Measure frequency with ni usb 6002

December 13, 2016, 3:42 pm

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I was wondering if it is possible to measure the frequency of a waveform signal with a ni usb 6002? I have been reading through the forums and looking for examples on how to measure the frequency, but haven't been able to figure it out. I have tried the tone measurement vi, the extract a tone from waveform function, fft power spectrum, and the spectral measurement vi, but I haven't been able to get any of them to read the frequency of my signal.

 

I am sampling continuous reading 1 sample at 10kHz and I am striking my force plate with a hammer to determine the natural frequency of the force plate. I am able to record the voltage of the waveform signal, but when I try to use the functions to read the frequency I get 0.

 

I have read about using the counter to measure the frequency, but I haven't had any sucess at that either...

 

Any help would be greatly appreciated! Thanks!

 

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Problem when simulating an 8051 MCU in Multisim?

December 13, 2016, 5:08 pm

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Hi,

I faced a problem when simulating a simple 8051 MCU circuit (blinking a LED)

The C-code is compiled successfully but when it is not linked.
Here is what is displayed in the result barre:

Multisim - Tuesday, December 13, 2016, 2:13:58 AM
--------------------------Building: Project: project1---------------------------
Note: -E compiler option was not present. This option has been added to the compiler build command temporarily.
Note: -O compiler option was not present. This option has been added to the compiler build command temporarily.
Warning: -G compiler option was not present. This option has been added to the compiler build command temporarily.
Warning: --ASMLIST compiler option was not present. This option has been added to the compiler build command temporarily.
Warning: -P compiler option was not present. The assembler files will not be preprocessed for #include directives.
Warning: The --ERRFORMAT compiler option was not present. This option has been added to the compiler build command temporarily.
Warning: The --WARNFORMAT compiler option was not present. This option has been added to the compiler build command temporarily.
Warning: The --MSGFORMAT compiler option was not present. This option has been added to the compiler build command temporarily.
Warning: -P compiler option was not present. The assembler files will not be preprocessed for #include directives.
Compiler results: 0 - Errors, 0 - Warnings
Linking...
Unable to find object file: D:\My Folder\Studies\Multisim\MCU Workspaces\MCU\project1\main_0.obj
Please help me!
thanks

 

Bringing value from 1 VI to another VI in the same Project file

December 13, 2016, 6:40 pm

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Hi,

 

I would like to bring a few value from the main VI to another VI under the same project file but I am not sure what is the best method of doing it. Is it by using global variable or by subvi? 

Thanks

End of file encountered on FormatIntoSting

December 13, 2016, 8:34 pm

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Running the attached VI gives me a popup with

  LabVIEW: End of file encountered.

  The top-level VI "crash.vi" was stopped at

  FormatIntoString on the block diagram of

  "crash.vi"

This is most likely a corrupted VI, but it's such a simple VI.

I did cut all the elements from a much larger VI, recreating the simple example from scratch doesn't seem to do it.

This is bit puzzling and wastes time to track down, as from a built executable the message was not clear at all.

ni usb 6210

December 14, 2016, 2:00 am

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Hello every one...

               Actually iam not understanding an specification regarding NI USB 6210 DAQ system i.e sampling rate 250 Ks/s means per single channel or same rate for multiple channels..iam going to use 4 analog inputs so each analog input channel can acces spped of 250 ks/s.....or it will devide according to no of channels

       Thank u to all....

Alternative for Queue in SubVI

December 14, 2016, 2:01 am

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Hello,

I'm currently searching for a way to eliminate the named Queue in my SubVI because it causes a memory leak. I want to save the data from my last SubVI call and use it when i call the VI again. The SubVI is also called multiple times in the main VI over a for loop with an array as input, It should remember to which array call which last data belongs. So the array element was the name in Obatin Queue which had the effect i am looking for, but this just works for a limited time because of the memory leak. Maye someone has an idea what i could try instead of the queue? Everything should happen in the SubVI when possible so i just have to pass the Array to the SubVI:

I already tried the feedback node in combination with reentrant execution, but this doesn't seem to work when the SubVI is called in the for loop because the old data from one array influence the next call of the SubVI.

 

I hope i described my problem accurate enough. Thanks in advance

Problem with program

December 14, 2016, 4:44 am

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Hello everyone,

 

I'm using the book graphical programming with labview and I am having a problem. I (think) I did the same as in the book. However, mine keeps saying that I am trying to connect two arrays with different dimensions. When I change the empty array constant attached to the for loop the program will run but it will not be the result it should be.

