provides people with the means to implement the instrument. Easy way of programming and data acquisition system. Even so, in the field of industrial automation, there are open standards such as OPC (OLR for Process Control) and Foundation FieldBus, and application engineers need to develop human-machine interface (MMI) or supervisory control and data acquisition (SCADA) with many common features. In order to shorten the program development cycle and improve program quality, National Instruments introduced BridgeVIEW, a software development environment that combines G development environment features and zero programming features.
As shown in Figure 3, BridgeVIEW is a client-server architecture consisting of three parts: MMI/SCADA, Engine, and Device Server. MMI/SCADA is a user-developed application that includes GUIs, monitoring programs, data analysis and visualization, and process real-time control. The development of MMI/SCADA can be done either with the previously described G language or with so-called Tag tags. Configure tag properties such as I/O points, parameters, history data records, and alarm events that you need to access by tagging and programming without programming. The application exchanges data by sharing the real-time database with the engine. The device server collects tag values ​​and status information in real time and passes them to the engine. It should be noted that the application, engine, and device server operate separately in BridgeVIEW and therefore can achieve high operating speeds.
4. Interchangeable virtual instruments If you change the operating system or instrument hardware for years, you must revisit the test program. Although cross-platform development environments such as LabVIEW and LabWindows/CVI as described in the previous section ensure that changing the operating system does not require modification of the test program, the replacement of hardware devices (such as changing HP's DMM to Fluke's DMM) requires modification of the test program. This problem is caused by the lack of uniform standards among device drivers of different hardware vendors. The purpose of the IVI Foundation is to develop new instrument programming standards so that applications are completely independent of hardware devices.
The core of the IVI specification is the IVI device driver library. The library divides the drivers for all devices into five categories of oscilloscopes, multimeters, signal sources, switches, and power supplies. It defines a standard programming interface for communicating with each type of instrument. It is impossible for all instruments in each class to have exactly the same function or capability. Therefore, it is unrealistic to specify a unique standard interface to ensure that all instruments in the same category can work properly. The IVI specification divides each type of instrument driver into basic capabilities (fundamental capabilitices) and extensions (extensions). The former defines the capabilities and attributes common to more than 95% of the instruments in the same instrument; the latter defines many of the special features and attributes of each instrument.
The standard instrument class driver works in a "virtual" way. For example, the application calls IviDmm-Configure instead of calling FL45-configure or HP34401-Configure directly. In this way, when the system is using the FL45DMM, the program will be automatically loaded into FL45-Configure dynamically during operation. If you later replace the FL45DMM in your test system with the HP34401DMM, the IviDMM driver automatically directs you to call HP34401-Configure. According to this "virtual" approach (as shown in Figure 4), the differences in the characteristics of different instruments in the same type of instrument are "shielded" to ensure that the application program is completely independent of the hardware device, that is, to ensure the interchangeability of the instrument and device. (interchangeability).
The benefits of the IVI standard to users are mainly reflected in the following four aspects:
1) Reduce the long-term maintenance costs of applications;
2) Reduce system downtime and ensure production is not affected;
3) Improve application reusability;
4) Improve programming efficiency and program speed.
5. Influence of virtual instruments on military test technology During the Cold War era, the most advanced ATE technology first served military purposes, and then gradually commercialized into civilian use. Since the end of the Cold War, major changes have taken place in the economy and science and technology, and the strategy of the US Department of Defense has also undergone changes. It is necessary to ensure the superior performance of weapons and equipment, and also to consider the affordability, that is, "do more with less." . For example, in order to achieve the goal of a single (set) device capable of accomplishing three maintenance and test tasks of Forward, Intermediate, and Depot at the same time, the US Department of Defense requires the three armed forces to widely use off-the-shelf commercial and general-purpose hardware and software products in order to realize the military automatic test system. Standardization and generalization. It can be seen that the development of military-civilian dual-use test technology has gone through a complete cycle - first applied to military technologies (such as VXI), further reduced in cost through commercial development, turned into advanced civil technologies, and finally sold to * use.
The research on the development trend of military ATE in the world shows that the integration of design verification, production inspection, diagnosis and maintenance, and standardization will become the basic requirements for military ATE, and the ATE established on the VXI and PXI bus standards will be the basic direction for future development. At the same time, the life expectancy of a military ATE system is generally 20 to 30 years. In many cases, the hardware of the instrument is not obsolete or needs to be updated. Therefore, there is also a need for a method that can improve the system with new instrument hardware without changing the program code - IVI. Military test software tools and standardization require huge investments, but as the technology is updated, these software and standards are expensive to maintain and very difficult to upgrade. IVI lays the foundation for establishing a bridge mechanism between military software testing specifications (such as ATLAS) and commercial technology tools.
