HELP! VI to record data for set time on button press

December 26, 2018, 12:41 pm

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I have been asked to develop a VI that can record ECG data to an array and output to TDMS. I am currently using a sine waveform to test the VI as our DAQ is not portable. I have put a VI together, but it has a whole bunch of problems. I have no labview experience, which makes this a lot more difficult than it probably should be. Attached is what I have so far. I have fiddled around with all different types of structures and loops within loops.

 

What I need is:

1. Live data display of about five seconds of data for each of the four channels (currently all showing the same sine waveform, but not five seconds worth. It looks like it displays like a half second of data.

2. Records variable (somewhere between 5-10 seconds) of data at around 1000 Hz (would be nice to be able to control this too) into four arrays and outputs them all to a TDMS file. Current output isn't the full 5 seconds, shows only one channel, and once the record button is pressed it just keeps spitting out files until you stop the vi manually. I tried putting in a "for" loop that runs once, but it ignores this and runs the same way.

 

I have attached one of my many VI attempts, as well as a sample of the output data.

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How do I change the read / write of local variables at once?

December 26, 2018, 4:53 pm

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Hello.

When only one local variable is selected, read / write changes are possible in the right-click menu.

However, after selecting several local variables, the read / write menu disappears from the right-click menu.

Is there a function or shortcut for changing read / write of several local variables at once?

My lab version is 2015 SP1.

Thank you.

NXG Web Module and Database

December 26, 2018, 8:47 pm

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Hi,

 

I am new to LV NXG and NXG web module. Is there any reference on how to access database (preferably NI citadel) from NXG web module?

 

Thanks,

Irfan

labview with access database

December 26, 2018, 11:16 pm

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Hi everyone:

I am using labview opc server collection data from 5 plcs then store into access then someone can query these data later.

Problem is i can not combine 5 plc`s data into one table,now 5 plc`s data in 5 different data table and all the data collecte are in 5 tables in access database

Does someone now how to put all the data in one table and all the queried data are in one table.

Best way to find fast and acurate duty cycle measuremeants?

December 27, 2018, 5:31 am

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I have a square wave signal being inputted. What I would like to do is find the duty cycle for each period throughout the signal, and not just the average duty cycle. Using the Read Pulse Duty Cycle and Frequency (Continious).vi it will measure the duty cycle exactly, but the VI is very slow. There will be a few thousand periods per signal, and that one takes a few seconds to calculate 100. I have also a software based approach for finding each duty cycle. This one is much faster, never measured the time but can calculate it all almost the second I say run. However, when running that VI the duty cycle values calculated are wrong. I'm wondering is there a way to pretty much combine both approaches, to get the speed of the software way, and the accuracy of the hardware?

Labview and STM32 microcontroller

December 27, 2018, 5:15 am

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Hi everyone,are there any one in group try to connect between labview and STM32?.If you did,please give me some intructions.Many thanks

Additional icon editor glyphs

December 27, 2018, 10:19 am

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Some couple years ago someone posted a link to a huge repository of glyphs that they used.  It wasn't LabVIEW specific but had a ton of good images.

 

I downloaded them and used them a lot, but I've got a new computer now and can't seem to find the post. So, does anyone have the link? (or perhaps a repository that they use)

File Explorer Sort

December 27, 2018, 11:09 am

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I would like to sort files and folders EXACTLY the way File Explorer does on Windows 10.

Gone through a number of example programs from the forum but they do not work exactly.

 

Apparently File Explorer calls a function called StrCmpLogicalW.

Is there a way I could call this function from LabVIEW?

 

Appreciate any suggestions on how this can be done with LabVIEW.

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Opening Two LabVIEW Applications at a Time

December 27, 2018, 1:41 pm

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Hello All,

I have created a LabVIEW project and have gone through all the steps to make it into an executable as well as an installer. Everything works and I am able to use my program. Just one thing; I can only have one open at a time. Like with other windows applications, it allows me to have several windows of the same application open (for example Google Chrome allows you to have many windows open at the same time). Is there a way that I can have two windows of the same LabVIEW created application open at the same time? Thanks!

