Daq assist question

Im using the DAQ assist to look at counting input on my dev1 ctr3 line that goes to my counter/timer board.
Initially I was using edge count in a 10ms timed loop to count pulses. But I ran into some counting variations (i suppose this is because i am using the default 1khz clock that cannot always accurately stop the counter at 10ms)
next i tried using the frequency option on the daq assist and i specified a 10ms integration time. This seems to work much better to reduce counting error (as i am not relying on the 1khz system clock. This method however assumes that Im trying to look at phenomena that occur periodically. (my real use is to look at a stochastic process and count how many times it occurs in 10ms)
Is there anyway to specify that the board only counts for 10ms of integration time, and simply returns the number of counts it saw (rather than a frequency).
Thanks,
   Adam

Hey Adam,
Is this what you are looking for. Keep us posted and good luck
-Lab

Similar Messages

  • New project using Daq Assistant or not ?

    Hi everybody,
    I need to create a software to do some realtime acquisition & analysis.
    I trained myself a little bit on c# lessons to get use to this programming language; I’m also discovering Measurement Studio & Visual Studio. (I’ve background in C++).
    My software will have 2 modes :
    Continuous acquisition, signal plotting + signal processing & plotting (fft, 1/3 octave band filter)
    Triggered acquisition, signal plotting + signal processing & plotting (fft, , 1/3 octave band filter)
    I have examples in my National Instruments directory which don't use daq Assistant and code is different from generated files with daq Component.
    If I use Daq Assistant ( http://www.ni.com/tutorial/4652/en/ )
    I know that the code to create channel is stored in DaqTask.cs
    Plotting :
    NationalInstruments.AnalogWaveform<double>[] acquiredData = daqTaskComponent1.Read();
    waveformGraph1.PlotWaveforms(acquiredData);
    When I look to examples, like "MStudioVS2010\DotNET\Examples\DAQmxWithUI\SpectrumAnalyzer\cs "
    all code to create channel is generated in Mainform.cs, there is no Daq Assistant (http://www.ni.com/tutorial/5409/en/ )
    and there is a slight difference between acquired type :
    private AnalogWaveform<double> data = new AnalogWaveform<double>(1000);
    data = reader.EndReadWaveform(ar);
    acquiredDataWaveformGraph.PlotWaveform(data);
    Questions :
    What is the difference between AnalogWaveform<double> and AnalogWaveform<double>[] ? why it's not the same type ? I need to do some signal processing with this signal, so what type should I use for my application  ?
    I didn't succeed to configure my 2 modes in daq Assistant (continuous and triggered acquisition) is it possible or should I create 2 Items in my solution, one for continuous acquisition and on for triggered acquisition ?
    Kind regards,

    Check out the downloads section of iLounge.com. There are a handful or two of applications that will help you transfer songs from the iPod to the computer.
    Another option is to network the two computers together and transfer the iTunes folder to the new Mac. All you need is an ethernet cable and to turn on file sharing in the Sharing preference panel. Depending on how old your "older" Mac is, you might need a crossover ethernet cable.
    A third option is to hook up the two computers using a Firewire cable. On the older Mac make sure it is shut down, hook the two computers up, turn on the older Mac while holding down the "T" key. On the new Mac you should see the old Mac's hard drive show up. Just find the iTunes music folder and copy it over. You could also use the Migration Assistant which will be in the Utilities folder of the new Mac.
    Hope this helps.

  • How do I use DAQ Assistant to output DC on an AO?

    My background includes 15 years of programming PLC's. AO's were simple. You passed the AO a value between preset ranges and it output a proportional voltage signal based on the hardware capabilities.
    I foolishly thought LabView and DAQ AO's would be about the same. I built a vi to generate a DC signal which I could control the amplitude of. I also tied it to a chart to monitor how it worked. I managed to draw some very pretty ramping pictures on my chart, but when I put a DMM across the physical terminals I see no voltage.
    Then I used MAX to test the channel and measured it again. Now I see voltage on my DMM. I was attempting to use the DAQ Assistant to do this. Do I need to force it to re-read the changing value I am sending it? All of the examples I find show me more primitive methods, and I could not seem to get any of them to do what I want either. I need to send a speed reference to a DC drive.
    My incorrect method was to recursively add a value for ramping the signal up or subtract to ramp down. This method works perfectly on an industrial PLC. I connected a chart to the signal just as it entered the DAQ Assistant, but the only way I could check the actual was with the DMM.
    Are there any examples that use the Assistant? If not then I guess I will have figure out how to use the primitives anyway.
    technomage

