Plot from two DAQ readings on opposing axis

I have a DAQ system taking two different readings. I want to plot them both on the same graph with one reading, say temperature, on the X-axis and the other, say humidity, on the Y-axis. How do I do this?

Hi mbooker,
you should write "DAQ Assistent Express VI" whenever you mention "DAQ system"!
If you would use "plain" DAQmx functions you wouldn't have to go all the way through datatype conversion from DDT to meaningful representation...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Similar Messages

  • How to plot two analogue inputs from a DAQ device against eachother on an XY graph

    I am trying to separate data I am acquiring from two analogue inputs on my NI USB-6009 in order to plot them againt one another on an XY graph. I have tried setting up two DAQ assistants on the block diagram, one acquiring data from ai0 and the other from ai1. I tried to wire these to the X input and Y input respectively and running in a while loop but Error -50103 shows up.
    I've read through a few discussion threads and have found that you should acquire the data from both analogue inputs thorugh one DAQ assistant, useing index arrays to split the data and wire to the X input and Y input of the XY graph, but I cannot figure out how to do this.
    Any help would be greatly appreciated!

    It's pretty trivial to use a single DAQ Assistant. When you create one, you are given the option for multiple channels and shown how to select them. Once created with a single channel, you simply open the assistant and click on the Add button. After the acquisition, you use the spilt signal function if you stick with the evil dynamic data.

  • Plotting x and y axis from two different data

    Hi everyone,
    I've just started using LabView on my new job. My new task is to create a VI to display a plot an XY graph from two data. How do I actually assign the two different data (X and Y axis resepctively)and plot them out on a same graph??
    Please help me out... my job is on the line!

    Other may post an example for you.
    I will tell how to find this and many other answers.
    Do a "Find Examples" from either the LV open screen or from the Help drop down.
    LV ships with examples that demonstrate almost every basic operation.
    One of the big benifits of these examples is that they work! If they do not, NI is interested in finding which ones do not.
    Ben
    Ben Rayner
    I am currently active on.. MainStream Preppers
    Rayner's Ridge is under construction

  • Acquiring a signal from two separate DAQs at different rates at the same time

    Hi I am trying to setup a system where I need to build two separate arrays one from two separate sets of data. The data needs to be brought in at the same time, but at a different rate. One set is from the PCI-4472 and will come in at ~10Hz, while the other is from a SCXI-1102 that is connected one channel on a PCI-6070E at ~3-5Hz. I was wondering how to have the two be read at the same time, but at the different speed. I am using LabView 6.1. Thanks in advance.

    Hi Muheesh:
    Since your DAQ's are working at an exact multiple of one another, what you could do is fill alternate channels with some "DUMMY" data...like zeros. Then you could index the array and match it up with the faster card. It might seem like a waste of memory, but it will give you two sets of aligned data, which seems to be what you need. If you're operating them at some weird multiple, it's a bit trickier. Whatever you do, you're going to have to insert some bits somewhere. Look for a least common factor (LCF) of your sample rates, and see if you can divide by that before logging the data.
    Eric
    Eric P. Nichols
    P.O. Box 56235
    North Pole, AK 99705

  • How to calculate the phase difference between two square wave (acquired from two channel in one DAQ)

    Hello everyone ,
     I need a quickly help that as below :
    I am trying use PCI-6220 to acquired six signals from one rotation encoder (channel A, channel B,channel Z ,and their non-signals) .The encoder out signals will be square wave and 4000pulses per revolution. I set it rotation at 300rpm speed. I need show every square wave of six out channels in waveform and measure the A-B phase difference to check if the value is correct (designed value should be 90deg) .
    I have no idea how to measure or calculate the phase difference of two square wave base on synchronizate to acquire these two square wave from two channel on the PCI-6620....
    Anyone can give a idea how to calculate the phase difference with two square wave ?
    Thank a lot and Thanks again...
    Tim

    Tim,
    Here is a simple rising edge detector for one channel.
    Lynn
    Attachments:
    Rising edge.vi ‏15 KB

  • Mutiple readings from Express DAQ Assistant VI

    Hello All!
    First I'm a fresh noob to LabView and although I understand most of the basic concepts, I'm also new to programming in general. I'm working on a project to remotely monitor several different parameters of a system. Right now I'm working on a test program to monitor three parameters in my shop across the street. I'm using a NI USB-6008 as a DAQ device, DAQmx 8.0 and LabView 8.0. All of my input signals are 4-20 mA signals coming from my three sensing devices. 
    Here's my problem; I need to monitor all three signals on digital displays. I can accomplish this by using three different instances of the express DAQ assistant but then I get the dreaded "50103 error" unless I wire the stopped output of one assistant to the stop input of the next in a feedback loop and even then I get the 50103 error on the first iteration of the loop. From my research I understand that this isn't the correct way to program this. I should use one DAQ assistant with multiple channels assigned to each one of my parameters. I've did this but now how do I make each one read out on an individual digital display? I only have one output from my DAQ assistant.

