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Modifying old VI for LabVIEW 2015

November 16, 2016, 3:19 pm
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Hi LabVIEW community,

              I am trying to modify an old VI to run on LV 2015. The old VI used “AI Update Channel.vi” and “AO Sample Channel.vi” for DAQ. I am trying to substitute them with DAQmx.

              My problem is that I can’t know exactly what the two old DAQ VIs’ function. The icons in Block Diagram become a question marks. I can understand some of the parameters that are connected to the question mark icon, from the captions and context help.

There are two parameters that I can’t understand their functions at all. One is a blue parameter called “I16 device”, which is probably has something to do with the for loop that included both sub-VIs. The description in the context help reads: “the device number you assigned to the plug-in DAQ board during configuration. This parameter defaults to 1”. This parameter is connected to both question marks. The other parameter is a pink string of 1. Context help shows that “No description available”. Each question mark has individual such parameter connected to it.

              The DAQ card we have is PCI-MIO-16XE-50. Only one AI (33) and one AO (21) is wired (the grounding for AI (66) is wired too). Hope that someone can provide me a hint for making new DAQ from DAQmx. Please find the program attached. Thanks!

 

Bo-Hong

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Reading Three Hall Effect Sensors Simultaneously

November 16, 2016, 5:37 pm
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Hi,

 

I am currently having problems with reading three hall effect sensors in simultaniously with Labveiw.  I am currently using a cDAQ chassis with a NI 9401 DIO card.  I am getting the error about resources being reserved.   I looked into error 201133 and I am unsure if it will solve my problem. In MAX I setup all of my tasks with different channels being used. I then set up the sequence suggested in the error 201133 help page and tried with all of the "DAQmx start tasks" in the first sequence block (shouldn't really do anything different but heck) and with the "DAQmx start tasks" in three seperate frames but neither worked.  I was wondering if anyone else has tried to hook up more than one hall effect or if someone would be able to explain better the error I am getting and how I can possibly solve it.  

 

Thanks. C.C. 

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Convert string into number and put the data in different array

November 16, 2016, 7:55 pm
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Hello,

 

I am a beginner of labview. The function I want to realize is very simple:

Reading data from serial port, if the first bit is 1, remove the first bit, put the data in array 1.

                                                if the first bit is not 1, remove the first bit, put the data in array 2.

 

However, when I run the VI, what happens is: if the first bit is 1, remove the first bit, put the data in array 1, put zero in array 2

                                                              if the first bit is not 1, remove the first bit, put the data in array 2, put zero in array 1.

And the data is like this. I think the problem is caused by the unwired tunnel in case structure, but I don't know how to solve it.

Could anyone give me some suggestions?

result.PNG

 

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Exception: Access violation (0xC0000005) at EIP=0x73A9B36A

November 17, 2016, 12:51 am
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Hi,

 

I am running into this error in a big plugin-based application, and it always occurs in one of the little subVI that has to reorder the waveforms in an array of waveforms.

 

The main application is a producer-consumer structure, and from the producer I queue 1 event each timeout that has to decodify data and append it at the end of the waveforms. Inside that, there is this little guy that gives the error. It occurs randomly, I cannot predict when or why. I have read 6 possible solutions to this problem on the forums, but none of them seemed to work on my vi. The one that made more sense to me was to avoid the use of "build array", but the results were the same.

 

Thank you in advance for your help.

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usb to serial communication

November 17, 2016, 12:48 am
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Hello everyone,

 

Im working on a project which has an device with rs232 port. I modified the basic Serial read-write VI. The program works fine with PC Serial port. But when I try to communicate with the same device through USB to serial converter (FTDI FT232RL FT232 USB TO TTL 5V 3.3V SERIAL ADAPTOR FOR ARDUINO BE0027) that's not happening and I get error message saying VISA read error. I searched forum for solution but still im at same problem.

 

pls help me out to solve with this problem.

 

Thanks.

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Labview processes randomly uses a lot of CPU (Ikads, Iktsrv & nidmsrv)

November 17, 2016, 12:56 am
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Hi.

 

I have Labview on my windows 10 pc, and sometimes totally random these 3 processes (Ikads, Iktsrv & nidmsrv) uses 20% cpu power each and i'm not even using labview. 