    Hello technomage,
    It looks like we have discussed this problem in another thread (found here).  If you have any other questions about it, please post there.
    Regards,
    Jesse O.
    Applications Engineering
    National Instruments
    Jesse O. | National Instruments R&D

  • Struggling how to set up 2 daq assist on labview in the same VI

    hi all,
    hope someone can help me out
    I am currently using the scxi 2345 with some SCC FT01 feed through modules, these are just to record some voltages from some transducers.
    What I am struggling with is setting up 2 daq assist on a single VI, it is coming back with a error stating specified resouce is reserved and then a window saying learn more about automatic handling. How would I also have these 2 values logged on the same graph or chart?
    Anyone any ideas how to set these up.
    I ideally want to have 3 daq assist in the same Vi but not sure if this is possible. It would be 1 for thermocouple input and 2 for voltage as stated above
    many thanks
    shane dover

    Hi Shane and Dennis,
    I've been working my way around the same type of problems, and I am
    currently re-writing everything to use on Asst. per board on my PXI
    chassis, so that no resources become reserved.
    As a result, I have to separate the signals on the output dynamic data
    in order to do different post processing.  So I have been toying
    with staying with dynamic data, inputting dyn. data into an array, and
    inputing it into a cluster.  It seems that each has advantages and
    drawbacks, but arrays seem to be the easiest with which to work when
    splitting signals coming from a DAQmx Asst. and funneling some of the
    signals into a post-processing sub-VI.  The drawback to this is
    that time stamps in the Dyn. Data are lost if you want to record the
    data and the time of the reading. 
    Question:  Is there an easy way to pipe Dynamic Data into a
    calculation subVI?  Is it workable after it's been split from
    other streams? 
    Thanks,
    Brad

  • How can I programmatically change the voltage range settings in a DAQ Assistant

    Hi,
    First post here.  
    I need to be able to change the voltage range properties of a daqmx DAQ Assistant based on user input.  My hardware, an SCXI-1102C does not allow changing this property on a running task, so I'd like to either set the analog input voltage range before the DAQ Assistant activates, or pause the DAQ Assistant immediately after it starts, set the values and then resume.
    I don't know how to edit the task ahead of time because the DAQ assistant creates the task when it runs, and there is no task before that.
    In the attached picture, I have a conditional section, set to run only if the while loop iteration is 0.  I take the task from the Daq assistant, send it to a stop task vi, set the property, and then send the task on to the start task vi. I can watch it run with the debug light on, and everything seems to work correctly, but on the second (and all the other) iteration of the loop, I read out AI.Max and it seems like the DAQ Assistant has re set it back to 5V.  Can anyone see what is going wrong here?
    BTW, this is continuous acquisition and the code does not produce error messages when it runs.
    I did come across a similar question that someone posted here back in 2006, but his question was specifically aimed at a Labview API (VB, I think), and not an actual G solution.
    Attached are the actual vi in question and a png image of the block diagram.
    Thanks! 
    Ruby K
    Solved!
    Go to Solution.
    Attachments:
    Labview_question.PNG ‏14 KB
    Sample_AIV.vi ‏91 KB

    First, if you want to start getting beyond the basics with DAQ, you are going to have to stop using the DAQ assistant and do it with lower level DAQmx VI's.  There are hundreds of examples in the example finder.  You can even right click on the DAQ assistant and select open front panel.  That will create a subVI that you can open and see what is going on behind the scenes.  Do it.  I think you'll find the DAQ task is being recreated on each (though I'm not 100% of how the settings are established or maintained in each section of that subVI).
    The second problem is you have a bit of a race condition on iteration 0.  Those two DAQ property nodes are running at the same time.  So when you read the AI.Max, it may be happening before or after the AI.Max is set in your case structure.
    Third, make sure you wire up your error wires.

