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Questions tagged [labview]

LabVIEW stands for Laboratory Virtual Instrumentation Engineering Workbench and is a graphical programming system by National Instruments. The programming language is called G but often referred to as just LabVIEW.

LabVIEW is a graphical development environment offered as proprietary software by National Instruments and complementing their industrial controllers and data acquisition systems used in research labs and elsewhere.

The programming language itself is called G but usually referred to as just LabVIEW. The programming language is a parallel, dataflow, graphical, type-safe language. Dataflow provides automatic memory allocation/deallocation without the overhead of garbage collection. The language includes hooks to call into native C, .NET, COM, etc.

A LabView application is represented by a so-called "virtual instrument" or VI. A VI is divided into two parts: the front panel and the block diagram. The front panel acts as the GUI and defines the user interface where all the visual elements ("controls") are drawn and placed. Front panel controls include buttons, switches, knobs, and so on. Output elements like graphs, thermometers, and text boxes are also placed on the front panel.

The block diagram contains the execution code. LabVIEW code follows a dataflow-based execution paradigm. Functions are represented as individual blocks on the block diagram, with each function having zero or more inputs and one or more outputs. The dataflow programming paradigm dictates that a block (function) cannot execute until it has received data on all of its inputs, and a block outputs data on all of its outputs simultaneously once it has executed. Each block is, from the perspective of the block diagram in which it resides, atomic. Wiring determine execution order between blocks, and sections of a block diagram that share no connections can run completely in parallel.

To include LabVIEW code in your question, consider using a VI Snippet so that others can view, run and edit your code.

You can read more on the LabVIEW wiki or on the official National Instruments website.

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DAQmx Physical Channel variable to DAQmx Start Trigger source

I have LV application, where user can specify input and output channels for connected DAQ device. I want to synchronise both channels using trigger on the input channel, with analog output start as a trigger source (image on this site shows part of…
Soul Reaver
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How do you programmatically configure the Serial FIFO Receive and Transmit Buffers in Windows?

From Device Manager in Windows it is possible to configure the Receive Buffer and Transmit FIFO Buffer sizes for a serial port from Advanced Settings for a COM port: I would like to configure the values for the TX and RX FIFO buffers for COM ports…
rajsite
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Trying to implement an 8 point 1D DCT-II in labview; can only put one value in my output array

I am trying to implement a 1D DCT type II filter in Labview. The formula for this can be seen here As you can see xk = the sum of a sum function involving an iteration of n. As far as I know the nested for loop should handle the function with the…
mark mcmurray
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LabVIEW help explain simple Fibonacci sequence

I have an assignment due for my LabVIEW class that involves a Fibonacci sequence, here is the exact question: Create a VI that uses a WHILE loop to keep calculating iterations of a Fibonacci sequence until the ratio of |fib(n-1)/fib(n) -…
Umdoobby
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How do I configure DAQ assistant to generate voltage pulses defined by a waveform?

How do I feed the waveform pulses into DAQ Assistant to cause a DAQ 6259 board to generate desired voltage pulses? Using the Simulate Signal express VI I have created a square pulse waveform. My goal is to allow a LabView user to configure the…
user1068636
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Why does my waveform not have the right frequency intervals in labview?

In the LabView GUI I set the frequency to 300Hz = 1/300 seconds = 3.333 milliseconds and the pulse width to 2 milliseconds. This computes to a duty cycle of 60%. Why are intervals between the pulses shown below not equal to 3.333 milliseconds?…
user1068636
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Why are the pulse width and frequency of pulse not correct in my labview waveform?

In the following image you see I set the pulse frequency to 50 Hz and pulse width to 2ms. The duty cycle computes to 10%, which is fed into a signal simulator. When I execute the labview program the waveform I get is shown below: This waveform…
user1068636
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Concurrent multiple external executables and DAQ in LabVIEW

I am using LabVIEW 2009 with USB 6008 for DAQ from accelerometers. Besides, DAQ from the accelerometers, I have couple of other external executables which triggers the two different process (data write). By using System Exec.vi, I can trigger these…
PManjunatha
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Why does my waveform graph display pulses of width 3 ms when I specify them to be 2 ms in LabVIEW?

I am trying to generate pulse waves with a width of 2 milliseconds and frequency of approximately 100 Hz as shown below: According to this website: http://www.ni.com/white-paper/2991/en#toc1 under the section "Introduction to Pulse Width…
user1068636
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How do you modify a waveform graph in labview to display the time axis in milliseconds instead of seconds?

In the following LabView diagram: The waveform I get looks triangular, but I am expecting it to look more like square pulse waves. How can I change the time axis to display in milliseconds instead of seconds?
user1068636
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What is the most efficient way to quickly understand how a complex LabView VI works?

What is the best way to understand a complex LabView VI that controls a motor? My goal is to control the motor from a joystick. The wiring diagram shown below allows a LabView user to control the motor from the LabView GUI: move a slider up and…
user1068636
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Sometimes Windows Crash while LabVIEW operator Advantech PCI-1716 card

The system include 2 Advantech PCI-1716 card:http://www.advantech.com/products/PCI-1716/mod_86EC4C4D-F497-45C5-81DA-B8600C0EB36F.aspx I write a program with NI LabVIEW 7.1. The LabVIEW program can control the two PCI 1716 card. It work very…
summit677
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Build dll in student labview 2011

One method to build dlls from VIs is to right click the "build specification" in the project window -> new -> Shared Library (DLL). This has worked for me on other Labview installations, but not on my student edition. Is there an alternative/extra…
Davorak
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LabVIEW 2011 missing subvi

I am trying to load a .vi. While loading, LabVIEW is looking for a vi in ..\National Instruments\Labview 2011\examples\Vision Acquisition\NI-IMAQdx\High Level\SubVIs\ However, I do not have a "Vision Acquisition" folder in "examples". What am I…
LV3
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Subsequent events not triggering in while loop

I have a MAIN VI and a SUB VI which communicate events through control refnum. flow of events is as follows. 1) sub vi changes a value of its control and this event is handled in the main vi(this works). 2) main vi in response to the event changes…
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