 

Why are they doing this ? how can i solve this problem permanently.

 

Best regards.

Henrik Andersen

 

 

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3D plot - Stewart platform

November 17, 2016, 1:31 am
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Hi,

I want to make 3D plot to Stewart platform (like on the left side on the picture 1.

 

I made a program which display points on 3D plot (picture 3), but I also need :

1. connect with lines points which form the bottom and top platform,

2. connect with lines 6 actuators in points on the platforms. Top platform should change position when i change the lenghts of actuators.

 

I checked many examples, but i couldn't find anything what i need, so I'm writing here to ask you about it.

 

 

 

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Convert Hex string to number

November 17, 2016, 1:35 am
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Hello,

 

I have a hexa string coming from a VISA serial communication which give me FFFFF756 but when I convert it to a decimal I got 4294965078. I used Hexadecimal string to number function.

 

How do you do to obtain a signed result ? Sometimes the hexa is positive and the other times it negative (in this case).

 

Thank you, Best regards.

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FPGA based FFT analysis - array?

November 17, 2016, 1:40 am
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hi

How can I analyze the spectrum given by the FPGA-based FFT, within the FPGA?

The "analysis" here can be for example to calculate the integral of the spectrum in a given window of frequencies (a sort of lock-in).

I can do it in the host, using a FIFO for the transfer and analyzing the array (of 8132 points) which comes out of the FIFO in the host. But is the same possible in the FPGA? Can I put the output of the FFT into an array and analyze it without leaving the FPGA? Or should I follow a different strategy?

 

The project requires to calculate the spectrum of an input signal, to analyze it, to feed a PID with the result of this analysys, and to send an output signal from the PID. Therefore speed is important and all should live in the FPGA.

 

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DC and AC at same time

November 17, 2016, 1:53 am
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Hi all,

 

I use a PXI-6723 and I want to generate two different signals.

AO0:1 with a DC signal

AO1:2 with a rectangle signal

 

The basic program I used is attached.

I tried it, but I get an error message. How can I solve the problem. I used another postage to solve the problem. But that doesn't work.

http://forums.ni.com/t5/LabVIEW/2-channel-sine-wave-generation-and-2-channel-dc-voltage/td-p/149079

 

In a first try I made the DC as a wave form with an offset. But that is not a good solution, because after the task is stopped, the signal should go to zero.

 

Thanks for help.

 

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several LAN Devices are not partially seen trough windows

November 17, 2016, 3:21 am
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to control several instruments (powersupply, nwa, dmm), we have a second lan-card in our testsystem control computer. sometimes after the start of our testsoftware, several lan devices are not seen through windows (win7). the viOpen fails, and you even not able to ping the device. the arp-entries are ok. the problem can be solved by flushing the arp-cache via cmd line argument "arp -d". the problem with deleting the arp-cache is that de running user is not a admin, so this cant be automated by the testsoftware

 

any guys here with the same problem ?

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Write data with date format into TDMS

November 17, 2016, 8:18 am
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Hello,

I'm trying to save data into TDMS.  I wonder if it is possible to configure a channel with only date format instead of date/time format. When I take a look the values through TDMS viewer, something like this is shown: "09/09/2016 00:00:00" rather than "09/09/2016". Also, when I click on Analog values to see the graph, the X-axis is not correct.

I suppose I missing something.

 

Thank you

Vicen

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Is there a way to enforce that a control is reloaded from default when a vi is run

November 17, 2016, 9:10 am
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I am trying to use what LabVIEW calls "type def" as a "configuration settings store".  I hope that I am not using it in a manner inconsistent with labelling, and I think that I am not doing that because it is a version of "control".  If I'm wrong here, pleases let me know the LabVIEW or ni best practice there. 

 

My question:

I have a case structure with two cases, and in each case is a copy of the same VI that reads from a different type-def control.  Will it associate the case-specific control settings with the case when it inputs into the VI, or does the vi have instance-to-instance memory? 

 

I'm hoping that it is case specific. 

 

My approach: I made the attached, and the zero-sum at the output leads me to think that each case retains the values of the type-def.

 

When I:

  • update the type-def ( close LabVIEW, then restart it and open the ctl files, and change the value and the default, then save it, and close LabVIEW again)
  • then run the vi (open vi and hit run)

then result is that it behaves as I think it should.

