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Time Delay between two triangular signals

May 9, 2017, 9:03 am
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I will be having one triangular generated waveform, and after some time, I should receive the same signal but with some time delay (using USRP). Is there a way to find that time delay?

I have a very basic VI where I simulated the received signal by another signal generator but with a phase shift. 

I actually have another issue in the attached VI that the two signals do not appear together on the same chart although I suppose I did the right step by bundling them as I have read on the forum.

Thanks.

 

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Xbee API Frame - ADC Data decoder

May 9, 2017, 10:16 am
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Hello,
I am receiving data from the serial port from an XBEE and I want to take the portion 
corresponding to a value within the payload.
So far, I have extracted the portion and regenerated the numeric data with Type Cast.
But that data I only managed to indicate in U16.
My problem is that since I need to manipulate that data in a mathematical formula, I must
treat it as SGL and I do not know how to get it with Type Cast or something like that.
This result will be to show on a humidity and a temperature indicator. Below I leave a 
schematic where I get the plot and I get some data like the one I need.
For any question about what each byte in the Zigbee package means, I leave a link
(http://docs.digi.com/display/RFKitsCommon/Frame+structure). And My Diagram
Thank you all and have a great day.
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In-place overwriting of memory chunk by external libraries

May 9, 2017, 10:24 am
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I'm trying to understand some example code from the SDK of an instrument (a Picotech oscilloscope, link to SDK). If I look at one of the example routines, such as the snippet below, my immediate expectation is that the I16 array going into the inner loop would have its values update once per iteration of the outer loop and would stay constant while the inner loop executes. In fact, when you hook up the hardware and run it, the array updates every time the inner loop executes. 

 

What's going on is that those subVIs are essentially just wrappers around some calls to external routines linked in through DLLs, and the routine just before the inner loop (PS4000 Start Stream) sets up a fixed-size buffer (the I16 array) and the routine inside the inner loop (PS4000 Get Stream Values) does an in-place overwriting of some part of that chunk of memory associated with that buffer array, so that when the array subset command executes, it extracts the latest measurements from the buffer into a dedicated array for display or further processing.

 

My question is essentially what are the rules associated with this sort of thing? In my own code, I can just slavishly copy the structure of this example, but I'd prefer to understand exactly what are the constraints in terms of what can I do with that buffer array that won't break the behind-the-scenes updating and also if there's any straightforward way of telling that this is going on in general code (since it does essentially break the dataflow paradigm). What I've been doing in the early versions of my own code is to take each chunk as it's spat out by the Array Subset operation, stick it into a queue, and then use a separate consumer loop to dequeue and process as needed; so just treat the initial source of the data as a bit of a black box.  I'm nervous about using (or writing!) code that I don't fully understand, so that's not really ideal...

 

Thanks,

Daniel

 

picoscope snippet.png

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Error while trying to open VI: Failed to load dynamic library because of missing external symbols or dependencies

May 9, 2017, 10:25 am
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Hi all,

 

I have a labview project that was left behind by a former co-worker that I've been tasked with investigating. When I try to open his main VI, I get an error that the VI could not be opened due to missing dependencies in the dynamic library. I already updated a bunch of links to missing VIs in the lvproj file. As far as I can tell, the main VI was loading a bunch of functions from a LLB that I have unpacked and re-linked to, and I can open the VIs in the LLB.

 

Does anyone know a way to show which dynamic library (I'm assuming this is a .dll) is messed up?

 

Thanks

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Producer Consumer Loop Hanging

May 9, 2017, 11:10 am
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Hi everyone,

 

I am starting what I hoped would be a simple program.  I have a producer consumer loop with three events; Run, Load and Stop.  Within the Run event, I use the timeout of an event structure to time how long to wait between measurements.  I use to always use a wait/delay, but I would like to be able to interrupt the wait if I push stop.  

 

If I first push run in my code, it goes to the run event and if I push the load button it goes to that event, and if I push run again, it goes back to the run event.  Of course, when I push stop, it stops the program.

 

But if I push Load first, before any other button, it goes to the load event but gets stuck there.  I really can't see why and I was hoping someone could help me see what's going on.

