Waveform graph Y positions

I am trying to view 2 channels on a TDS5034B oscilloscope at different vertical positions. Using the driver files, i can adjust the channels vertical positions on the scope but not on my waveform graph. They both start on the 0 position intsead on my required 1 and -2 so that they can be viewed easier. Does the build wavefrom need extra info?

When you retrieve the waveform data from the scope, you are getting the actual x values and not the display offset. There are a couple of things that you can do. One is to retrieve the display offset and add that to the data. This is easily done with the add function. One input would be your x array. The other input would be the offset as a scalar. This will off the offset to every element in the array. Of course when you do that, any measurements you do with the resultant waveform will have to take into account the offset that you added. Another way to offset the waveforms and keep the original values is to assign the waveforms to two different axes of a graph (duplicate scales) and then offset the scales. For example, you could use a property node to set y range 1 to +7/-3 and y range 2 to +3/-7 if the range would normally be +5/-5. This is basically what you are doing on the scope when you move the zero reference point.

Similar Messages

Cursor name position in Waveform Graph

I lost the cursor name in the waveform graph, after programmed the cursor positions.
I enabled 3 cursors, shown the cursor names, and programmed their positions in my VI. After running the VI, all cursor names are gone. I believe they are moved to somewhere out of the plot range due to LV malfunction. I cut and copy the graph to the VI attached, and enabled a new cursor, which looks good.
I need to get the lost cursor names back (manually is OK). I also want to know how to avoid this.
I am using LV 7.1 under Win XP Pro.
Attachments:
Study_Missing Cursor Name.vi ‏71 KB

I have created a test vi that could generate this problem. I generated a waveform graph and label each peak with cursor name. Then I copied the waveform graph and paste to form another waveform graph 2 in which the cursor name is gone even the show cursor name is still enable. I have not been able to find the cursor names from the waveform graph 2.
I am using labview 7.0
HMP
Attachments:
test.vi ‏60 KB

Moving cursor to Zoomed Position in waveform graph

Hello
I have 2 cursors in my waveform graph and I would like to have the cursors move to the zoomed in position of the graph when I zoom in or out of the graph. Could some please tell me how to do it. Thankyou in advance
Regards
Pratheek
Solved!
Go to Solution.
Attachments:
Failure Device.vi ‏89 KB

HI Mike
Thanks for the reply. When I apply the logic to reposition the cursor in the scale range event only one cursor is moving to the zoomed in position. The other cursor remains out of graph scale. I tried to repeat the same logc but it didn't work. Could you please tell me how to get the 2nd cursor also in to the scale range. Sorry i'm fairly new to labview. I have attached the pic of what I tried. Thankyou in advance
Regards
Pratheek
Attachments:
Capture.PNG ‏18 KB

How can I get the cursor value from a waveform graph

Is there a way to get the value of cursor position on the waveform graph so mathematical calculations be performed on those values. We can see the value in cursor legend, but can we extract those values for future calculations in the block diagram somehow.

Right-click on the waveform graph icon. Select Create>Property Node>Cursor>Cursor Position. That spits out a a xy cluster for the current cursor position.
If you have more than one cursor, you can either set up a loop and set the Active Cursor property node (right click the property node and select "Change to Write") or you can pull everything you ever wanted to know about every cursor with the Cursor List property node.

How do I Get the value from a mouse click - on a waveform graph?

If I have made a plot into a Waveform Graph and later want to do a zoom of my data
(Not zoom into the Waveform Graph, but regenerate the data). How do I read the mouse
coordinate if I click on the graph window. I know how to put up the horiz and vert
cursors but don't know how to just read the mouse click. I would really like to
follow the windows standard that identifys a rectangle by clicking and draging and then
be able to read the corners of the rectangle. Thanks, Rick
PS: Using Labview 6i

I would recommend to 'translate' your graph in a picture and dislay it in a picture control (see picture examples in LV6).
Once you did it, pictures have an extremely useful property called Mouse that returns the mouse coordinates and click events when you place the cursor on the picture.
By this you can re-arrange the graph on picture appearance.
There are also other methods such as using a Window's API that returns the mouse position referred to the whole screen window, but I believe this would be much more difficult to implement.
Let me know if this was clear and if you need an example vi.
Good luck,
Alberto

Transition measurement vi cursors displayed in waveform graph are moving outside of scale

Using a waveform graph to display pressure over time. I wanted to be able to calculate the fall time of the pressure over time so I'm using the Transition Measurement vi. I copied exactly what was in the example for transition measurement inside help and it is correctly determining the falling transition time but I am having a problem with the cursors on the waveform graph. I should be seeing a set of green vertical cursors marking out the fall start time and fall end time like in the picture I've attached (capture2) like in the example. The problem is they both always start at 3.43 (capture1) and after each sample period they increment by one (4.34, 5.34, 6.34) The come right out of the bundle from the transition measurement output as those numbers. The period of the signal I'm interested in is always less than 2 seconds, so I never see the vertical cursors.
I've tried substituting my daq signal with a sine wave generator and it does the same thing.
The block diagram is in the first capture
also I would be interested in finding out exactly how the numbers wired to the active cursor property of the property node for a waveform graph relate back to the actual cursors on the graph. Are they just automatically numbered starting with 0 from the top-down?
Wayland
Solved!
Go to Solution.
Attachments:
Capture.PNG ‏44 KB
Capture1.PNG ‏7 KB
Capture2.PNG ‏29 KB