    Hi George,
    Use split signal in the signal manipulation functions menu to get your 3 individual singals on respective indicators
    Regards
    Dev
    Attachments:
    SPLIT.vi ‏85 KB

  • How can I tell if signals from two devices are truly synchronised?

    Hi there,
    How does one check that signals from two devices (two separate devices in a single X-series chassis) that should be synchronised actually are?   I am using a PXIe6361 and PXIe4331 on a PXIe-1073, with Labview 2001 SP1 64-bit. All devices are using the Sample Clock from the 4331 device, and an AI Start Trigger, so they should be synchronised.
    I thought that writing the signal data to file and checking the time stamp for each column of data would be the most accurate, but I have been told that timestamps are software created and therefore don't reflect the actual time that the signals were acquired by the hardware.  When I do this, the timestamps vary by up to 150ms which is larger than I expected.
    If I set the x-axis of the waveform graphs (on the GUI) to "Time" then it appears that the first data sample is taken at different times for the two plots (one plot per device).
    If I set the x-axis of the waveform graphs (on the GUI) to "Ignore time stamp" (so that the x-axis just starts from 0 rather than a date-time) then the first data point occurs at "0" for both graphs. However, I'm not sure that this reflects the actual alignment of the signal.
    What is the best way to check if signals collected on different devices in the same chassis are actually synchronised?
    Thanks,
    Claire.

    Hi Lynn,
    Thanks for your help and for sending the demo.
    I understand the concept of how the signals will look if they're not synchronised and your demo shows that nicely. I guess I have been perplexed by someone else telling me that the timestamps in the output file (and following from that I assume timestamps on a waveform graph) do not give an indication of whether signals are synchronised. The reason they gave for this was that the timestamps are manufactured by the software, not the DAQ hardware.  They suggested that I put the setting "ignore waveform timestamps" on my waveform graphs, and then check that both signals come in at the same time (i.e. both start at zero), but I'm not convinced about this. 
    When I use an analog trigger, neither the timestamps in my output file or on the two waveform graphs are synchronised. If I don't use the trigger, then there is far less disparity in the timestamps in the output file. I've attached two output files here, and my VI.
    This is my first attempt to synchronise a voltage module and a strain gauge module on an X-series chassis, so I want to make sure that I'm achieving the best synchronisation that I can, and the difference in behaviour with and without the trigger worries me.
    Thanks,
    Claire.
    Attachments:
    without trigger.txt ‏5 KB
    with trigger.txt ‏6 KB
    Multi-Device Synch-Analog Input-Finite Acq-Analog Start_Claire_wDigitalin_12June2012 PTbridge.vi ‏196 KB

  • Can users have one iTunes library deriving from two drives?

    Hi everyone,
    I keep my 4 & 5 star songs on my C drive and the rest (all stars, 1,2 3, etc.) on my exhternal hard drive.
    Whenever I want to listen to my music, all I can readily play are the tunes on my C drive.
    I'm guessing the issues having one library for tunes stored on separate drives is insurmountable?
    I say that because I'm guessing that my iPod (4th gen) is only capable of importing from one library?
    I think the biggest issue is either I don't know how to (or maybe users can't) list a second drive so that iTunes can load all songs from both drives whenever I do have the second drive up and running.
    Adding to the second drive library issue, I can't figure out how to permanently tag my external HD's (I've got 6) so that their drive letter is not automatically defaulting to their order of prescence.
    I can deal with that issue by simply not opening iTunes while I the second drive has been assigned a drive letter other than what iTunes (hopefully) is set to (i.e.; hopefully C and F drives).
    But can users have one iTunes library deriving from two drives?