 

I included the labview vi. I'm hoping someone can help me out. 

 

Bart

 

 

Matrix of Charts - how?

December 14, 2016, 7:11 am

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Hello,

I want to create a 2D array of sweep charts. See attached photo of what I manually created using CTRL+C/CTRL+V.

I assume that placing the chart into an array will allow me to control their scale properties simultaneously and will allow me to easily choose the matrix's visible size (if I wanted to display 2x2 rather than 64x64 for example).

 

Background: I have an A/D which gathers 8 channels of data. The charts you see in the attached photo are displaying differential permutations of those 8 channels (channel1 - channel2, channel1-channel3... etc) - 28 in total.

When we will use 16 channels there will be quite a lot of charts. 

 

I am using LabView 2012 and unfortunately dragging a chart into an array doesn't do the trick. It simply doesn't work and I read about the fact that it's not supported. Not sure why though.

There must be a way to create such UI's in an elegant way.

 

I have considered using an array of clusters which contain a subpanel, but it became very messy and I failed to do it. Please tell me there is another, more elegant, way.

 

Help!

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Internal warnings after LabVIEW upgrade

December 14, 2016, 7:17 am

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I've just upgraded LabVIEW to version 16 and mass compiled and rebuilt a project previously developed with LV 2014.

As often happens after an upgrade of LV, the Internal Warning Reporter lists some warnings when I quit from LabVIEW. These warnings are listed every time I quit from LV after having worked on the project.

I send the report to NI (I did so many times in the past, but I haven't received any feedback from NI), but this behavior is quite annoying.

I wonder if there is a way to investigate these warnings and to detect if I should fix somehow my LV code or they come form a bug of LV.

Reset Time value after a time interval

December 14, 2016, 7:25 am

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Hi everyone,

 

Firstly, I'm sorry if my quesion is silly.

I just want to reset "Time" to 0 after a time interval like every 10 seconds. (Increase to 10 then reset to 0 and again)

How can I do it? Thanks to All

Memory leak XControl

December 14, 2016, 8:09 am

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Hi,

I am working on quite the big software project and just noticed a memory leak occuring. It is nothing big but fills up 4gb of ram in about 2 weeks which is unfortunate considering the software should run for months... I suspect the code of my xcontrols but can not find something wrong with it... Any help would be appreciated!

How to play multiple sound files simultaneously with no delay?

December 14, 2016, 8:12 am

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Hi there,

 

I'm working on a piano project, I'm using labview to play musical notes when a key is depressed.

 

I tried to use "Sound Output write", but it seems that this function is blocking, the sound card plays the next file only after the previous one ends. So if I depress many keys at the same time, sound files get stuck in sound card. 

 

I also tried to use "Play sound files", it isn't blocking, but when I depree the key, there's a tiny delay before playing. Pianoists from music department don't like this delay.

 

I'm wondering is there anyway I could solve blocking/delay problems? Which function shall I use?

Thank you in advance!

How do I generate a timed impulse from a boolean condition ?

December 14, 2016, 8:17 am

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Hi Everyone,

 

Background: I wrote a VI that generates an analog sine voltage on one output channel. I've offset the whole sine wave to go from 0-Vmax for every cycle. Any voltage in the second half of the wave cycle is forced to be the value of the baseline (which is equal to the amplitude input).

 

What I'm trying to accomplish now is to generate a 5V impulse on a second output channel at the start of each cycle in the sine wave. I've tried different methods, but they either give a signal too large in pulse width or unsynchronized with the sine wave. The boolean mentioned checked for an upward change in sine voltage (new cycle) to trigger a pulse as the VI is written now. The pulse should be around (0.1 sec, like the middle of an ECG pulse). What is the best method of completing this task?

 

Any help appreciated.

 

Help me create a 2D boolean control...

December 14, 2016, 9:01 am

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I want to create a 2D boolean control which sets or clears links between channels indicated in row and column headers, but I don't know how to create this.  I like the square LED as the boolean element for control, but I need text labels for the rows and columns.  If I create a 2D boolean array for the control, and two 1D string indicator arrays for the row and column text labels, then I need to make the sizes match so that they are aligned, but the string property: Size does not appear to be the same as the LED indicator property: Button Size.  Setting them identically results in misalignment.  What am I missing?

Error -2146827284 and Excel 2016 file extensions

December 14, 2016, 10:09 am

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About 3 days of Troubleshooting:

 

My LT26 EXE application created with LabVIEW 2013 started to generate a "can't find file error".

