Waveform chart number of clusters

I am in the process of modifying a VI worked up by one of my coworkers. My setup has 4 waveforms coming into a "Bundle" block and then the resulting cluster going to a waveform chart. My coworker's VI was working with 8 waveforms. When I copied his waveform chart into my VI and tried to connect the bundle of now 4 waveforms to that waveform chart, it gives me the error "You have connected 2 clusters with different contents. Clusters (unnamed), a cluster of 4 elements, conflicts with cluster waveform chart, a cluster of 8 elements." How do I change the number of elements that the waveform chart is expecting? I've been poking around at it for a couple hours and havn't found a solution. I tried creating a new chart but can't figure out how to make it accept clusters instead of the default double precision input. Let me know if you need more description. Thanks.

I don't think it's possible to send in a cluster of waveforms to a waveform chart at all, regardless of how many waveforms are in the cluster. To send in multiple waveforms into a waveform chart, build them into an array of waveforms.
You do need to bundle scalar data into a cluster when sending multiple single-point signals into a waveform chart so that the waveform chart doesn't confuse an array of separate signals with an array of values from one individual signal.
Charts automatically change to the data type that is input into them. By default, they're scalar doubles. If you wire a cluster of scalars into them, then they change into scalars. My guess is you had a waveform chart configured to be a cluster of scalars, and then you were trying to wire an cluster of waveforms into it.
In any case, always refer to the example Charts.vi in the Example Finder (Help >> Find Examples from LabVIEW) for examples of properly sending in data to waveform charts. For waveform graphs, the example is called Waveform Graph.vi, and for XY graphs the example is called XY Chart.vi. Hope this helps!
Jarrod S.
National Instruments

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DynamicStackPlots here:
http://sine.ni.com/apps/utf8/niepd_web_display.display_epd4?p_guid=B123AE0CB938111EE034080020E74861

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My waveform chart is suppose to be with respect to time but I've noticed it is plotted with respect to the number of times through my VI

I was under the assumption that waveform charts in LabVIEW 6i atomaticly displayed wired data with respect to time in seconds. However, I noticed that my chart plots data with respect to the number of data points my VI has generated. Is there anyway to fix this so that the chart actually plots vs. time. I've attached VI. The CIN is to a Computerboards Inc, thermocouple. Any help would be appreciated.
Attachments:
tepTInScan.VI ‏73 KB

It appears that the chart is set to display relative time but since you don't have the acquisition in any kind of a loop, your relative time is pretty meaningless. You've got the dX of the chart set to be one, so yeah, at the beginning, the x scale numbers are going to be the same as the number of aquisitions until you've run it more than 60 times. At this point, you'll see the x scale show minutes and seconds. If you want absolute time for the x scale, look at the examples Real-Time Chart.vi or Variable-Time Chart XY.vi.

How do you change the Number of Plots Shown property of a Waveform Chart at runtime?

Is there any possible way to change the Number of Plots Shown property
of a Waveform Chart at runtime? Thy Dynamic Stackplots example is
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There's a couple of ways to do this -
1. Manage the data going into the chart to only be what you want displayed
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2006 Ultimate LabVIEW G-eek.
Attachments:
MultiPlots.vi ‏48 KB

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Right click on the chart and select Chart History Length. Enter the value that you need. The maximum is 2147483647 points.