Read binary file yields erroneous data after first correct 370 elements

December 27, 2018, 2:47 pm

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In LV 2014.1f11 (32-bit) I saved data of type SGL  to binary file. When i try to read the first 1492 elements back, ( saved many more than 1492 elements. But I when read the day back in, i found that the data after the first 370 elements were invalid (The rest read something like 2.33849E-41 all the way to the end) .i specified type SGL when reading in to ensure consistency with data type saved  Any ideas?

Ending Time Loop w/o Stopping LabView

December 27, 2018, 3:37 pm

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For starters, please bear with me. I'm extremely new to using LabView and its wiring. All I have learned so far has been self-taught by being thrown into a position at my current work given no one else could help the 2 other people here. I refrained as long as I could before resulting to pestering people on the forums who've been doing it for years, but there's only so much I could find on the internet for a program I've discovered that can do virtually anything. Consider this my intro lol.

 

Our Equipment (Probably Irrelevant).

Compact DAQ Chassis

NI 9209 Module

NI 9211 Module

 

What our VI Does.

Constantly displays temperatures and pressures during testing.

We just figured out how to keep LabView running without recording unnecessary data using the Case Structure (elementary I know lol).

 

What I want to do.

Record data for a specified length of time - and not ending LabView once done.

 

Less Important but maybe worthwhile Idea.

After data has been recorded for said time, start recording on a separate/identifiable file to note back on data if needed. (Possibly deals with the 'End Late?' if I understand correctly)

 

What I currently have the VI Doing.

LabView up and running, performing 'infinite' loops/iterations so we can see the current readings.

A Time Case that starts recording data for a specified time at the press of a button. But then completely stops the VI once completed.

 

Current VI Diagram

A quick, simple test VI I've been playing with.

I know this post is probably excessive but I'd rather be safe than sorry and provide as much details as I can.

Is there a simpler way? Am I going about it in a more necessary complicated way?

Any kind of help, suggestions, tips, tricks would be greatly appreciated.

 

Thanks again, 

 

PID gain scheduler table

December 27, 2018, 5:52 pm

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Hi everyone,

For my project, i am trying to build a lab View program to control temperature, pressure and vacuum in single zone and multiple zone furnaces and ovens especially for curing composite materials. I recently learned that PID auto-tuning is not accurate and might create unstable system. Thus, i am trying to implement PID gain schedule for the gain values. I was wondering what will be the best approach to fill gain values table for various temperature and pressure data. Thanks

Generate power spectrum using power spectrum and PSD vi

December 27, 2018, 9:52 pm

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Hi All,

I am using write from measurement vi to collect acceleration data and saved in text file. Then, I'd like to use read from measurement vi to plot the acceleration data and power spectrum. However, the power spectrum graph does not show any plot at all. Is there any problem with the code? See attached for the VI and the acceleration data text (converted to excel for easy to attach). On the other hand, I am not sure why there's a white linear line shown on the "waveform graph"

 

Thank you,

Drake

exponential time component

December 28, 2018, 12:41 am

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hi everyone:

I have a problem on implementing the following equation on labview (exp[j 2 pi F t ]), as we know that

 exp[j 2 pi F t ]=cos(2 pi F t) +j sin(2 pi F t), I have a problem on entering the parameter (t) to the EXP block on labview.

PXIe-6366 digital output and analog input

December 28, 2018, 2:33 am

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I have this query regarding PXIe-6366, multi function DAQ. It has 2 AO channels, 8 differential AI channels and 24 DIO. Now,

(i) In MatLAB I have generated a .mat file having 15000 samples of doubles.

(ii) And I have a separate digital to analog converter board that I wish to communicate with using DIO pins of the PXIe-6366.