 

Thank you!

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Capturing a subset of a string from Serial Port Read

May 9, 2017, 11:38 am
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Hi All

I have a device that spits out data at a serial port every 100ms. I am able to write to the device then need to read the serial port to ensure the changes took affect. The serial port output i need to capture looks something like this:

 

12345678

23456789

12345678

23456789

12345678

23456789

12345678

End of data

 

Due to poll speed of device, sometimes when I open a visa session and read bytes from the serial port I wont get the full set of data, or sometimes I get more than 1 full set of data. So, what I am doing is reading, matching string "End of data", then checking to make sure I have a minimum string length before "end of data" so I know I have captured all 7 lines of numbers I need. This is in a loop I repeat until successful. From there I am kind of stuck. Because I don't know where offset "0" is (it changes from capture to capture), I don't know how to trim out what I don't need and get my starting to point to be exactly at the first line of data. Its like I need to work backwards from "End of data". Any suggestions? Hopefully that makes sense and sorry but I cannot upload my current code. Thanks!

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.net constructor doesn't see all the objects

May 9, 2017, 12:08 pm
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I'm using LabVIEW 2013 and I'm trying to use a .net assembly to send command to our hardware through USB port. I couldn't following the path provided by software developer because I couldn't see all the object he sees. Any suggestion?  Thanks.

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Oscilloscope with Arduino and Labview

May 9, 2017, 12:31 pm
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Hey there,

I am currently working on an Arduino based Oscilloscope. The project is divided in two main parts:

1.) Measuring

For this I use an Arduino Uno and the "analogRead" command to read the values.Then I store the measured data and send it via "seriellPrint" via USB to my Computer.

2.) Data processing

In LabView I use the VISA-Interface to Read it. However, I have a problem: I have tried to store the received data in an array and convert it to an analog Signal. For storing the data in an 1D array I use a for-loop and it's iteration counter. But when I look into this array I see that only the last two slots of the array were used for data storing. The rest of the array is always empty.

Please can you tell me where my mistake is?

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LabVIEW frequency measurement via Arduino UNO analog pin

May 9, 2017, 1:40 pm
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Hi everybody,

I'm trying to realize a simple frequency measurement with Arduino Uno.

The connection between Arduino Uno and LabVIEW is ok, but the value of the measured frequency with LabVIEW is not correct.

You can see from the image that I'm generating a tone from the Arduino digital pin #8 with a frequency of 80Hz, but both the Tone Measurements and Spectral Measurements block gives me inconsistent results compared with  the input signal.

I tried to use different LabVIEW blocks but I had always the results.

I also tried different sampling frequencies and different number of samples.

Do someone know why? What can I do?

 

Thanks.

 

Problem1.png

 

 

 

Problem2.png

 

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Is HTTPS supported on LabVIEW RT?

May 9, 2017, 2:02 pm
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Hi,

 

Can anybody confirm they have used LabVIEW on a RT target to communicate using HTTPS?  If so, how do you do so?

 

Thanks

 

Ashley

 

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Error -200077 occurred at DAQ Assistant

May 9, 2017, 2:35 pm
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Hi,

 I am using NI 6211. I want to measure temperature from thermocouple.

When I use CJC Source-Built-in it gives me error. Without cjc source I am not able to measure accurate temperature. Need help if anybody knows let me know.

Thanks

Vipul

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Issue with tab controller

May 9, 2017, 2:59 pm
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Dear All,

 

I am trying to LabVIEW's tab control to switch between various control elements for a scientific instrument I am constructing. I set it up identically to the tab control in the NI example, which I can get to run fine on my computer. While I seem to have successfully gotten the structure setup and can get it to run one tab at a time (the one selected when I click on it), I cannot switch between tabs while the software is running. I have included a copy of my code in hopes that it will be of help in solving this problem. 

 

I tried an event structure (set to value change, with the "new val" tab connected to the tab selector) and it would run the second tab clicked on but no others, even though the structure was placed in a while loop set to never stop.