Display Data on waveform chart or XY graph over a long period of time

Display Data on waveform chart or XY graph over a long period of time
Can anyone help?
I am acquiring data from an Ni DAQ card with the following parameters - sample rate = 12800, number of samples = 4096. I want to extract order information so as to track changes in the amplitudes of certain frequency harmonics. So I use the sound and vibration toolkit to extract this information as shown in the attached Vi. I will like to plot the resulting amplitudes against real-time starting at the time the Vi was run. I really want the display to show these changes over long periods (eg. days, months and even years).
Problem.
I have tried to plot the Y component of the resulting magnitude for a given order on a waveform chart. My choice of the waveform chart is because I also want to display alarm limits (using the mask and limit vi) (I can't have these lines displayed on an XY graph plot). I tried adjusting the scale offset using the property node and setting the offset to current time. However, the display on the X-axis can only show a span of 2 minutes as will be seen when you run the attached vi. I want the time display on the x-axis to be over a period of days, months and even years. Is there a way to set the maximum scale on the x-axis to be say a year or so in future.
I really want the display to be like the one in in the second attachment.
Attached is a sample VI created using an Ni USB 9234 DAQ card. Any card will do but I am only getting the signal from one channel for this example
I will appreciate any help that can be given to me.
Thanks
Attachments:
Real-Time Graph Display.vi ‏170 KB
Sampe screen1.doc ‏37 KB

Long term testing can be tricky- and we'l get into that later. Lets start with the basics that you have wrong.
The vi as you have constructed it has only one memory element, the chart history length (default is 1024.)
You can change the number of points the Chart will remember by Right-clicking the chart an select Chart History Length from the menu.
But for a long term test - and one where you want to REMEMBER the first value you need a memeory element that is independant of the application. Your PC WILL loose power or need to be rebooted eventually. Heck it might even need to be replaced! you really need to store your data in a file. Preferablly in a file that is backed-up on a regular basis so you don't lose every point of data if the PC dies. It realy hurts when you have to restart a 2yr test because you've lost the 18months of data you collected.
For an application like this I would seperate my "collection" and "Evaluation" operations.
Have one vi that takes the reading and writes it to a file at a configurable rate You may want 1reading per minute for seveal days then 1 per hour for a few weeks- then maybe only once or twice a week for the next couple of years since you are looking for LONG TERM stability. having too much data to evaluate can take a lot of digging to find the few things that interest you (but always take more that you think you need)
Have another utility that COPIES the files, reads them and displays the data you are interested in that day. The data you want to look at won't change over time HOWEVER, you WILL want to analize it in different ways depending on what the data trends look like. Having seperate routines for collection and display allows you to update the display style and analisys without even stopping the collection vi (much less editing the vi)
Jeff

How can I display more than 1 loop iteraction in a waveform chart?

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The default history length of a chart is 1024. To make it longer is a right click option.

How to take the print out of the entire data from the waveform chart

i am using cont acq to spreadsheet file.vi to acquire data from a number of channels. this vi also plots the acquired data on the waveform chart. i want to take the print out of the entire data. how can i do it ?
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There are a number of different ways of achieving your goal. Depending on which version of LabVIEW you have and which development environment, the Report Generation Toolkit is a very powerful tool. Attached is an example that prints the acquired data without the use of additional toolkits.
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Attachments:
DAQ_with_Print.llb ‏115 KB

Auto update waveform chart error

Hi all!
I have come across the problem when working on my VI. As you can see from the VI that I have attached, there is a waveform graph on the front panel for data acquisition. The value shown right now is from time, 00:00:00 to 00:05:00 (0-5minutes).
The problem that I am faced right now is, everytime when I hit the run button, LABVIEW seems to automatically change my time value to some sort of generic time. What I want to accomplish here is that, I want to acquire data on the waveform graph from time 0 to 5 minutes. Also, I would like to specify the increments myself. For example on the time scale (x-axis) from 0-5 minuntes, I would like a 30 seconds interval between them. How do I actually accomplish it?
I have tried absolute time format and changing my waveform chart to sweep chart.
Thanks for any help!
Jlam
Attachments:
PDaq- Modified_07-08-2010.vi ‏61 KB

