Scalar to graph

I am running a while loop that takes a reading from an external analog channel. I want to plot this reading on a graph each time the loop runs. I thought this would be a simple matter but this doesn't seem to be the case. I've tried several methods without success, a few being:
- my reading (double) into "to dynamic data" control to a graph
- my reading into an "build array" control wired to a shift register on the While loop. I was unable to find a graph that would accept the data.
- bundle an the array from above with an array that contain a count of the loops, errors about mismatched data types or graphs that still wouldn't show the data.
Is there some method to take a scalar reading and get it into a graph?
CLD Certified

Of course, the Wavechart graph! Yes, that works perfectly. ::: Major slap to the forehead ::: I've been programming with Labview 8 for a few weeks now and got so immerse in the function screen that I complete forgot about the Control screen palette. And the searches never clued me in. Sorry to have bothered you guys with this post that has such an obvious answer....
CLD Certified

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SSRS 2008 R2 Column Graph, Scalar Axis, Columns Take more than 1 Category

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Here is a pastebin
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Whereas, I would expect something like this.

Hi clcrutch,
After testing the issue in my own environment, I can reproduce it. Just as you said, if there are two columns next to each other, then all the columns will be displayed on their own location; if all the columns in the chart exist space between each other, then
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Realtime graph of non-array scalar XY pairs

I am currently working with a VI that monitors temperature and I am trying
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Mitch-
Put the whole thing in a loop with a waveform chart inside the loop for
display. If you wire it to outside the loop it will automatically create an
array for it (e.g. for storage after the loop completed). Does that make
sense?
-David
Mitch wrote:
>
> I am currently working with a VI that monitors temperature and I am trying
> to feed XY pairs of time v. Temp to an XY graph. The problem seems to be
> that the graph will only accept arrayed numbers and I want to input the
> numbers realtime one pair at a time. Has anyone had any luck doing
> something like this...it is not in any of the books that I have.

How do I select more then one channel to view in tdms file viewer graph panel

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How do I make an XY-Graph plot points over time?

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Bundling and then using the Build Array is not correct. Yuo can see the correct method in the help for an XY Graph below. In order to use the normal XY Grpah, you would have two shif registers. One for the X array and one for the Y. Bundle the two arrays and then wire to the graph.
The other way is to use the Express XY Graph. With that, you can just wire your scalars to the X and Y inputs and set the Reset input to false.
Message Edited by Dennis Knutson on 11-12-2007 06:32 PM
Attachments:
XY Graph 1.PNG ‏21 KB
XY Graph 2.PNG ‏6 KB

What is the data type for the Data Dashboard XY Graph?

Hey all,
I am playing with the new Data Dashboard (!!) on my iPad 2 and am having trouble setting up the shared variables that host data to the XY Graph.
On my PC, in my Project (inside of a variable library) I have set up shared variables for all of the other controls/indicators available in the app; They all work great. However, I have not been able to identify the data type that is for the XY Graph in Data Dashboard. Of course, inside LabVIEW, I use a cluster of 2 arrays; this is not an available data type that I can select while creating a new variable on the hosting side. I have even gone so far as to create a custom control from my XYGraph in LabVIEW and then creating the data type "From Custom Control..." with no success.
What gives? Am I missing something obvious? Thanks for the help!!
Tom
Solved!
Go to Solution.

Great question, Aerogoob.
The XY graph can be bound to a 1d array of "points", where each point is a cluster of two numerics (X and Y). To create a shared variable of this type, you can set the data type to "From Custom Control..." in the shared variable properties dialog. Of course, first you'll have to build the custom control of the correct type: array of cluster of two numerics.
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Multiple plots in Express XY graph

Hello,
I'm trying to have several plots in an Express XY graph and use it without clearing data on each call - like a chart.
On the Y Input, I'm inserting an array with 2 values (1 for each plot) and in the convert to dinamic data I choose 1D array of scalars - multiple channels. The problem is that there's only one plot in the graph.
See attached example test.vi
Can anyone help?
Thanks.
Attachments:
XYtest.vi ‏117 KB

Hi Paulo
You need as many x arrays of values as y arrays of values.
See attached doc
Cheers
Alipio
"Qod natura non dat, Salmantica non praestat"
Attachments:
XYpairs.doc ‏46 KB

Most efficient way to extract the amplitude of a signal and display on an intensity graph

Hi All,
I am having difficulty to display the amplitude of an voltage signal (voltage picked up by NI DAQ card).
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Charlie

Hi Hillary,
Thanks for your reply.
Yes, I did tried to use Amplitude and Levels Express vi, it should be the one I am looking for, but I found it not work in my case, I need to put the value of amplitudes into a 2D array.
If I use Amplitude and Levels Express vi, it will give me a 3D array, I have found the solution, just convert the dynamic data to single scalar. (see pic attached)
Anybody can help me to solve the following 2 problems:
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Charts and graph shown as --array and cluster datatype in block diagram