1. Introduction Since the VI concept proposed by NI Corporation in 1986, now after more than ten years of development, not only the connotation of VI technology itself has been continuously enriched, the extension has been continuously expanded, and it has been widely used in military and civilian fields, and it has also been applied to modern monitoring and control. Technology has had a profound effect. For example, the original core idea of ​​the VI was to make use of the computer's powerful resources to software that would otherwise require hardware implementation in order to minimize system costs and enhance system functionality and flexibility. It is determined by the characteristics of the IT industry that the VI technology must also take the standardization and openness of this technical route. At present, VI has developed into an open technology with four standard architectures: GPIB, PC-DAQ, VXI, and PXI. In 1998, NI released the concept of Virtual Hardware and Interchangeable Virtual Instruments. Products designed according to the VH concept were already available, such as (NI5911, NI5912), and the IVI Foundation was established in 1998. It was formally established in the United States in August and published the corresponding IVI technical specifications. The application program developed based on IVI technology is completely independent of the hardware, improves the reusability of the program code, greatly reduces the maintenance cost of the application system, and is bound to become one of the main basic technologies of the measurement and control technology.
As for the extension of the VI, since the VI technology itself uses a computer as a platform and has convenient and flexible connectivity, it widely supports various industrial bus standards such as CAN, DeviceNet, FieldBus, PROFIBUS, etc. Industrial distributed I/O (Distributed I/O) products are on the market. Although Internet technology did not initially consider how to connect embedded smart devices together, companies such as NI have developed products that use a Web browser to view these embedded devices so that people can operate instruments and devices through the Internet to form home-based devices. Distributed measurement and control networks in offices and industrial sites. Moreover, standards related to MCN (Measurement and Control Networks) are actively being implemented and some progress has been made. With the further networking of measurement and control processes, a truly virtualized monitoring and control era is approaching.
2. The idea of ​​virtual hardware virtual hardware (VH) originates from the programmable device, which enables the user to easily change the function or performance parameter of the hardware through the program, thereby relying on the flexibility of the hardware device to enhance its applicability and flexibility. For example, NI5911/5912 is a high-speed (100MS/s), high-precision (8-21-bit), and flexible data acquisition device designed according to this idea, and its sampling rate and accuracy are variable. Since the general ADC is a user variable sampling rate, the following introduces the flexible resolution technology used in the NI5911/5912.
The so-called flexible precision technology consists of a specialized digital filter, high-speed ADCs, DACs, and DSPs for decimation and linearization (as shown in Figure 1). For 4 to 100 MHz bandwidth signals, the system can use a conventional method to operate at a real-time sampling rate of 100 MS/s with 8-bit accuracy. When the bandwidth of the measured signal is below 4 MHz, flexible precision can be used to achieve effective vertical accuracy. Achieve 21-bit. In the flexible precision mode, the wide-band quantization noise in the sampled signal is filtered out by the noise forming circuit, then the data is sent to the DSP for linearization, and the anti-aliasing filter in the DSP is further used to filter out the high-frequency noise and finally extracted. The technology reconstructs the waveform at a lower rate, resulting in an effective vertical accuracy of 8 to 21 bits. It should be pointed out that all signal processing is done in real time on the 100 MHz data stream. This ensures that no data will be lost during the acquisition and processing.
Figure 1 NI5911/5912 block diagram
3. Graphical and Zero Programming Development Environment The rapid update of the VI system and the online update of its testing process are forming trends in the world. The standardization and serialization of instrument buses has created good hardware conditions for the rapid formation of ATE systems. Another aspect of the problem is how to implement rapid on-line programming of test software to meet the ever-changing test requirements. The graphical and zero programming development environment was born to meet this demand.
3.1 Architecture of the Graphical Development Environment The graphical development environment, also known as the G development environment or the G language (Graphical Language), is increasingly familiar and used by more and more test engineers. The following uses NI LabVIEW as an example to introduce the architecture of the graphical development environment.
As shown in Figure 2, a complete G development environment (Full Development System) consists of two parts, BasePackage and ExtensionPackage. The engine part is the core of the entire graphical development environment. It includes edit modules, run modules, and debug modules.
Figure 2 Architecture of the Graphical Development Environment
The LabVIEW development environment is divided into a front panel (frontpanel) and a flowchart (blockdiagram). The former is a graphical user interface (GUI) for human-computer interaction, and integrates user input (control) objects such as knobs and switches; It is the graphical source code of the program. It includes functions, structures, terminals on the front panel and display objects, and connections. The function of the editing module is used for programming the front panel and the flow chart, and the graphical element library is used to edit and debug the tools of the front panel and the object on the flow chart. The functions and functional modules used in the control and display objects and flowcharts used in the front panel (such as arithmetic operations, instrument I/O, file I/O, and data acquisition operations) and the running modules are the engines of the programs. The debug module includes "highlight execution", "set breakpoint", "probe", and "single step" debugging tools, the most distinctive of which are "highlight execution" and "probe". "Probe" is used to display the value of a variable online while the program is running, and "execution highlighting" is used to track the flow of data during program execution. The instrument interface module includes VISA library, GPIB library, serial port library, DAQ library and VXI library. The programs in the Instrument Driver Library are application source code provided by NI and its system alliance members or hardware vendors to control a specific instrument to simplify the application engineer's program development process. The advanced analysis library is used to increase the program's data processing capabilities, including signal generation, DSP, measurement, digital filtering, windowing, curve fitting, probability and statistics, linear algebra, matrix operations, and various additional numerical methods.