The problem here is that Waveform Charts and Graphs always assume a constant delta time between data points. If you are absolutely certain the data points are guaranteed to be sampled at consistent intervals, the Waveform Chart or Graph is a good fit for the data.
On the other hand, if data points are sampled at arbitrary time intervals, it will be necessary to use the XY graph, where different timestamps for each data sample determine the t-axis (time, horizontal axis).
The deal here is that your horizontal axis is N, Sample Number, not t, sample time. Your samples start at 0, and increment 1, 2, 3... Therefore, if you are taking 120S/sec, it will appear two minutes - 00:02:00 (HH:MMS) - have elapsed in the first second! One way to convert Sample Number to Time is by mulitplying that scale by the factor 1/120. To add a multiplier (or offset) to your scale, go to the properties of the Chart. Likewise, you can use a property node to programmatically set scaling factors on the scale.
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Only first plot of waveform chart has run-time menu

Hello again all you helpful forum-goers!
My multi-plot waveform chart is working decently well, but now for some reason only the first plot in the plot legend displays a run-time customization menu when I click on it while the VI is running (allowing me to select the plot color, etc.). All the other plots do nothing when I click on them. I do not have any mouse-down events or filter events of any kind in my VI. I programmatically set the number of plots and the size of the plot legend, along with each plot's name, y index, and color. Any ideas as to what might be going on?
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Solved!
Go to Solution.

Okay, hopefully this will help get some more thoughts / answers flowing. I've copied my strip chart from my actual VI into a test VI, and it still exhibits the problem. On the other hand, I have created a new strip chart from scratch, and it works fine. I have attached both VIs here for you to see. My guess is that some property of the first chart is set incorrectly or something, but I cannot figure out which one (and there are so many!).
Any assistance you can give would be appreciated. The challenge is to get the chart in the first VI working (plots other than the first responding to a mouse click to change their color or other attributes), via changing some attribute of the chart (and being able to tell me which one you changed!).
Thank you again for anyone who can look into this.
-Joe
Attachments:
Test StripChart color selection not working.vi ‏17 KB
Test StripChart color selection working.vi ‏12 KB

Waveform chart slow to read samples AIs when sending AOs

Hi all,
I am using labview to sample AI signals and send AO signals sampling at 4k with 400 samples to read... The AOs are triggered using buttons on the frontal (E-stim or M-Stim).. When the E-stim button is pushed it will generate a square-wave signal with the freq and pulse characteristics as selected on frontal panel (default is 1 pulse at 50Hz)... These are pulses are used to control a muscle stimulator... So the idea is to be able to send whatever signal I want and have the stimulator deliver that same stimulus to the muscle (e.g. 10 pulses at 50Hz, or 5 pulses at 100Hz, etc etc).. To check the timing of this, I connected the AO to the "trigger in" on the stimulator and the "trigger out" on the stimulator to an AI channel... The pulses are coming through from the stimulator as expected...
However, when I send the AO pulses labview seems to "freeze" or "suspend" until all output pulses are sent... This is very apparent with a high number of pulses (e.g. 10 pulses at 50Hz)... That is, the waveform chart freezes/stops scrolling until all AO signals are sent, then the chart updates all the pulses in one hit and continuous displaying data; rathe than have each pulse displayed individually...Why concern is that AI during the AO phase may be losted ot not sampled properly...
Can anyone provide me with an explanation for this behaviour? I am using a LV2010SP1 and a USB-6218 BNC multifuction DAQ.
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Attachments:
TMS2.vi ‏304 KB
TMS2.vi ‏304 KB

Hello Jack,
Reviewed the code.
Remember The way labview executes code, Labview executes code by flow of information meaning that it is going to wait untill the neccesary items are ready before executing the next part of the code.
For example If we want to make a simple add function for "x" and "y" labview is going to wait untill both inputs are ready for operation before operating and outputing "z" as a result.
It does it the same way everytime. I took the time and rearranged the code so we can understand it better, The execution happens from left to right, from top to bottom.
If we refer to the image, the arrows show us the flow of information of the VI, The DAQ assitant, the filtering of the signal and the Triggering is done before you actually output data through device1 analog output.
The code is expected to work that way cause it waits untill done acquiring with the DAQ asistant to start generating an output.
I can think of different options,
-You can modify this VI so that the output takes place regardless of the input data
-Having two different vis where you can set the read and write at different rates, using a functional global variable.
-Using a producer/consumer architecture.
This is an example that I think might be useful.
Using Producer/Consumer Architecture for DAQmx Read and Write to File
Hope this was helpful,
Luis Martinez.
Applications Engineer.
National Instruments.
Attachments:
Flow.JPG ‏146 KB

