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Introduction to LabVIEW-Three-Hour Course 2
dingxiubing 发表于 2008/10/8 15:43:11 679 查看 2 回复 [上一主题] [下一主题]
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这部分介绍VI最基本的两个组成部分：前面板和程序框图
The front panel is the user interface of the VI. You build the front panel with
controls and indicators, which are the interactive input and output terminals of the
VI, respectively. Controls are knobs, pushbuttons, dials, and other input devices.
Indicators are graphs, LEDs, and other displays. Controls simulate instrument input
devices and supply data to the block diagram of the VI. Indicators simulate
instrument output devices and display data the block diagram acquires or generates.
In this picture, the Power switch is a boolean control. A boolean contains either a
true or false value. The value is false until the switch is pressed. When the switch is
pressed, the value becomes true. The temperature history indicator is a waveform
graph. It displays multiple numbers. In this case, the graph will plot Deg F versus
Time (sec).
The front panel also contains a toolbar, whose functions we will discuss later.
The block diagram contains this graphical source code. Front panel objects appear
as terminals on the block diagram. Additionally, the block diagram contains
functions and structures from built-in LabVIEW VI libraries. Wires connect each of
the nodes on the block diagram, including control and indicator terminals, functions,
and structures.
In this block diagram, the subVI Temp calls the subroutine which retrieves a
temperature from a Data Acquisition (DAQ) board. This temperature is plotted
along with the running average temperature on the waveform graph Temperature
History. The Power switch is a boolean control on the Front Panel which will stop
execution of the While Loop. The While Loop also contains a Timing Function to
control how frequently the loop iterates.
LabVIEW 7.0 introduced a new type of subVI called Express VIs. These are
interactive VIs that have a configuration dialog box that allows the user to
customize the functionality of the Express VI. LabVIEW then generates a subVI
based on these settings.
Standard VIs are VIs (consisting of a front panel and a block diagram) that are used
within another VI.
Functions are the building blocks of all VIs. Functions do not have a front panel or a
block diagram.
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dingxiubing | 当前状态：在线
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dingxiubing 发表于 2008/10/6 14:30:36
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引用 dingxiubing 2008/10/6 14:30:36 发表于2楼的内容
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