1、英文资料 Lab VIEW for Measurement and Data Analysis Lab VIEW is the tool of choice due to its unparalleled connectivity to instruments, powerful data acquisition capabilities, natural dataflow-based graphical programming interface, scalability, and overall function completeness. Introduction Users gener
2、ally start their work by acquiring data into an application or program, because their tasks typically require interaction with physical processes. In order to extract valuable information from that data, make decisions on the process, and obtain results, the data needs to be manipulated and analyzed
3、. Unfortunately, combining analysis with data acquisition and data presentation is not always a straightforward process. Application software packages typically address one component of the application, but seldom address all aspects and needs to get to a complete solution. LabVIEW was designed to a
4、ddress the requirements for a start-to-finish, fully-integrated solution, so that customers can seamlessly integrate all phases of their application in a single environment. Figure 1. Lab VIEW Virtual Instrument Block Diagram While there are many tools that independently address each of the requirem
5、ents, only Lab VIEW combines all of them with the power of graphical programming and state-of-the-art data acquisition hardware, using the power of your PC. It is the combination of data acquisition, data analysis, and presentation of results, that truly maximizes the power of Virtual Instrumentatio
6、n. A virtual instrument consists of an industry-standard computer or workstation equipped with powerful application software, cost-effective hardware such as plug-in boards, and driver software, which together perform the functions of traditional instruments. This is why applications and programs bu
7、ilt with Lab VIEW are referred to as VI (virtual instruments). As an engineering-focused tool, Lab VIEW makes hundreds of analysis functions available for researchers, scientists, and engineers, as well as students and professors. They can build these functions right into their applications to make
8、intelligent measurements and obtain results faster. Choosing the Correct Method for Analysis Users incorporate analysis into their applications and programs in different ways. There are certain considerations that help determine the way in which analysis should be performed. Inline vs. Offline analy
9、sis Inline analysis implies that the data is analyzed within the same application where it is acquired. This is generally the case when dealing with applications where decisions have to be made during run time and the results have direct consequences on the process, typically through the changing of
10、 parameters or executing of actions. This is typically the case in control applications. When dealing with inline analysis, it is important to consider the amount of data acquired and the particular analysis routines that are performed on that data. A proper balance must be found because they could
11、easily become computationally intensive and have an adverse effect on the performance of the application. Other examples for inline analysis are applications where the parameters of the measurement need to be adapted to the characteristics of the measured signal. One case is where one or more signal
12、s need to be logged, but these change very slowly except for sudden bursts of high-speed activity. In order to reduce the amount of data logged, the application would have to quickly recognize the need for a higher sampling rate, and reduce it when the burst is over. By measuring and analyzing certa
13、in aspects of the signals the application can adapt to the circumstances and enable the appropriate execution parameters. Although this is only one example, there are thousands of applications where a certain degree of intelligence - the ability to make decisions based on various conditions - and ad
14、aptability are required, which can only be provided by adding analysis algorithms to the application. Decisions based on acquired data are not always made in an automated manner. Very frequently, those involved with the process need to monitor the execution and determine whether it is performing as
15、expected or if one or more variables need to be adjusted. Although it is not uncommon for users to log data, extract it from a file or database and then analyze it offline to modify the process, many times the changes need to happen during run time. In these cases, the application must handle the da
16、ta coming from the process, and then manipulate, simplify, format, and present the data in a way that it is most useful to the user. Lab VIEW users can then take advantage of the many visualization objects to present that data in the most concise and useful manner. Lab VIEW offers analysis and mathe
17、matical routines that natively work together with data acquisition functions and display capabilities, so that they can be easily built into any application. In addition, Lab VIEW offers analysis routines for point-by-point execution； these routines are designed specifically to meet the needs of inl
18、ine analysis in real-time applications. Users should consider certain aspects when deciding whether point-by-point routines are appropriate. Point-by-point analysis is essential when dealing with control processes where high-speed, deterministic, point-by-point data acquisition is present. Any time
19、resources are dedicated to real-time data acquisition, point-by-point analysis becomes a necessity as acquisition rates and control loops are increased by orders of magnitude. The point-by-point approach simplifies the design, implementation, and testing process, because the flow of the application closely matches the natural flow of the real-world processes that the application is monitoring and controlling.