Labview absolute time waveform chart to excel

Hi everyone, I have a bit confusing on absolute time waveform chart. My problem is when I want to export to excel, the data duplicate nearly 30 times for each second. My project is about collect temperature from serial port and plot it in waveform chart, and I want to view history data in excel.
Anyone can help to solve my question? I attached my vi here..
Thank you so much..
Attachments:
NEW FINAL1.vi ‏96 KB
snap.PNG ‏11 KB

You are getting such a large number of readings because your VI has no timing control in it, if you simply add in a delay somewhere of maybe migrate to an event structure with a timeout then you can control the number of readings that are taken per second.

Legend for multiple waveform chart

I have a Waveform Chart (and legend) with multiple waveforms. I can control the visibility of a given waveform on the chart programmatically using the "ActPlot" and "Plot.Visible?" properties.
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Cheers,
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Dan
CLD

Hello DanB,
Following along the lines of what smercurio_fc suggested, you can use the Legend>Number Of Rows property (LegNumRows) to change the number of rows of your legend to the number of plots you are viewing, and then use the Plot>Plot Name property (Plot.Name) to edit the names of the plots yourself. I cannot see a property to extract these names dynamically, so this is probably your best bet.
I hope this helps, otherwise please do let us know if there is anything further,
Kind Regards,
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How do i set the time frame of a waveform chart programmatically to be a 30 sec window or a 24 hour window

i'm using LV7.0 and what i need to do is to be able to set the time frame or range of a waveform chart programmatically before i start taking and plotting data. sometimes this window needs to be 30s wide and sometimes it needs to be 24 hrs wide. (in the first reference, i need the chart to fill up with 30s of historical data then the whole chart scrolls with each new data point). the data acquisition records data at a rate of once per second. i've tried to use the chart properties of XScale.offset, XScale.Range.Minimum and XScale.Range.Maximum but no matter what i do the time-stamp on the x-axis is always "00:00:00 PM" and "MM/DD/YYYY" even though values are seen being plotted on the right side of the chart as expected.
Attachments:
BX0265 ShelfLife DAQmx.vi ‏120 KB

Okay, there seems to be some confusion here -- the X axis values are of type double, but they can be represented in the HH:MMS MMD:YYYY format if you want in which case it interprets the floating point as the number of seconds since 6pm Dec 31, 1903.
You can programmatically set this value using the XScale.Minimum and XScale.Maximum properties, but note that if you wire a waveform to the chart after setting these values the t0 parameter will override what you set using the property node for XScale.Minimum. If instead you leave the t0 parameter empty you can use the XScale.Offset property and wire the same value in that you wire to XScale.Minimum. Changing the amount you add to XScale.Minmum to obtain what you wire into XScale.Maximum will determine the time window size.
Doug M
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Want a constant time axis in waveform chart

hello,
my time axis in waveform chart is changing .how can i keep it constant say 1-100 .the whole point of this is to make waveform chart luk like a CRO.please need help.
thanks in advace
naveen.rabelli

I don't think what you're asking for is possible, due to the nature of the chart - it accepts Y values and inserts the X value automatically. Offhand, I can think of 3 solutions -
The bad one - constantly change the offset by moving it backwords. You will probably have flickering.
The workaround one - Paste a text box over the first number saying 1 and another over the second number saying 100.
The probably most correct one - Use a XY graph. Just have a 1D array of 100 elements and append it to a second 1D array with 1..100. Wire the 2D array into the graph terminal.
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Waveform chart number of clusters

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