 

Any help you can provide would be greatly appreciated. Thanks! 

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Labview driver for Newport ESP301.

May 9, 2017, 8:37 pm
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Hi everyone,

I am trying to write a Labview program to control Newport Motion Controller ESP301. I found a file - ESP301_LabVIEW_Drivers_Manual and the page of National Instruments about Newport npesp301; but I cannot find the driver. And I cannot find the driver in Newport website either. Does anyone know where to find this driver? Thanks!

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After installing the tds 794d driver on labview 8.5, the palletes dont work and labview crashes.

May 9, 2017, 10:47 pm
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While loop

May 9, 2017, 10:51 pm
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Hi everyone,

 

I am working in a Labview project which has some structures, one of them is a while loop. In this loop I receive a numeric variable (4.25) and then subtract 0.25 until the result will be zero. The issue is that i've tried everything but still i can't do it. So your help will be greatly appreciated.

 

Thanks.

 

 

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Can't buil my installer--Labview2015

May 10, 2017, 12:52 am
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I can build exe.When i buil installer,the build was unsuccessful.The error message is "The following product(s) are not found on the system or have been upgraded".

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Exécuter une partie du programme une seul fois en fonction d'une commande

May 10, 2017, 1:02 am
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Bonjour à tous.

Dans le cadre d'un stage je suis amené à gérer un calibrateur avec Labview.

J'aimerais qu'une partie de mon programme s'exécute une seul fois en fonction d'une commande d'indice de ligne. Cette commande permet de choisir la chaine de caractères à envoyer provenant d'un tableau de chaines au calibrateur. Le problème que je rencontre actuellement est que cette chaine est envoyée en continue sur l'appareil. Tout mon programme est dans une boucle While.

Comment pourrai je régler ce problème?

Merci par avance.

 

 

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NI platform to Choose

May 10, 2017, 1:13 am
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Hi,

 

We have to develop a system which continuously monitors the alarm status and display in the UI. Currently these alarms are physical Bulbs and we want to move to More intuitive visualization with LabVIEW. Additionally we want to have data acquisition of some of the parameters like pressure, flow etc ( and possibly some analytics )and also have them displayed in HMI ( touch screen monitor). And have detailed floor plan kind of UI showing all the alarms.

 

Would building a system around C-Daq windows controller chassis with touch screen monitor suffice for these requirements, note that this system would have to run continuously for Months (years) as these are safety critical alarms.

 

Please let me know what is the correct NI platform to do this.

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can't see instruments as a visa resorce in labview

May 10, 2017, 1:28 am
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Hi,

I am using a Keysight GPIB-USB 82357B with Labview. I followed the instruction how to configure the Keysight as a secondary VISA and it is working. I can see in my NI-MAX my instruments but when I look for them in a VISA resource control in Labview I can't find them.

pic1.png

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NI MAX crashing

May 10, 2017, 1:31 am
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Hello,

  I've been having problems with launching NI MAX. Right after launching MAX, I see the splash window with the description "Initializing...". Shortly after this, another window comes up with the following message

 

NI MAX has detected an unexpected internal warning. Visit ni.com/info and enter the info code MAXKnownException for more information.

 

In the details section of the window, I see the following:

 

The CniDMFuiProvider::Initialize plug-in caused an exception in the CmxExecutionThreadPool:Smiley Very HappyoWorkNonUI function in the MAX process.
See this file for details:
C:\ProgramData\National Instruments\MAX\Logs\MAX\cfa87bbc-9467-4a1e-8425-a0f989b583d2\c97ebd86-9085-4d7e-8a21-c959fb281b93.dmp

I have attached the "dmp" file that is mentioned above as well as the summary log file present in that location as well. As far as troubleshooting, I've done the following

 

- restarted computer to see if behavior persists

- used "msconfig" to disable everything I could except for needed microsoft services at computer startup

- went into control panel and tried to do a repair on NI MAX

- went to "ni.com/info" and looked at the MAXKnownException information that was listed. In particular, the error message shown above doesn't match any of the Exceptions listed in that table.

 

Any ideas on what my next step should be?

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