Basically I want to transmit that .mat file to my digital to analog converter board using 19 DO pins on a clock frequency of 8 MHz. And then the using 4 DI pins I want to receive data from the converter board. Now I know that DIO pins are individually programmable. And it has 10 MHz DO clock frequency. But I can't seem to display the clock frequency mentioned. How to generate and use it? Is this whole setup feasible?

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Opening LabVIEW 2017 block diagram

December 28, 2018, 4:57 am

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I had created a Labview file during my studies using my university computer with LabVIEW 2017. Now after a complete year I wanna review those files but sadly in my PC I am using LabVIEW 2013.

 

Online I have tried to search for a software using which I could view the block diagram but no luck.

 

If I upload the program could someone using LabVIEW 2017 upload the snippets of the block diagram?

Micro-Epsilon laser scanner on Linux RT

December 28, 2018, 4:25 am

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We use the ScanCONTROL 2910-xx laser profile scanner from Micro-Epsilon.They offer a LabVIEW driver for the Windovs platform and it works well.However, we want to develop the final application for the IC-3173 (Linux RT).Since communication with the sensor is carried out through the LTT.dll library, of course it does not work on the Linux platform.

There is also a Linux SDK (https://www.micro-epsilon.com/2D_3D/laser-scanner/Software/downloads/?dl=32).Is there any idea how to integrate the Linux library successfully into the LabVIEW program?
Another posible solution: Does Linux RT allow the installation of a third-party application, which would, for example, capture the profile and transfer it to a LabVIEW RT layer via the standard interface?

Opening LabVIEW 2017 block diagram

December 28, 2018, 4:57 am

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Moved to another board

Representing data on XY graph (timing)

December 28, 2018, 7:58 am

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Hello I'm new to LabVIEW.

 

I have a problem on timming my data. My profesor ask me to send data throught the serial port every 10 ms (from the Arduino, sending data from an analogic input and its respective sampling time), this part is solved, and I have to represent it in the xy graph every 0.5 seconds. So I have made a program wich reads the data from the serial port every 10 ms, it splits the array that I am sending (data, time) and it represents it in the graph every 10 ms. If I want to represent it every 0.5 seconds how can I do it? Also in some cases the LabVIEW shows an error in the VISA write and sends me wrong data, do you know why this happens? So if you see any error or know something that I am doing wrong tell me. Thank you all.

 

This is my LabVIEW program: When i press the button the LabVIEW send me '1' throught the serial port to Arduino and then I start sending data to the LabVIEW

And there is the graphic with errors every x time. 

Error in the VISA Write

This is the data that I am sending from arduino. As you see there is the sample time, every 10 ms and the lecture from the analogic input, left to right respectively.

 

 

label and track particles--Real time

December 28, 2018, 9:07 am

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Hi,

1.Background

    I'm working on an optical tweezer project which I would like to control and pattern the particles (1-2 μm) under microscope with the help of CCD camera.

2.What I have already done

    (1) I can detect the particles and their pixel positions by transferring the real-time CCD camera info into binary one

    (2) I can make the stage move to one particle (unlabelled) automatically

    (3) The laser on and off is also automated.

    (4) If in the region detected CDD camera, there is only two particles, my VI could move the one particle to the other one to make a very basic assembly automatically

3. What's my problem

   But, actually, I would like to pattern the arbitrary number of particles. Right now, the solution I could bring up is to label all the particles first, and then use laser to move each particle to the design position. Briefly speaking, I choose a region first, and the ccd camera detect their N particles. I would like to label them first, and then tell particle 1 to position 1, particle 2 to position 2 and so on. 

   The key problem is that I need to move the stage to let the particles at the center of the stage first, then i could open the laser to move it. Once I move the stage, all the particles position will mess up. What make things worse is that there might be new particles exist under CCD camera when the stage move. 

   So, is there any method that I could label the particles first even I move the stage (like give them an ID card)? or if you could offer another clue to make the pattern more easier rather than label them? Thanks.

 

Tip:  all the particles I use right now almost have the same size and shape, i.e. identical in a way.