Hi friends,
I new user...
I have a basic doubt...
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These are very basic issues and it should be clear once you study the online help and examples for a while.
Waveform Graphs
Plain waveform graphs assume equally spaced data. The x-values are implicit from x0 and dx of the x-axis. By default x0=0 and dx=1, meaning the x-values are the array indices. You can change the offset and multiplier from the properties dialog or programmatically via property nodes.
If you give a 2D array, there will be multiple graphs. Transpose if needed.
Alternatively, you can give a cluster of [x0, dx, y-array] and the x-axis will adjust accordingly.
As another alternative, you can built a waveform datatype and feed it to the graph.
You can also graph dynamic data.
XY graphs
xy graphs are needed if the x-vlaues are not regularly spaced.They take a variety of data formats, so pick what is most approriate for the data
A cluster of an x-array and a y-array
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A complex datatype (it will graph imaginary vs. real or similar).
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Charts are different, because they maintain a data history buffer an retain a certain amount of data. Some examples of data inputs:
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An array: The array data will be appended to the existing chart data.
A cluster of e.g. 5 points: The chart will have 5 dividual plots, one point gets appended to each plot.
etc.
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LabVIEW Champion . Do more with less code and in less time .

Variable, Multi-plot XY Graph?

Hey all, first text to the forums so here goes:
The issue I have deals with processing data from a number of strain gages. My goal is to do the following:
- At the press of a button ("Push to Snapshot XY Points"), I need to collect a "snapshot" of the strain data that is continuously flowing out of the DAQ Assistant
- This strain data is currently being pulled from DDT and converted to a 2D array "Collected Data", which holds the current value of each channel in its own row.
- I want to take each individual channel of this information and pair its "collected data snapshot" value with the current Load Case (a double value I control), creating an (x,y) coordinate pair for each channel (all channels will be assigned the same "Load Case")
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I currently have some code that takes the "Collected Data" Array, and moved it through a FOR loop setup with auto indexing enabled (I imagine I will need some sort of smart FOR loop to handle the variation in channel count). From here I am having trouble organizing the data into the correct arrays/clusters such that I can store and plot it. Any help would be much appreciated, thanks!
To Note: LabVIEW 2014, Windows, cDAQ Hardware
Desired Output Graph:
Current Code:
Current Front Panel View of Arrays Being Built:

Without getting too hung up with the correctness of what you're doing (or what I did for that matter), attached is a VI that should do what (I think) you're asking. The values get appended to the storage arrays and those get forward to the start of the next loop iteration via the shift registers. The transpose array functions are there soley so that I could use auto indexing on the FOR loop when creating the 1D array of clusters for the XY graph.
couple points about your code:
1] set you "from DDT" signal conversion to 1D array of scalars so you don't have to auto index and then index array inside the FOR loop. The data is 1D already.
2] inside your FOR loop you create a cluster and then convert from cluster to array. Use a single "build array" instead.
Attachments:
display_XY.vi ‏101 KB

XY-Graph TORQUE AND POWER IN FUCNTION OF ROTATE SPEED

Dear,
I have made a program in Labview for my endwork so i have now one problem ; i read data (torque,temperature,power,speed of an engine with an USB-6009 daq-kaart.) now i want to make a graph of the torque (koppel in dutch) in funtion of rotate speed and also power(vermogen in dutch). i have used xy graph but i get nothing . What do i wrong can some one help me? I send the program also as attachement ; on the y i will torque(=koppel) and x i will rotate speed (toerental)
thank you
Attachments:
Eindwerk_data.vi ‏346 KB

Hey Drayton,
Please have a look at the attached VI.
Left
of the While Loop I created a 2 dimensional array. Column zero is
representing the RPM, column 1 the Torque (koppel) and column 2 is the
Power (vermogen).
Then I am simulating the measured data of RMP,
Torque and Power. As I would like to limit the number of elements in
the array, I used the "Remainder and Quotient" function to round to a
nearest lower multiple of 20. This means you will have steps of 20 RPM
in your graph. The lenght of the array is in the case: 4000 RMP max /
20 = 200 elements. Of course you can change this but then also your
array size will become larger (more processor time needed to analyze).
Next
step is to get the index number in the existing array which equals the
current measured RPM. This index is needed to replace the
corresponding torque and power values in the array.
If the newest
torque or power value is greater than the already available value for
the corresponding RPM, then this value will overwrite the existing
value. If not, then the existing torque and power value will be kept.
Finally I will extract the complete columns of the array for RPM, torque and power to apply them to the XY graph.
You can almost copy/paste this into your VI.
As
your data is coming from Express VI, the wires contain waveform data
which also inclused timestamp information. As you cannot use waveform
data with arrays and actually don't need it, you have to use the
function "From DDT". This is also an express VI to convert the Dynamic
Data Type from the Express VI into a scalar datatype. You can show to
analyze only one point at a time of by using an array.
I have also seen that you have place additional numeric indicators on your front panel beside the meters.
This is great. You only used an additional object to do so causing also an additional terminal appearing on your block diagram.
Actually,
the numeric front panel objects have already an numeric indicator
related to it. This way no additional block diagram terminal will show
up.
You only need to enable it.
Right click on the object to open
the shortcut menu ---> Visible Items --> Numeric Display. There
is your numeric indicator directly related to the object.
If you do this for all you front panel objects, your block diagram will look much nicer and easier to read.
Best regards,
Joeri
National Instruments
Applications Engineering
http://www.ni.com/ask
Make our forums great:
If you like the answer, don't forget to "Kudos!".
"Accept the Solution" if your question is answered!
Attachments:
Arrays.vi ‏18 KB

