The Design of Data Acquisition Signal Generator Based on LabVIEW
Wang Ju 1, a, Yun Lian peng2,b and Ding Rui3,c
1 College of Electronic and Information Engineering, Changchun University, China
2 Qi Ming Information Technology Co. Ltd, China
- College of Electronic and Information Engineering, Changchun University, China a youyou8221@yahoo.com.cn, bgpsylp_qm@faw.com.cn, c64865635@qq.com
Keywords: LabVIEW; Data acquisition; Signal generating; NI-DAQmx
Abstract. In this paper, we proposed a set of data acquisition signal generator based on LabVIEW development tools, and realized the data communication from data collection terminal to testing the PC that based on serial port. Completed the function which of including data acquisition, signal generating and verified by simulation. The different between traditional generator and the Labview designed generator is to banish tedious and bulkiness of the traditional generator. With its unrivaled hardware integration and other unparalleled features, LabVIEW is an industry-leading software platform.
Introduction
With the further development of computer technology and intelligent instrumentation, data acquisition and processing technology as one of the preparatory work of the digital signal processing, are widely used in military, industrial, communications, consumer electronics, medical monitoring and control areas. However, the field of measurement and control in today facing increasingly more and more strong challenges, the use of virtual instrument user software can greatly shorten the development cycle, increase program reusability. LabVIEW is powerful system design software built specifically for tasks performed by engineers and scientists. It is one software tool that can span all of your hardware components. Drivers are readily available for common hardware devices. Each hardware driver shares a similar, familiar programming model, and examples of how to use the model install directly into LabVIEW. It is a new type of computer equipment system which U.S. NI company development and manufacturing [1]. LabVIEW as the first establish virtual instrument graphical programming system which by means of the virtual panel user interface and block diagram, it is widely accepted by industry, academia and research laboratories as a standard data collection instruments and instrument control software.
The design of whole system
In this design, signal generation using LabVIEW internal signal occurred function library to realize, to obtain a discrete time series signal by taking the function value with equal time intervals. The part of Data acquisition take use of the PXI-6251 DAQ acquisition board, using the Acquisition sub-templates in LabVIEW. Because of LabVIEW offers a variety of graphics drivers, the users do not need to be familiar with the PCI computer bus can drive the above a variety of bus I / O interface equipment, and realize the data acquisition.
The hardware design of system
NI has introduced the NI-DAQmx driver software, by means of multi-threaded, intelligent synchronization and other new technology, its performance is greatly improved, meanwhile, reference to the polymorphic VI mechanism, make the programming interface become simple and efficient, the introduction of the DAQ assistant also greatly reduces the difficulty of developing[2]. The data collection in this paper selects the PXI-6251. The National Instruments PXI-6251 is a high-speed multifunction M Series data acquisition (DAQ) board optimized for superior accuracy at fast sampling rates. The real PXI as figure 1 shows.
Figure 1. PXI-6251
The first open “Measurement amp; Automation”, select the NI-PXI-6251 “DEV1” in “my system”, then click the right mouse button pop-up the window, select the PXI-6251 tube angle. View the graph of the PXI-6251 tube angle. As the figure 2 shows.
After found the graph of the PXI-6251 tube angle, Selected the appropriate tube angle. The details of the PXI-6251 tube angle as the figure 3 shows.
Figure 2. The path of tube angle to find
Figure 3. The PXI-6251 tube angle
The software design of system
The software design of this system is the core of the entire data acquisition system, is also the main component of the system. The software designed of the system use design ideas which modular and hierarchical. This hierarchical modular structure of the program will not only increase the maintainability of the program, but also increase the readability of the program, but also avoid a lot of repeat programming [3]. This system consists of the following modules: Signal acquisition module and signal generating module.
The design of Signal acquisition module
In signal acquisition hardware using the PXI-6251 DAQ board, in the software, we use the data acquisition module in LabVIEW. As figure 4 shows.
Figure 4. The data acquisition module
In LabVIEW data acquisition module, data acquisition is divided into a limited sampling [4], as the figure 5 shows. Limited sampling including the use of the limited sampling of the external clock. It should be needed attention that the sample rate and the external clock frequency should be set uniformly, because the time interval among adjacent data points by set is based on the frequency of the sample rate[5].
