Multiple Axis Waveform Chart History?

Hello Everyone,
Recently I have been working on increasing my capabilities with waveform charts. I am plotting 3 signals on 3 seperate axis. I'd like to be able to transfer the plot history from one chart to another via property nodes. The problem is, only 2 of my signals are making it through, and I'm not sure why.
For a little background why my code is structured the way it is, I followed an example from here:
Pausing Charts
Basically I want to be able to zoom in on the chart while the program is running. By hitting pause, the data is transfered to another plot that isn't being updated. Again, only 2 of my signals are making it through, and I'm not sure if there is a property node I'm missing.
Any help would be appreciated, the VI is attached below.
Thanks,
Alex
Attachments:
Chart Test.vi ‏39 KB

For some reason the "Brake Temp" plot's color was screwed up. If you look at the legend it looks like it's black. However, changing the plot's color doesn't seem to have any effect. If you just recreate the "pause" graph by copying the "Waveform Chart" indicator then it will work.
Suggestion: look into the Event Structure.

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Clear waveform chart history if dynamic 1D data is used

I am new to Labview and am using a Waveform Chart. To clear this I need to supply an empty array. I have done this with scalar inputs, but in this present case, the input to the chart is a bundle of 1-D array of dynamic data. I cannot figure out how to create a suitable empty array of type 1D array of dynamic data to initialize the plot (wire to the History).
It seems like there should be a better (easier) way of clearing the plot...
Thanks for any ideas.
Solved!
Go to Solution.

Hi rockybooth,
right click on the connector to the history property and select "create constant". You should get what you need.
Hope it helps.
Mike

Accessing waveform chart history collected via DAQmx

Hello, I'm collecting voltage data using DAQmx and I'm displaying the data using a waveform chart. At the end of the acquisition I would like to access the entire data set stored in the chart but when I attempt to do so using a History Data property node, it only gives me the data that was collected in the last chart update, not all of the data stored in the chart. Attached is a copy of the program, which is simply the Continuous Analog Input example. Any suggestions? Thanks!
Attachments:
Jeffs_Voltage - Continuous Input.vi ‏80 KB

Data Flow. You have no clue when that chart history will be read. You need to force it to read after the acquisition is complete. Using the error wire to force the data dependancy is a good way to do it.
How long are you acquiring the data for? If much more than a few seconds, I would use that logging feature to stream the data to a TDMS file and then you can just read the resulting file.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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Synchronize reset of multiple waveform charts

My main VI has multiple sweeping waveform chart, base off the Continuous Measurement and Logging template. I want to be able to change x axis range (toggling between 10 seconds of data and 3 seconds of data)
I did it by changing the X scale range min to zero and max to the appropiate sample size, and clear the history. While this works for each chart they always ended up off sync instead.
At first I thought that's because I put it in a ub VI. But moving everything to te main vi does not change the behavior.
Any ideas? Thanks.
Solved!
Go to Solution.

Well those all have to run sequentially in the UI thread so there is no way to do them "Simultaineuosly" HOWEVER, if you bookend those property nodes with an Involk of the method Defer FP Updates (True then False) you'll see much more what you expect.
Tighter alignment of the "Clear Histoys" would also be done by splitting up your p-nodes so do all of them at first then change all the scales.
Jeff

Saving array data from a waveform chart

I am using a CRIO 9004 and a 9237 bridge module to measure some strains from strain gauges. I've got one timed loop that reads the DMA FIFO and puts the arrays of values (16 data points, 4 per channel) into a queue. In the consumer timed loop a For loop scales the binary data, auto indexes it into arrays, then the arrays are merged into a 2D array for the four channels displayed on a waveform chart . Everytime the consumer loop runs it indexes 4 data points (per channel) yet the waveform chart plots them in a consecutive manner and doesn't overwrite the previous four. If I convert the arrays to waveform arrays I don't see anything on the waveform chart.
If I pass the 2D array of data to a array indicator inside or outside the consumer loop I get only 16 data points. I want to save the information that appears on the waveform chart after the consumer loop but because I'm not using waveform data type I can't use the write waveforms to file vi. The waveform chart history buffer has been set to 195360.
Idealy we will run the four channels for 120 seconds charting the data and saving the data. The minimum data rate is 1613kS/s (403 per channel) The data can be saved after the loops have finished gathering and processing or while they are running. I noticed when I tried to write to TDMS it slowed the consumer down. Same thing if I use a shift register with the volume of data.
I suspect I'm not sending data to the chart in the correct manner ( usualy takes two attempts to "clear chart" using shortcut menu). I'm not too familiar with timed loops /producer consumer loops and just tried to put something together based on examples.
I've attached my host vi and front panel screenshot.