3.2 Architecture of a Zero Programming Development Environment The G development environment utilizes terms, icons, and concepts familiar to scientists and engineers and uses graphical symbols rather than textual instruction codes to describe the behavior of the program. Therefore, it provides people with the means to implement the instrument. Easy way of programming and data acquisition system. Even so, in the field of industrial automation, there are open standards such as OPC (OLR for Process Control) and Foundation FieldBus, and application engineers need to develop human-machine interface (MMI) or supervisory control and data acquisition (SCADA) with many common features. In order to shorten the program development cycle and improve program quality, National Instruments introduced BridgeVIEW, a software development environment that combines G development environment features and zero programming features.
Figure 3 BridgeVIEW architecture
As shown in Figure 3, BridgeVIEW is a client-server architecture consisting of three parts: MMI/SCADA, Engine, and Device Server. MMI/SCADA is a user-developed application that includes GUIs, monitoring programs, data analysis and visualization, and process real-time control. The development of MMI/SCADA can be done either with the previously described G language or with so-called Tag tags. Configure tag properties such as I/O points, parameters, history data records, and alarm events that you need to access by tagging and programming without programming. The application exchanges data by sharing the real-time database with the engine. The device server collects tag values ​​and status information in real time and passes them to the engine. It should be noted that the application, engine, and device server operate separately in BridgeVIEW and therefore can achieve high operating speeds.
4. Interchangeable virtual instruments If you change the operating system or instrument hardware for years, you must revisit the test program. Although cross-platform development environments such as LabVIEW and LabWindows/CVI as described in the previous section ensure that changing the operating system does not require modification of the test program, the replacement of hardware devices (such as changing HP's DMM to Fluke's DMM) requires modification of the test program. This problem is caused by the lack of uniform standards among device drivers of different hardware vendors. The purpose of the IVI Foundation is to develop new instrument programming standards so that applications are completely independent of hardware devices.
The core of the IVI specification is the IVI device driver library. The library divides the drivers for all devices into five categories of oscilloscopes, multimeters, signal sources, switches, and power supplies. It defines a standard programming interface for communicating with each type of instrument. It is impossible for all instruments in each class to have exactly the same function or capability. Therefore, it is unrealistic to specify a unique standard interface to ensure that all instruments in the same category can work properly. The IVI specification divides each type of instrument driver into basic capabilities (fundamental capabilitices) and extensions (extensions). The former defines the capabilities and attributes common to more than 95% of the instruments in the same instrument; the latter defines many of the special features and attributes of each instrument.
The standard instrument class driver works in a "virtual" way. For example, the application calls IviDmm-Configure instead of calling FL45-configure or HP34401-Configure directly. In this way, when the system is using the FL45DMM, the program will be automatically loaded into FL45-Configure dynamically during operation. If you later replace the FL45DMM in your test system with the HP34401DMM, the IviDMM driver automatically directs you to call HP34401-Configure. According to this "virtual" approach (as shown in Figure 4), the differences in the characteristics of different instruments in the same type of instrument are "shielded" to ensure that the application program is completely independent of the hardware device, that is, to ensure the interchangeability of the instrument and device. (interchangeability).
Figure 4 IVI class driver ensures the replacement of instrument equipment in the system without modification of the program
The benefits of the IVI standard to users are mainly reflected in the following four aspects:
1) Reduce the long-term maintenance costs of applications;
2) Reduce system downtime and ensure production is not affected;
3) Improve application reusability;
4) Improve programming efficiency and program speed.
5. Influence of virtual instruments on military test technology During the Cold War era, the most advanced ATE technology first served military purposes, and then gradually commercialized into civilian use. Since the end of the Cold War, major changes have taken place in the economy and science and technology, and the strategy of the US Department of Defense has also undergone changes. It is necessary to ensure the superior performance of weapons and equipment, and also to consider the affordability, that is, "do more with less." . For example, in order to achieve the goal of a single (set) device capable of accomplishing three maintenance and test tasks of Forward, Intermediate, and Depot at the same time, the US Department of Defense requires the three armed forces to widely use off-the-shelf commercial and general-purpose hardware and software products in order to realize the military automatic test system. Standardization and generalization. It can be seen that the development of military-civilian dual-use test technology has gone through a complete cycle - first applied to military technologies (such as VXI), further reduced in cost through commercial development, turned into advanced civil technologies, and finally sold to * use.
The research on the development trend of military ATE in the world shows that the integration of design verification, production inspection, diagnosis and maintenance, and standardization will become the basic requirements for military ATE, and the ATE established on the VXI and PXI bus standards will be the basic direction for future development. At the same time, the life expectancy of a military ATE system is generally 20 to 30 years. In many cases, the hardware of the instrument is not obsolete or needs to be updated. Therefore, there is also a need for a method that can improve the system with new instrument hardware without changing the program code - IVI. Military test software tools and standardization require huge investments, but as the technology is updated, these software and standards are expensive to maintain and very difficult to upgrade. IVI lays the foundation for establishing a bridge mechanism between military software testing specifications (such as ATLAS) and commercial technology tools.
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