    Seems I've over come what is something I'd hoped/expected iTunes would be capable of (ie; reinitiating the pathway for external HD music files when their drive letter is the only thing that changed).
    I tried the obvious by going to iTunes's Edit>Preferences>Advanced and clicking the change button for "iTunes Music folder location", then entered the current drive and pathway (as the drive is currently assigned, F as opposed to the original G) and of course iTunes still couldn;t find the missing tunes.
    Giving up on the hope that iTunes was designed smarter than it is (ie; each and every single missing tune req's manual redirection of pathway, as opposed to a preferable tick box for something like 'use the last redirected pathway').
    And I finally figured out how to properly changed drive letter assignments, but still uncertasin if that means permanently tags my EHD's with that drive letter.
    For that to be permanent, maybe I need to name each drive regardless that Windows already has unique inforamtion on each HD. Suppose I'll soon find out if the drive at this point has fianlly stored its drive name and whether or not Windows will contiue to change the EHD drive letters simply by the order which I am introducing them to the os.
    No real luck with rats nest USB hubs as they crash my os alot, so I'm left to trying to find an easy way of managing the EHD drive assignments. THe following is the closest I've yet to come to doing that:
    Click Start>Control Panel>Administrative Tools>Computer Management, and then in the left pane, under Storage, click Disk Management.
    Right-click the drive, partition, logical drive, or volume for which you want to assign a drive letter, and then click Change Drive Letter and Paths.
    Click Change.
    Click Assign the following drive letter (if it is not already selected), click the drive letter that you want to use, and then click OK.
    Click Yes when you are prompted to confirm the drive letter change.
    Again, too bad iTunes doesn't afford a 'find' feature for 'missing' files such that one might be afforded a tick box for 'do not prompt again, instead use the last indicated location for "iTunes Music" folder as the base storage location'.
    This drive renaming thing is a real hassle. Not like somebody couldn't have guessed it and Windows and/or iTunes can't afford some script, etc. to better manage 'tagging' EHD's and/or re-locating 'missing' tunes.
    But then what would we have to complain about, not that they listen anyway.

  • 3d graph plot from .txt

    Hi
    I have some .txt datas which I want to visualize. I need one of the wavelenght columns as x axis; and the last column OE1_Channel1 as z axis. Last I have ~100 .txt which should build the y axis.
    I dont know how to go on, "delete from array" seems to be not enough, and I have no idea how to build this plot from several .txts

    This is what I did befor, but I haven´t discovered yet how to make one row the y axis and how to make several txts the x axis.
    Attachments:
    txt to 3d-graph.vi ‏55 KB

  • I have a plot with two cursors - how can I control the "visible" attribute of the second cursor?

    I have a waveform graph with multiple plots and two cursors. I can use the "cursor->visible" property to control cursor #1 but I cannot seem to find a way to control the visible attribute for cursor #2. Is there a way to do this?
    Thanks,
    RGA

    There's an "Active Cursor" property that allows you select which cursor the following actions operate on. Remember that property nodes "execute" from top to bottom...
    Mike...
    Certified Professional Instructor
    Certified LabVIEW Architect
    LabVIEW Champion
    "... after all, He's not a tame lion..."
    Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

  • Samples missing when two DAQ boards synchronised

    I am attempting to synchronise the input from two NI DAQ cards using the RTSI bus: an analogue PCI-6110 card (slave) and a digital PCI-DIO32HS card (master). I think I have the cards working OK together now and they appear to be taking samples in sync. However, although both cards are configured with the same size buffer the analogue card never seems to complete it's aquisition and always records 3 scans less than the digital card. Does anyone know why this happens or how to get both cards to aquire the same amount of scans.
    See attached code for details. Cheers, Tim
    Attachments:
    Analogue and Digital Capture11.vi ‏4658 KB

    I believe the 6110 has a analog input pipeline depth of three samples. This is from the NI-DAQmx help under Device Considerations -> Timing -> S Series: if the pipeline depth for a device is three, the first sample will be acquired on clock tick 1, but it will not be available for reading until clock tick 4. Following this logic, you must supply pipeline depth extra clock pulses for a finite acquisition to flush the pipeline.

  • SaveToFile example modificati​on to get data from two channels simultaneo​usly.