  • Using DAQ-assist to input a waveform; need help building a counter to count voltage "spikes"

    Hey all! I'm pretty new to labView and even newer to this forum, but its nice to meet you all...I hope that perhaps someone can help me with my problem.
    Allow me to begin by detailing the specifications of the problem.  I am an undergraduate student, and have a job doing research in a MEMS (micro/nanotech) lab.  The graduate student I am making this program for is working on biomedical applications;  eventually, the program will be connected to a microdevice that has a tiny channel in it, cut through a wee little capacitor, which blood will run through.  As red blood cells pass this capacitor, the voltage will spike; meaning that for each voltage spike, we can (and are trying to) count the number of red blood cells.
    However, I am still in the early developement of the program, so this above specific info is not that important.  Basically, I am using a function generator to input a waveform to the DAQ assistant of, say 500 mV.  I am trying to write a program that increments a counter every time I turn the voltage above say 550 mV (peak-to-peak), counting the number of simulated "spikes."  I have tried quite a lot to write a working program, and although I have not gotten it to work yet, I will post a screenshot of my most recent attempt HERE:
    I thank you in advance for any helpful tips, advice, or straight up assistance you may be able to give me.  Please ask me any clarifying questions about the program I wrote or the application, or anything.  Happy Friday! 

    Hey guys, it's been a while!  A lot of stuff has been happening in my life and I have had virtually no time to work on my LabView project.  
    I did create a LabView program based off IanW's reccomendation.  I am unsure of what exactly is going wrong, but when I run it, only a simple "snapshot" of a waveform from the DAQ shows up in the graph.  Even when I put the DAQ assist in a seperate while loop, the same thing happens.  I am including a screenshot of the project in case I am messing something entirely different up.  If you happen to read this, I really appreciate your help and thank you Ian! 
    I am also having a random issue with the filter signal VI.  So that background signals in the actual experiment do not read as "spikes" I have been instructed to include a high-pass filter in the VI.  However, everytime I use the high pass filter VI, it botches my signal and turns it into a bunch of noise!  I, nor my graduate mentor (who isn't too well-versed in LabView) have any idea why this is - we've tried using different types of filters to no avail.  
    Lastly, I would like to talk to Peter about a few questions I had abour LabView design.  In case you're still around, I will write another post later today with more detail.  In the meantime, I will try to find some of the example VIs about shift registers   All who read this have a great day!
    Attachments:
    count spikes pic.png ‏29 KB

  • In Labview 8.5, what happens if the signal input exceeds the signal input range set by the DAQ Assistant?

    Hello all,
    This should be a pretty simple question, but I can't seem to find the answer on-line and don't currently have the capabilities to test this:
    I'm using LabVIEW 8.5 and have a VI that imports sensor data through the DAQ Assistant. In the configuration tab there is a signal input range. What happens if my sensor exceeds this range? Will I get a warning? Will the value default to the maximum (or minimum)? I was interested in writing in some code to display an error as I approach the limits of this range, but was unsure if I also needed to include some code to display an error if the range is exceeded as well.
    Thanks for the help,
    Tristan
    Solved!
    Go to Solution.

    Hello Tristan,
    The behavior depends on the range you choose and the device you are using.
    If you are using a device with only one valid input range, we will use this range even if you set a smaller minimum and maximum in the DAQ Assistant.  Thus, if your device only supports ±10V and you set the range to ±8V, you will still continue to get valid data after your sensor exceeds 8V until you approach 10V.  Once you reach the limit of the range of your device, the output will "rail" and just return the maximum value until the signal drops below the maximum again.
    Note: A device that is nominally ±10V usually has some overshoot (like ±10.2V) that is typically specced in the manual.
    However, if you are using a device with multiple input ranges then things get more complex.
    The NI-DAQmx drive will pick the smallest range that fully encompasses the range you choose.  So, suppose your device supports the following input ranges: ±0.2V, ±1, ±5V, and ±10V and you choose 0V - 3V as the range in the DAQ assistant.  The NI-DAQmx driver is going to look at your input range and the list of input ranges that your hardware supports and choose the smallest that encompasses the full range you set.  This would the ±5V, because that's the only range that contains up to 3V.  As a result, any input signal between ±5V will be returned and any outside this range will "rail" to either the maximum or minimum value.
    We do this because using smaller ranges make more effective use of the resolution of the ADC.  Thus we try to use the most efficient range based on what you request without picking a range that will cause you to miss data.
    Let me know if I can clarify this further. 
    Seth B.
    Staff Test Engineer | National Instruments
    Certified LabVIEW Developer
    Certified TestStand Developer
    “Engineers like to solve problems. If there are no problems handily available, they will create their own problems.”- Scott Adams

  • Error with 2 Daq assistant

    Hello
    Another noob joining the community. Here is my question.
    What am i doing wrong? I use 2 Daq assistants on the NI9401 module this is for digital input and output. I use it for generating 2 signals. If i test it with 1 it works but if i go to 2 or more it fails. This is the error i get . I have also added the program as an attachment.
    Thanks in advance.
    Solved!
    Go to Solution.