Hope they appear attached this time.
Attachments:
Basic DMA (Host).vi ‏444 KB
screenshot2.jpg ‏113 KB

Plotting data with multiple y-axis using waveform chart

I am using LabVIEW 7.1 and am simply trying to split my data on one waveform chart using 2 Y axis. One goes from 0-150 and the other from 800-1000. I want them to graph on the same chart, and I have selected 'duplicate scale' when I right click on the chart, as instructed in the labview manual, but both of my data streams are still only connected to one of my axis. I can't get it to recognize that one data stream should go on one axis and the other stream should go on the other axis. Can someone help please?

Right-click in the plot legend one plot. In the context menu select y-axis and after the axis you want for this plot. The scale is changed directly.
There is an image of the context menu attached.
I hope this helps
Greetings
shb
Attachments:
two y-axis.png ‏16 KB

Waveform chart X-Axis reverses itself when upper limit is edited in Absolute Time - problem may be linked to Timestamp Control?

I've seen this problem for some time now, and it still exists in the Silver toolset Waveform Chart in LV 2012. If the chart is in strip mode, and you edit the upper limit value to a point in the future, the X-Axis will invert (higher values/ later time to the left), to the limit of the Chart History length. This happens whether the chart is active (logging data on a compiled executable) or even when in design mode, though it's more consistent when there's data in the chart. It's not history length related as far as I can tell, as I set the length to 7 days of sampling @ 1-second intervals (605K), and it happens when I try to set the end time to an hour in the future with only a few minutes of data collected - suddenly the right Absolute Time becomes the time my last sample point was collected, while the left Absolute Time becomes nearly 7 days in the future (so neither end point is what I was setting it to).
It's nice that the chart gives the option of editing the limits, but as such, it's important that they work as you would expect them to.
Also - until this is addressed, is there a way to lock it against editing? Until a fix is made, my workaround is to put a transparent button over the range start & end points, and a transparent flat rectangle above all other mid-range points, and pop-up a data entry form with a Timestamp control to allow editing. Unfortunately, this doesn't work as I would expect, as typing "11 AM" in the Timestamp control over a prior value of say "10:05:34.232 AM" ends up becoming "11:05:34.232 AM" instead. ??? Another error - or is this by design? If it's by design, is there an option to make it behave as I would prefer (11 AM = 11:00:00.000 AM), as Excel behaves with timestamps? I can't help but suspect this may be linked to the chart axis issue.
Also - I just built a simplified chart modeled somewhat on my current project, and could not get this to recur. BUT... had the strangest thing happen: My sample data was generated using the Trig functions for Sine and Cosine, and at one point my waveforms distorted on the display, so I'm attaching that here plus the simplified chart project.
Last - my system is LV 2012 on Win7 Pro-x64.
Thanks!
Erik
Attachments:
Chart data distorted.png ‏45 KB
Waveform Chart Flaw.zip ‏17 KB

I am not so sure that this is a bug, and I have not been able to reproduce this behavior that you are describing.
But you can lock it from editing by right-clicking on the graph and go to Properties>>Appearance>>Enabled State --> Disabled
Also, word of advice for the future: You will get more replies from the community with shorter posts and keeping it to one question per post. Summarize what the issue is, and put the detailed documentation and instructions to reproduce in the actual VI.
Huntington W
National Instruments
Applications Engineer
***Don't forget to give Kudos and Accepted as Solution where it is deserved***

Waveform chart time axis is not matching the waveform data

So here an interesting conundrum I hope you might be able to help me with...
My VI has waveform data sent to a chart, though the data is not being plotted against the current time. Rather, it is being plotted starting way back in the reference time (way back in 1903). I don't understand why this is happening. When I build the waveform, I use the "Get Date/Time in Seconds" function outside the while loop and feed that into my "Build Waveform" Function as the t0 value. My dt value is 0.05 (20 Hz) and then I feed in my array of data in the Y input. Any ideas why the chart is plotting this data over 100 years ago? Thanks!
Andrew

Hiii, Ronin
Here is your solution.
By default, waveform charts and graphs display the absolute time at time 0 as 7:00:00 PM, 12/31/1903 on a Windows based system. Property nodes can be used to get the correct absolute time to display on the x-axis of the waveform chart.
First, right click the chart on the front panel and select X Scale >> Formatting. Then set the format to Absolute Time.
Create a property node for the waveform chart by right-clicking on the chart on the block diagram and selecting Create >> Property Node. Expand the property node to display two properties. Select the Format property and the Offset property. The Format property is located under X-Scale >> Format and Precision >> Format, and the Offset property can be found under X-Scale >> Offset and Multiplier >> Offset. Right click on the property node and select Change All to Write.
For the Format property, the context help shows that there are multiple inputs to this property. Wire in a value of 7 to set the format to Time and Date.For the Offset property, first wire the output of the Get Data/Time in Seconds VI to the input of the To Double Precision Float VI. Then wire the output of the To Double Precision Float VI to the Offset property.
In addition, if you know the number of data points plotted to the chart per second, you can set the Multiplier property located under X-Scale >> Offset and Multiplier >> Multiplier. If there are x data points generated per second, wire in a value of 1/x to the Multiplier property. A simple example program "Chart with Timestamp" that demonstrates how to do that is attached.
Thanks,
Nishant
Attachments:
Chart with Timestamp.vi ‏36 KB