    We are trying to modify the “SaveToFile” example for C++. This particular example comes with NI-scope 2.9.1 and some other versions. This example collects data from one channel and saves the output as a text file. Also, we are using NI PCI-5112 DAQ.
    However, it can be modified to get data from channel 0 and channel 1 at the same time. There is a help file called “Fetching Multiple-Record Acquisitions”, which is under the NI-High speed digitizer help topics. This confirms that you can modify the code to get data from two channels and the output will be a text file where every other value is from one channel. This help file also gives some code. However, it is not very much helpful to us, please keep in mind that we have only taken a basic course in C++.
    Our project is to analyze the data, however, we need to acquire the data before we can analyze. We have spent so much time trying to get the data.  What we need to do is get data from both channels simultaneously and output the data as a text file.
    Can anyone help us to modify the code so it can get data from both channels simultaneously? Or can anyone help as where we can get more information? Or does anyone know of any sample examples that will take data from two channels simultaneously and output the data as a text file or any other type of document.
    Any help will be really appreciated, as we have spent so much time trying to acquire the data.
    Thanks.

    Hi Finomad,
    Please see this post for an answer to your question.
    Regards,
    Natasa

  • Fast array building from two independent acquisitions

    Hi all,
    I'm trying to figure out a way to build an array very quickly (up to 5 kHz) from two independent acquisitions.  For the two acquisitions I have a counter input from an encoder and a normal analog input, the purpose is to correlate with high resolution a position to an output voltage.  I can run each independently fast enough, but the problem I'm having is figuring out how to line up the two signals into a single array simultaneously and at a consistent rate (5 kHz) to write out to a file.  My first hack was to read the two outputs into a while loop clocked by a wait timer, but the best I think I can do there is a 1 millisec wait which gives me no better than 1 kHz.  Any ideas?  Hopefully something simple I'm overlooking.  Running LabVIEW 7.1 on a PCI-6036E card.  Thanks in advance.

    You're going to have to use hardware timing on the DAQ card and acquire multiple samples on each scan.
    If you're using DAQmx (and you really should be), change the Read VI to
    acquire multiple smaples from multiple channels. This single VI can
    scan both channels and output a 2D array with each channels data in one
    row of the array.
    You'll also need to change your configuration setup to specify both channels and the smapling rate.
    If you look in the Example Finder (Help menu>Find Examples...)
    double click through "Hardware Input and Output">"DAQmx">"Analog
    Measurments">"Voltage" you'll see several examples that do this sort
    of measurment. Most of them only show how to acquire a single channel,
    but can be easily modified to include a second channel.
    Let us know if you need more help.
    Ed
    Ed Dickens - Certified LabVIEW Architect - DISTek Integration, Inc. - NI Certified Alliance Partner
    Using the Abort button to stop your VI is like using a tree to stop your car. It works, but there may be consequences.

  • Stop plots from continuously updating in edit mode

    I have many plots on a graph in the Report section of DIAdem. When I am trying to put lables in for the axes and a title for the plot, every move I make I have to wait like 10 seconds because it re-updates all the plots. Is there a way to stop the plots from continuously updating during the edit phase?

    Hello amaglio,
    I have another indirect suggestion that might help with your questions.
    Starting with DIAdem 2011 we have a new display type that allows you to add points to graphs programmatically, i.e. you will be able to enter the X and Y of a curve you wish to point to and DIAdem will draw an arrow to that point, and move it when you resize an axis system. See example plot below.
    You can join the Beta test for DIAdem 2011 and test this for yourself at http://www.ni.com/beta - you can use my email address (our email addresses are [email protected]) for the NI reference to participate in the Beta test.
    I know that doesn't solve your immediate issue, but it might solve your problem when DIAdem 2011 is released and you will be able to automate the task you are right now doing manually.
    I hope this helps a little.
         Otmar
    Otmar D. Foehner
    Business Development Manager
    DIAdem and Test Data Management
    National Instruments
    Austin, TX - USA
    "For an optimist the glass is half full, for a pessimist it's half empty, and for an engineer is twice bigger than necessary."

  • Capturing From Two Different Sources

    Hello, how reliable is it to capture from two different sources using the following sceario:
    1. Powerbook G4 15" Using the digital optical audio input for sound and using the DV 1394 Input for DV video
    2. In FCP, selecting "Digital Optical Input" for AUDIO and DV for video
    3. Hit capture now since it is going to be recorded live
    Any thoughts folks?
    Trying to avoid bying the firestore $8,000 solution

    Hi,
    I don't see any problems in that scenario - if your disc is fast enough, that is! I've never worked with a G4 Powebook but in theory, it all comes down to the spped of the storage you have. The safest scenariio, az suggested above, would be to try it beforehand. You should also considerthe length of the live recording as opposed to the disc space you have. I don't know about the "firestore" solution but a firewire "LaCie" external disc is a cheap solution and it works fine with the G4 Powebook. Another issue is what FCP compressor to use during capture! Try it!

Maybe you are looking for