    Hello,
    That error means that the DIO task is reserved and cannot be obtained by one of the DAQ assistants. There is actually a nice example program on what you want to do. It can be found here:
    https://decibel.ni.com/content/docs/DOC-11632
    This example does not use the DAQ Assistasnt but the DAQmx API VIs (which the DAQ Assistant is using also anyway). If the order is not important (and since the these DIO tasks are software timed it is probably not an issue you can also choose to use the error cluster from one DAQ assistant and wire it to the other (see attached VI). Doing it that way you force one DAQ task to wait for the other one to finish. In that way they cannot run at the same time preventing for the error to happen.
    regards,
    Rik Prins, CLD
    Applications Engineering Specialist Northern Europe, National Instruments
    Please tip your answer providers with kudos.
    Any attached Code is provided As Is. It has not been tested or validated as a product, for use in a deployed application or system,
    or for use in hazardous environments. You assume all risks for use of the Code and use of the Code is subject
    to the Sample Code License Terms which can be found at: http://ni.com/samplecodelicense
    Attachments:
    2 Daq assistant generating error (3).vi ‏169 KB

  • How can I link my daqmx code to another daq assistant to hear my audio output?

    Hi,
    I got a burning question about my school project. I need to use labview and my NI-mydaq to test the difference between
    various samples rates and bit depths.
    I linked an mp3 file to the AUDIO IN of my NI-mydaq and created a way to be able of switching sample rate while running my program.
    Now I would like to link my program inside the NI-mydaq to my AUDIO OUT...
    So...  I generated daqmx code out of an input daq assistant, how can I link my daqmx code to another daq assistant to hear my audio output?

    Hello Fontys_Student...,
    I am not sure I properly understand your question.
    You want to, first, acquire a signal from the AUDIO IN input, second, do some processing on the acquired signal and, third, generate this processed signal at the AUDIO OUT, right? What is the part causing some troubles?
    If you already have the signal acquired and processed, you can simply wire this processed signal to the "data" input of a second DAQ Assistant, right?
    Did you already have a look at the myDAQ User Guide (http://www.ni.com/pdf/manuals/373060e.pdf)? On page 32-35, there is an example showing what you need I suppose. 
    Cédric | NI Belgium

  • DAQ Assistant: Clock Settings (Samples To Read, Rate) can affect signal readings?

    Dear all,
    I'm totally new to Labview, and recently I get confused with the equipment I'm dealing with.
    Technical details:
    The Labview version is 7.1; computer operate system is Windows XP;
    The equipment has a NI PCI-6220 and a 68 Pin Connector Block to read signals from the equipment;
    There are 4 channels in DAQ Assistant (2 pressure reading, 2 temperature reading);
    For the first pressure reading, Signal Input Range from 4m to 20m Amps;
    Clock Settings are Samples To Read = 5, Rate (Hz) = 20.
    Description of the problem:
    I use Labvew to monitor and record pressure readings and temperature readings. The Labview configuration was set up by my advisor several years ago. Recently, I found the pressure reading vibrated a lot; for example, 5.01 to 5.05 bar within a second. In order to get a stable pressure reading, my advisor suggested me to change "Clock Settings" in DAQ Assistant from Samples To Read = 5, Rate (Hz) = 20, to Samples To Read = 250, Rate (Hz) = 1000. In this case, she believed that since we increase sample numbers and sampling rate, we could have more data, and thus have stable pressure readings.
    At first I could have very stable pressure reading. The last digit (0.01) did not change within 20 seconds. However, somehow after a day the pressure reading became unstable and even worse than previous. (pressure reading vibrates from 5.01 to 5.30 within a second)
    This is not the worst case. We found that when we set Clock Settings: Samples To Read = 5, Rate (Hz) = 20, the pressure reading is about 8 bar. However, when we set Clock Settings: Samples To Read = 250, Rate (Hz) = 1000, the pressure reading is about 5 bar. In this case, we even don't know which pressure reading is correct.
    Labview records current, and transforms it into pressure reading. Thus my advisor tried to monitor the current reading by Labview, and she found the current reading changed when she changed the Clock Settings. (0.004 Amps (5 bar) when Samples To Read = 5, Rate (Hz) = 20; 0.005 Amps (8 bar) when Samples To Read = 250, Rate (Hz) = 1000)
    Since we only change the sample numbers and sampling rate, the average readings should still be similar. However, the reading are not similar. That is what confuses me.
    My questions are, if Clock Settings in DAQ Assistant could affect signal readings? If so, how it could affect the signal readings? What is the effect of "Samples To Read" and "Rate (Hz)"? How to determine these parameters to get the true pressure readings?
    Thank you very much for your help. Hope to have some feedbacks from you.
    Best regards,
    Cheng-Yu
    Energy and Mineral Engineering
    the Pennsylvania State University