I found that it was most probably caused by an EXCEL upgrade to 2016 from 2013 which changed the excel template extension from .xlt to .xltx. I could duplicate this error by changing the file extension my app was looking for.

 

After upgrading to Windows 10 and monitoring Source Code operation, my LT26 application kept generating unknown error -2146827284 while executing LT26 Microsoft Office Toolkit Functions; specifically the subVIs containing the Excel Easy Text.vi function.

 

In my source code, I had noticed that I had noted when the code was first developed several years ago that I placed a note indicating: "Make sure a printer has been configured even though this computer may not ever be connected to a printer. The program requires a printer to be configured in order to generate the Excel report files." After configuring a printer, the application than ran normally. After removing the printer, the application still continued to function normally. Definitely not sure what was going on here and couldn’t duplicate.

 

I was now satisfied that everything was working at this point, however, the next day my application was generating the same -2146827284 unknown error again. I made a copy of the subVI containing all the Excel Final report functions and stored it to a SD card under the same name with a suffix -X. I then recreated the subVI containing the Excel Easy Text.vi functions in the original subVI containing the Excel Easy Text.VIs.  After recreating the subVI with functions from the LabVIEW 2016 palette everything now functioned normally with no errors. I could recreate the error by substituting the original subVI named with the -X suffix.

As I remember it, merely substituting the Excel Easy Text.Vis didn't resolve the issue.

 

Another issue arose with another application utilizing the Excel Easy Text.Vis. However merely replacing the Excel Easy Text.vis with identical functions from the 2016 LabVIEW pallette did not fix the issue. The interesting thing is that the application involved opening an Excel template which the Excel Easy Text Vis than performed their function on. If the Excel template was left open from the previous execution, the application would function normally, however, if the Excel template was closed upon application was executed the application would generate the "-2146827284 unknown error". In this instance recompiling the Microsoft Office Toolkit Directory: LabVIEW 2016>vi.lib>addons>_office remedied the issue.

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Adding tables on the front panel as FOR loop executes

December 14, 2016, 10:47 am

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Hi all

I have a VI that executes a FOR loop for four times. Lets say this loop A (i =4). Inside the loop A, there is another FOR loop which runs 20 times. lets say this loop B (i =20). When the B loop finishes (i.e., 0 to 19) it produces a table. I am using a local variable and shift registers to write this table. But I cannot have four tables (that should result after completion of the loop A) as a result on the front panel because i am using a local variable for the table. 

If anybody has suggestion so that I can have four tables as wanted, it will make my life easy.

Thank you all in advance.

 

Measuring Voltage for a Specific Command

December 14, 2016, 11:16 am

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I am using System Exec VI to launch CMD, which is able to measure the voltage and executing several commands at the same time. Currently I only want to get the voltage waveform for executing the last command from these several commands. However, the commands before the last command are supposed to set the environment for it. That is to say, I cannot run this last command only.

 

Could you please help me to figure out a way to measure the voltage for executing this last command only?

 

Thank you!

USB Serial Resource not found in LabVIEW

December 14, 2016, 11:45 am

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I am having an issue with a USB to serial power supply.  Windows device manager says it is present in the system but LabVIEW doesn't see it.  If I reboot the power supply it will normally fix the issue.  Any ideas why it can't be found in LabVIEW? I have tried refesh but no difference.

 

Matt

 

How to reset the DAQ Card through software

December 14, 2016, 1:41 pm

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Good afternoon,

 

We have an application developed in LabView 2012 SP1 and its compiled with DAQmx9.8.0 library pack. This software talks to a NI-DAQ6211 Card and reads data from it. The DAQ card is powered through its USB (and my HW guys tell me that there is no power input to the NiDaq Card).

 

In our specific application, one of the issues that we have is the power instability. If the input voltage to the DAQ fluctuates, it stops working and seems that it will not revive. The only way to get it workin is by Disconnecting and Reconnecting the USB cable (power cycling). In real world applications this is not a solution. Also, what we exected was that at least the card would reset itself it faces a power issue and resume working but it is not happening at all.

 

My question is that is there a way that we can send a "Reset" command to the NiDaq that will force it to do a soft reset?

(the HW guys are already working on stabilizing the power to the card)

Agilent PNA & LCA Driver with LabView 8.5

December 14, 2016, 1:51 pm

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Hi,

I'm working on remotely communication from PC to an Agilent PNA E-8361C and LCA (lightwave component analyzer) N4373C. I'd like to use LabView thru GPIB but cannot find the right command list. Could anyone help? I know this LCA is rarely used. Thanks in advance!