 

I would like to confirm that I am not kidding myself on how vi and type-def interact in the presence of multiple type-defs going into multiple instances of the same vi.

 

Additional question: does the execution re-entrancy impact this? 

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My stop button is not working

November 17, 2016, 9:16 am
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I have this Vi with two while loops. The stop button of the inner loop is working perfectly. When I press it, it get out of the loop. Then, If I press the other stop button of the bigger while loop, it does not work. Any ideas about why this happens?

 

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Screenshot Tektronix MSO4034 to PC using USB A-B Interface with No Scope Storage

November 17, 2016, 9:45 am
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This could just be a flat out "can't be done" type of question, but I've been working with GPIB and scopes with internal storage so far, so I had to ask.

 

Is there a way to take a screenshot with the default save location as the host device (your PC)? The MSO4034 we're using lacks storage, and I'm wondering if there is a way to bypass saving to the scope first, and just have it save straight to the connected PC.

 

Here is the VI I've used for the other scopes in our lab, as reference to how I've been doing this so far.

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where to save MD5 checksum

November 17, 2016, 9:45 am
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In order to prevent manual changes to certain ini files on my test system, I currently store an MD5 checksum of the file to another file. This is a bit mess: two files for the price of one! I was thinking I could store the MD5 hash of the (text) file contents to the metadata of the file, but I don't know how to do this in LabVIEW. Perhaps there is a better solution. Thoughts?

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TTL triggering tdms AI Data Acquisition

November 17, 2016, 10:52 am
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Hi,

 

Currently as a part of my research work, I am trying to acquire data in a .tdms file from an analogue channel triggered synchronously by each rising edge of a TTL signal input by a signal generator to PFI0. So to be clear, I won't be having any reference of time. Data will be sampled each time a rising edge of the TTL signal is input. Therefore the sampling frequency would ultimately be determined by the frequency of the TTL signal I input by the signal generator.

 

Initially I was trying to begin from some examples available, however no luck so far. I hope you guys can help.

 

Thanks in Advance,

Carl

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Displaying large data sets

November 17, 2016, 11:11 am
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Hello Everyone,

 

I am having some difficulty with managing and displaying large data sets for post testing review.  Attached is my .vi, it seems that it is getting hung up at the for loop trying to decimate the arrays so I am not trying to display 22k points of data on a 1k wide graph.  I have the decimation algorithim inside of a for loop as I do not know the total number of columns in each file.  Really I do but it changes all of the time from the Engineering department that I would like to make it adjustable/ auto configurable.

 

Is there something that I am missing when trying to decimate the arrays of data?  I am new at trying to display this many data points with LabView, typically I do this in MatLab but I don't have that ability this time around.

 

Attached is a sample file that I am trying to read, as well as my .vi.

 

Any help would be appreciated.

 

Thanks,
~Dan

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VFD - Visa

November 17, 2016, 12:01 pm
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Hello, all. I need some help. So I would like my computer to control this VFD (Kinco) I'm using, so I made a VI that would allow LabVIEW to communicate with it, but I can't seem to change the frequency of the VFD. I know it is communicating with it. I made it so that when my numeric output is less than or equal to 50 (50 being the upper frequency limit), I can extract the frequency output (this vi will be used with another vi that will read the frequency output and use it for data acquistion). I'm certain it works because when my VI runs, the serial to usb connection that connects my computer with the vfd emits a green light when the numeric output <= 50, but if it's more, the light stops. I've read the manual and tried some function codes that I thought would work but didn't. I'm stuck. Here's the VI

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Webcam image intensity acquisition

November 17, 2016, 12:10 pm
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Hi,

I am trying to use a webcam to acquire a real time video (image) and simultantously plot out the grey scale intensity from this image. The real time video part is easy and there is no problem. I started working one extracting intensity by looking at the Labview built in example called "Light Meter", which I also attached. When I compiled these two VI together, the VI did not report any error, but the grey scale intensity always stay at 0.

I have attached my VI and anyone who have experience please help me. I saw several related posts on this forum but looks like it is unsolved. Seems many people is working on similar project. I guess it would be very helpful for a lot of people if this VI can finally work.

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