Figure 5. Limited sampling of the external clock
The design of Signal generating module
The design of signal generating is divided into the the front panel design and the back panel design, the back panel design that is software design. The module can generate the sig
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基于LabVIEW的数据采集信号发生器的设计
王菊、云连鹏、丁瑞
中国长春大学电子信息工程学院
中国齐鸣信息技术有限公司
关键词:虚拟仪器;数据采集;信号产生;NI-DAQmx
摘要：本文提出了一种基于LabVIEW开发工具的数据采集信号发生器，实现了数据采集终端的数据通信，对基于串口的PC进行了测试。完成了包括数据采集、信号生成、仿真验证等功能。传统的发电机和LabVIEW设计的发电机的不同之处在于消除了传统发电机的繁琐和笨重。LabVIEW拥有无与伦比的硬件集成和其他无与伦比的功能，是业界领先的软件平台。
引言：随着计算机技术和智能仪表的进一步发展，数据采集和处理技术作为数字信号处理的一项准备工作，广泛应用于军事、工业、通信、消费电子、医疗监测和控制领域。然而，当今的测量和控制领域面临着越来越多的挑战，使用虚拟仪器用户软件可以大大缩短开发周期，提高程序的可重用性。LabVIEW是一个强大的系统设计软件，专门为工程师和科学家的任务而设计。它是一个可以跨越所有硬件组件的软件工具。对于常见的硬件设备，驱动程序是很容易得到的。每个硬件驱动程序共享一个类似的、熟悉的编程模型，以及如何将模型直接安装到LabVIEW中。它是美国NI公司开发和制造的新型计算机设备系统[1]。LabVIEW作为第一个通过虚拟面板用户界面和框图建立的虚拟仪器图形化编程系统，被业界、学术界和研究实验室广泛接受为标准的数据采集仪器和仪器控制软件。
系统设计
在本设计中，利用LabVIEW内信号产生的信号产生函数库实现，通过具有相同时间间隔的函数值来获得离散时间序列信号。数据采集部分采用了PXI-6251 DAQ采集板，使用LabVIEW中的采集子模板。由于LabVIEW提供了多种图形驱动，用户不需要熟悉PCI计算机总线就可以驱动以上各种总线I / O接口设备，实现数据采集。
系统的硬件设计
NI引入了NI- daqmx驱动软件，通过多线程、智能同步等新技术，其性能大大提高，同时参考多态VI机制，使编程界面变得简单高效，DAQ助手的引入也大大降低了开发难度[2]。本文的数据采集选择了PXI-6251。国家仪器PXI-6251是一种高速多功能M系列数据采集(DAQ)板，对快速采样率的精度进行了优化。真正的PXI如图1所示。
图 1. PXI-6251
第一个打开的“测量与自动化”，在“我的系统”中选择nipxi -6251“DEV1”，然后点击鼠标右键弹出窗口，选择PXI-6251管角。查看PXI-6251管角的曲线图。如图2所示。
图 2. 管角的路径
在发现PXI-6251管角曲线图后，选择合适的管角。PXI-6251管角的细节如图3所示。
图 3. PXI-6251管角
系统软件设计
该系统的软件设计是整个数据采集系统的核心，也是系统的主要组成部分。系统设计的软件采用模块化和层次化的设计思想。该程序的分层模块化结构不仅提高了程序的可维护性，而且提高了程序的可读性，同时也避免了大量的重复编程[3]。该系统由信号采集模块和信号生成模块组成。
信号采集模块的设计
在信号采集硬件中使用PXI-6251 DAQ板，在软件中，我们使用LabVIEW中的数据采集模块。如图4所示。
图4.数据采集模块
在LabVIEW数据采集模块中，数据采集被划分为有限的采样[4]，如图5所示。有限抽样，包括使用有限的外部时钟采样。需要注意的是，采样率和外部时钟频率应该一致，因为相邻数据点之间的时间间隔是基于采样率的频率[5]。
图5.外部时钟的有限采样
信号生成模块的设计
信号产生的设计分为前面板设计和后面板设计，后面板设计是软件设计。模块可以使用公式描述生成信号,或几个传统常见的波形类型:例如谐波,方波,也都可以叠加在各种噪声的波形,例如:统一的白噪声,高斯白噪声,周期性随机噪声和几种常见类型的噪音。前面的面板设计如图6所示。后面板的设计，首先是为案例结构设计的，案例结构包括各种选择分支中的各种基本波形发生器。图7显示了信号发生器的前面板。
图 6. 信号发生器的前面板
图 7. 信号发生器后面板
系统测试
该系统首先在LabVIEW中收集正常信号，或通过PXI-6251 DAQ板进行用户编辑的公式信号，然后通过虚拟信号发生器在窗口中显示信号。它还可以通过前面板的按钮调节频率、振幅和相位。您还可以添加噪声，获取常规信号正弦波形。如图8。
图 8. 获取正弦波
总结
本文设计了一种基于LabVIEW的信号采集与信号生成功能的虚拟信号发生器。它可以实现信号的采集和信号的生成，以及频率、振幅和相位调整的功能。它可以生成几个常规信号或用户描述公式的信号。但是注意，用户要编辑的公式必须符合公式的书面格式。它也可以叠加在各种噪声上，然后提出一个完全虚拟的概念，使计算机进一步分析和处理。
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