Waveform chart x-axis in time (secs)

Ok here's what I'm trying to achieve (unsuccessfully at the moment). I've got a 2D array of data collected from a sensor. Each column in the array corresponds to one of the sensor's axes. I want to display 3 columns of data on a waveform chart with the magnitude of the data as the Y axis and time as the Z axis.
Here's the tricky bit. I have no timestamp with the data. However, I'm taking the first element of data in each column as being T (time) = 0. The sampling rate of the sensor is 100Hz so => dt = 0.01. So each data element in each column (sample) is separated by 0.01 seconds. Therefore by knowing the number of samples in a column of the array, I can get the end time. E.G. 1000 elements in one column of the array => end time, T = 1000 * 0.01 = 10 seconds.
So in the above example the chart's time axis should go from t = 00:00:00 to t = 00:00:10. However I'm not gettin anything like this in my chart. I did up a quick vi showing what I'm currently doin.
Any tips?
Attachments:
2D waveform chart.vi ‏32 KB

I've re-attached my example vi with a minor adjustment highlighting the problem. Each column of the array now contains 2000 elements which exceeds the deafult chart history buffer length value of 1024. This causes problems with the time display on the chart. I could of course change the chart history buffer length manually by right clicking etc. but would need to do it in real time in my actual vi as I won't know the size of the array until execution.
Is that clearer?
Running the vi now should show you, the time starts at 00:00:09 instead of 00:00:00. I understand why but not how to fix it...

Change labels of multiple axis in xy-chart

Hi,
I want to programmatically change the labels of the axes in a xy-chart with two y-axes.
I can easily manage this for the x-axis and the first y-axis. But I can't find how to access the properties of the second y-axis. How to do this?
Steven
LV 7.1 - 8.2

There is a property named "Active Y Scale".
In dictates which of the multiple axis you are going to act on.
Set it to the index of the axis you want to change BEFORE setting the label.
Ben
Ben Rayner
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How to get the history(datapoints) of 32 waveform-charts which are in one cluster?

Thanks in advance. I would like to handle up to 32 waveform-charts by using a cluster. My problem is that the datapoints of their history has to be saved if a particular event occures. How can I get the character-node for the history of a waveform-chart inside the cluster?

I'm not certain what you are asking, but here's a suggestion. On the front panel, you can pop-up (right-click) on a waveform chart within a cluster and create a property-node (for the history), which can be manipulated as you desire on the diagram.

Plotting multiple graphs on one waveform chart with dynamic data types

I'm trying to put multiple graphs on one waveform chart and having data agreement errors. I'm wondering if it has anything to do with the fact that dynamic data is being used (I've had no problems with other datatypes in the past). Does anyone know how to correct this problem? I've attached the following .VI. There will be plenty of .VIs on the bottom that won't load, but they are not consequential for this problem.
Thanks!
Brian
Solved!
Go to Solution.
Attachments:
Stiffness Control V1.vi ‏119 KB

you could use stacked plots by right clicking on the chart and clicking on the stacked plots and than on the front panek you can put a bundle function on the FP and hook your signals up
Harold Timmis
[email protected]
Orlando,Fl
*Kudos always welcome
Attachments:
multiplotwaveform.JPG ‏138 KB

Why does AI Read(Asynchronous).vi cause the waveform chart to not display any history ?

I trying to create a strip chart for 16 channels that will require displaying 10-20 minutes of data.It also starts a separate vi to set gains and offsets while displaying the data. Using AI Read.vi uses 100% of the CPU so the second vi does not run. But using AI Read (async).vi allows the second vi to run, but causes the waveform chart to not display the history? I'm using LabView version 6.0.2.

Hi Waynes World,
I have a couple of questions that may help us solve this issue...
1) If you are modifying one of our example programs, which one did you start with?
2) What kind of analog input are you doing? Buffered? Finite or continuous?
3) Have you tried increasing the buffer size of the strip chart? This will allow the chart to store more data in it.
4) When you use the Async VI, and when you are using the other, can you describe how the strip chart is showing the data... does the data in the chart keep growing and growing... or does it clear itself and start over when the pine reaches the end?
I think this issue is rooted in how the buffer is being used with the two different AI Reads and how it returns data to the chart.
On a side note, have you considered upgrading to a newer version of LabVIEW? Our latest versions of LabVIEW come with many new features and it is signifigantly easier to use.

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.
Is it possible to programmatically make the legend only contain the plot names that are visible at any given time?
Cheers,
Dan
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,
Michael S.
Applications Engineer
NI UK & Ireland

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.
Try to take over the world!

Multiple Axis Waveform Chart History?

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