Multiple XY graph

Hi, in a control and simulation loop, I am making an xy graph that combines data from two wires for the x values and data from two wires for the y values. I have attached a picture of part of the code. When I run using some variable it works ok (picture 1) but when I change the variable to a lower value it looks like the signal stopped and the rest of the curve is not drawn (picture 2, green line which should go until about 42 in the x axis). Am I inserting the right functions for making this sort of graphs or am I missing something like a build array function or something similar?
Thanks
Attachments:
XY graph.JPG ‏26 KB
Picture 1.JPG ‏41 KB
Picture 2.JPG ‏41 KB

For the untrained eye it is impossible to tell what you really want and what the significant difference between the two images is. On both graphs that you show, the green curve does not go to 42 on the x-axis. (one goes to x=~12 and the other to x=~15)
Maybe you should have a look at the real data. Could it be some values are NaN? I don't have this particular toolkit (simulation?) installed, but if you attach your program, somebody else might be able to troubleshoot further.
I am not a big fan of dynamic data and expres VIs, because they hide too much information when looking at a diagram picture. What is in the arrays and scalars that build the dynamic data? Is the express VI set to retain data between calls?
LabVIEW Champion . Do more with less code and in less time .

Ploting 2 Scalar Numbers at The Time

Hi Everyone,
I have a main and a sub-vi to plot 2 scalar numbers at the time using the graph control (LV8.5), and is not working correctly as I will expect to work. Basically the main vi has a graph that is updated everytime its sub-vi is called. However it looks like the shift registers keep "its memory" alive even though the sub-vi has finished or stopped.
At the sub-vi level, I don't reset the shift registers because I don't want this operation to happen everytime this sub-vi is called. I was hoping that Labview will reset the shift registers every time that the main vi has finished and re-started again.
Could someone suggest a different technique to make this vi work?
Basically, the main vi calls its sub-vi 10 times and updates its graph properly. However the main graph keeps plotting more than 10 numbers. . .
I know that I could use a chart and fix this issue but I would like to use a graph control if possible.
Thanks,
Frank
Attachments:
ChartingTwoNumbersAtTheTime_SUB_VI.vi ‏15 KB
ChartingTwoNumbersAtTheTime.JPG ‏83 KB
ChartingTwoNumbersAtTheTimeMainVI.vi ‏15 KB

Since you are using LabVIEW 8.5, you can use feedback nodes in the subVI without the need for any while loop. Now use a case structure connected to the "first call?" primitive as e.g. in the attached modification.
You should not place a wait in the subVI, this make no sense. There is no reason for the sequence frame. You also don't need to zero the graph in the main VI as you currently do.
LabVIEW Champion . Do more with less code and in less time .
Attachments:
ChartingTwoNumbersAtTheTime_SUB_VIMOD.vi ‏15 KB
ChartingTwoNumbersAtTheTimeMainVIMOD.vi ‏14 KB

How to graph the counter frequency

Hello, does anyone know how to make a graph from a frequency signal that comes from a counter?
It seems that I first need to convert the frequency signal (scalar) into a waveform type.
I do not know how do this. Any suggestions for me?
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Thanks,
Peter

Peter,
I can't look at the example you mentioned from the PC I'm at now, but I can describe the way I've always done it.
I'm assuming that the incoming frequency varies, and is calculated by timestamping the incoming edges. This would mean that the hardware is doing something like period measurement and the sample rate varies with the varying periods. Such data wouldn't be suitable for the waveform datatype which assumes a constant interval time dt.
I would recommend graphing on an XY Graph. The Y data is your frequency array. The X (time) data is derived from it pretty simply. First send your frequency array through a 1/x function block to create an array of individual interval times. Then perform a cumulative sum of the interval array to produce a Time array for your X axis.
The cumulative sum can be obtained with a For loop with a single shift register initialized to 0. Auto-index the loop with the interval array. Sum each element with the left-hand shift register value. Send the sum to both the right-hand shift register and to an auto-indexed output for cumulative time.
-Kevin P.

Multiple AIs on separate graph

Hello,
I am acquiring data from several accelerometers (10 Analog Inputs channels) at the same time upon the trigger of a digital rising edge input. I was wondering how to separate each channel or plot each channel on separate graph.
regards
don
Solved!
Go to Solution.

Hi DAQ_Newbie,
If you are using Express VIs, your acquired signals would be Dynamic Data (blue-white stripes). You can separate each channel by using Split Signals.
If you are using DAQmx VIs, your acquired signals can be scalar (thin lines), arrays (thicker lines) or waveform (brown-white stripes). You can separate each channel by using Index Array.
After separating the channels, you can plot each of the channel to the different graph.
Hope that helps,
Sincerely,
Krisna Wisnu
Message Edited by Krisna Wisnu on 10-11-2008 12:46 PM
Sincerely,
Krisna Wisnu

Scalar to graph

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