    A 6220 cannot read a current, it can only read a Voltage, so you'll probably have some (or should have) a resistor accros the voltage input. (normally 50 Ohm for a 0-20 mA signal).
    My first step would be to measure this voltage with a multi-meter so you know what the actual voltage should be.
    Then I would read that same voltage with MAX (measurement and automation explorer) to make sure you have the right value
    Now about the changing of the voltage/current/pressure, how have you terminated the other signals? Have you provided a good earthing?
    If you sample with a high frequency (1 kHz), perform an FFT on the acquired data, I can imagine a dominant 50 or 60 Hz (depends on where you live) in the signal that might cause your problem.
    Ton
    Free Code Capture Tool! Version 2.1.3 with comments, web-upload, back-save and snippets!
    Nederlandse LabVIEW user groep www.lvug.nl
    My LabVIEW Ideas
    LabVIEW, programming like it should be!

  • Sample clock of DAQ assistant

    I am using DAQ assistant to generate output voltage and another DAQ assistant to measure input voltage. I am to sepecify teh clock type for the two DAQs. I want the same clock type for both the DAQs so that the data from both DAqs are synchronized, that is run with the same clock. I m not using any external clock and want it software timing. I want to know if it is okay to select internal clock type for the output voltage DAQ assistant and then select external clock type for the input voltage DAQ assistant and select the clock source as the analog output sample clock?
    OR if i select the clock type as internal for both the DAQ assistants will the data be synchronized?

    Hi Amber,
    Analog Input is not retriggerable,
    meaning that once you stop the task you have to restart the entire task
    (including the analog output). But if you want to just stop displaying the data
    on the input channel, simply encase the Measurement
    output in a case structure with a Boolean control that you can click to update
    the graph or not.
    If that doesn’t work for what you’re
    trying to do, please give more details as to your overall application so the
    community can help answer your specific questions.
    Mark E.
    Precision DC Product Support Engineer
    National Instruments
    Digital Multimeters (DMMs) and LCR Meters
    Programmable Power Supplies and Source Measure Units
    Attachments:
    Not update voltage.png ‏5 KB

  • There are no inputs or outputs on the DAQ assistant to connect to

    Hi everybody,
    I am new to labview and have run into some difficulties with the DAQ assistant.  I am running labview v8.0, NI-DAQmx v8.7.1 and  have a PCI-6224 DAQ installed.  It seems that when ever I drop the DAQ assistant (the instrument assistant, and the simulated DAQ has the same issue) onto the block diagram, and configure it, there are no inputs or output which I can wire a control or indiactor to.  Is there a step that I am missing somewhere? 
    Thanks in advance!
    Solved!
    Go to Solution.

    Sorry, forgot to attach the end result. Note I did have errors come up, they may have been due to no DAQ cards in my PC.
    -AK2DM
    ~~~~~~~~~~~~~~~~~~~~~~~~~~
    "It’s the questions that drive us.”
    ~~~~~~~~~~~~~~~~~~~~~~~~~~
    Attachments:
    daq_test[2].vi ‏83 KB

  • Can't launch DAQ assistant in LabVIEW

    Hi
    I cannot launch DAQ assistant from LabVIEW, but i can do that from MAX. DAQ from MAX is not that flexible because i can't customized the code or convert it.  I 've tried all the various ways to open DAQ assistant and i finally realized something, on the block diagram, i open Tools/Advance/Edit palette/Express/Input/DAQ is missing (question mark) and many more functions are missing.
    I'm using  the evaluation software of Labview 8.6 and NIDAQmx 8.7.1
    Can you please tell me what is wrong. I really need to launch NI DAQmx from LabVIEW.
    Rgds
    Paul
    Solved!
    Go to Solution.

    Hi Christ
    Thanks for the feedback.
    From Block diagram interface: Function palette/Measurement
    I/O ? (there is nothing just MAX config).
    But from Front Panel: Modern/ I/O controls, i can see DAQmx names controls
    which i don't think i need now.
    What do  mean reintalling DAQmx with LV
    support, is it different from the LabVIEW evaluation software or i just have to
    reinstall the LV
    evaluation software.
    Rgds
    Paul

  • DAQ-Assist crashes Labview....

    Hi,
      I'm running Labview 8.0.1
     I use the DAQ-Assist to read info from some channels.....
     I drag the icon on my block diagram, which automatically opens the wizard. I setup channels, type of signal (voltage, current, etc), hit OK and after ~30 seconds (where LV says first "Verifying task' and then "Building VI, please wait"), it creates an ExpressVI without any problems.
     The problem is whenever I try to edit/change/add settings.... Say that later I wanna change the voltage range on one of the channels, or add another channel. I go in (double click on the icon), make the changes and when I hit OK, LV crashes after about 15 or 20 seconds of displaying the "buidling VI, please wait" message.
     Usually I have to re-create the whole thing (drag a second icon, and delete the first one) to avoid the problem.
     I've seen this happen even with new VI's that I create from scratch. It happens 95% of the time, other times it works flawlessly.
     What's wrong?
    Attachments:
    DAQ-Assist-error.JPG ‏187 KB

    Hello Emerino,
    Thanks for contacting National Instruments. 
    It looks like there is an issue with the installation of either your DAQ driver.  The knowledgebase LabVIEW Application Error: The instruction at address x referenced memory at address y. The memory c... goes over possible causes of the error you are seeing.  Most likely a file in your LabVIEW or DAQmx install has become corrupted and is causing LabVIEW to crash. 
    First, attempt to repair all of your NI software.  This can be done by going to the Add or Remove Programs screen and clicking the change/remove button next to the National Instruments Software selection.  This will bring up a list of all of the installed NI software that is on your computer.  Highlight all of this software and choose to repair.  During this process the installer will ask for the LabVIEW CDs as well as locations of any installers that were downloaded to your hard drive. 
    If you are still having trouble running your DAQ assistant, update to the latest version of DAQmx.  This will have updates to numerous known issues as well as increase the stability of the DAQmx driver. 
    The Investigate Previous Internal Error window you are seeing after a crash is a way for you to report any unexpected errors in LabVIEW that caused it to shut down.  If you choose to report the error, National Instruments can use the information to improve its software products.  This window should only appear when opening LabVIEW after a crash occurs. 
    Please post back if you continue to have issues or if you have any questions. 
    Regards,
    Browning G
    FlexRIO R&D

  • VI DAQ assistant

    En utilisant le VI DAQ assistant, je n'ai pas acces aux entrées ni sorties du VI.j'ai réinstallé les drivers DAQmx croyant que c'etait ça le probleme sans succes...Quelqu'un a t il déjà eu ce problème?

    Hello tdiak,
    Please keep in mind that this the English section of the forum. (this is the French forum: http://forums.ni.com/t5/Le-forum-francophone/ct-p/FrenchForums)
    So posting a French question over here might not get as much response.
    Seeing that I do speak/write/read French I'll try my best to help you.
    Can you give some more information of what you mean with "no access" to inputs or outputs?
    Have you ever Used LabVIEW or DAQ Assistant before or is it your first time?
    Kind Regards,
    Thierry C - Applications Engineering Specialist Northern European Region - National Instruments
    CLD, CTA
    If someone helped you, let them know. Mark as solved and/or give a kudo.

Maybe you are looking for