Hi Wayland,
The reason the cursors are always apparent in the example VI for the Transition Measurement.vi, is because the signal being generated is always resetting. So, the signal resets to a 'new' signal for the cursors to go over and therefore always remain in the somewhat same location. The Waveform Graph is also configured in such a way that it will not move or continue to show new data coming in, the data cursors have moved onto. So in your case, you will want to right click the graph and make sure "Ignore Time Stamp" is not checked/selected. This will make it so the graph keeps up with your incoming data and the cursors. You can check this in the example file by removing the True Constant going to the waveform generator and changing the time stamp option previously mentioned.
In order to view the available cursors and their numbered position, you can right click on the Waveform Graph and select properties. In the properties window there is a Cursors tab, inside this tab at the top is a drop down menu that lists all of available cursors, indexed starting with 0 at the top.
-Jake B.

Has anyone "zoomed in" on a portion of a waveform graph?

Has anyone ever used two cursors to zoom in on a portion of a waveform graph?
I've seen that newer Oscilloscopes offer features to do this both horizontally and vertically.
See the attached jpg for an example of what I'm trying to do. It is from Google Finance. Notice the area circled in red. The two cursors define the portion of the waveform to be displayed on the main graph. There is also a scrollbar beneath them which allows the user to quickly move the zoomed-in area across the graph- I would love to have that functionality on the LabVIEW graphs.
My first thought is that I can do this using mostly property nodes. Not sure on vertical zooming scrolling the horizontal zoom- I'm thinking maybe this would best be done using scrollbars which are not part of the graph itself.
Any ideas or comments?
Thanks,
Dave
Attachments:
deleteme.jpg ‏38 KB

Cursor position is available in Labview via a property node. You can also set about every chart property with property nodes. I have used this many times. Here is a trick. If you have two cursors, Make separate arrays of the x and y positions. Then use the "Array max&min" to sort them. This will make your program independent of the cursor sequence.
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)

How do I change the width of the x-scrollbar for a waveform graph?

I have a LV7.1 application that contains a waveform graph and must be usable on several PC with widely varying screen resolutions. I have decided to position and scale the front panel objects programatically, including the graph itself. The appearance of the graph is satisfactory on all screens, except for the x-scrollbar. The width of the x-scrollbar does not change when I change the size of the graph. I cannot figure out how to change the width of the scrollbar programatically to match the adjusted size of the graph. Any suggestions?
Regards,
Chris

Chris,
I don't think that you can change the width of the x axis scroll bar programatically. One thing you could do though is create your own scrollbar and change it's properties as your program runs. I wrote a quick example of how you could do this and I've attached it to this thread.
I hope this helps,
Justin D.
Applications Engineer
National Instruments
Attachments:
ChangeXScrollbar.vi ‏116 KB

Center the cursor on the Waveform Graph?

I have a waveform graph where the user can adjust the scale on both the X and Y axes. The "problem" that I am having is that if the scale's range is set too far from where the cursor is at, the cursor will be off screen and not selectable. So, I am trying to center the cursor to the scale when the scale is changed or via a button. Here is the code that I have written for one of the Cursor plots:
Select Case setBlueCursor
Case 1
blueCursorPt.Plot = plotInlineTorque
inlineTorqueMax = yAxisInlineTorque.Range.Maximum
inlineTorqueMin = yAxisInlineTorque.Range.Minimum
blueCursorStartY = (inlineTorqueMax + inlineTorqueMin) / 2
blueCursorStartX = (XAxis.Range.Maximum + XAxis.Range.Minimum) / 2
blueCursorPt.YPosition = blueCursorStartY
blueCursorPt.XPosition = blueCursorStartX
This code will center the cursor like I want but then I can't move the cursor after that as it is "stuck" at the position that I have coded it. The problem appears to be with the last two lines of code here. I do not know of any other way to do this though. I have tried the "moveCursor" method but the end result ends the same way, with the cursor stuck in the center and can't move. Any help on a solution? Is there a better, easier way to do this? I'm new to Measurement Studio and .NET.
Thank you

This code works. It appears that I was calling the subroutine that this code is located in over and over in another part of my program.

How does waveform graph downsamples the data before it is plotted

Hi,
I'm interested in how does waveform graph downsamples the data before it is plotted and what algorithm is used for this purpose? My goal is to plot 30 plots that have 1M samples each and I would like to downsample them before plotting onto a graph. I tried several VIs/algorithms for resampling and none of them gave the same result as seen by waveform graph (when all the samples are plotted).
For example, if only one sample of 1M samples is 1 and all others are 0, then after downsampling to 1k samples the sample is not visible on the graph anymore. However, if I plot all 1M samples directly onto the graph, then also this 1 sample is visible (see attached example).
Solved!
Go to Solution.
Attachments:
WFGDownsampling.vi ‏19 KB

Hi andrej,
LabVIEW draws plots in the way that draw every pixel affected by signal. So for example if there is zero-valued 1M samples and even one equals to 1, you will see the peak. That is the reason why you do not get the exactly same behavior comparing to interpolating. But if you set FIR as interpolation mode in Resample Waveforms (single shot).vi, result is really similar, but of course amplitude is 1000-times smaller than original one (because there is dt set to 1000). Keep also in mind that in Graph 2, there is different Y-scale and it should be considered as noise, not relevant data, I would expect 1000-times smaller amplitude as in Graph 3, it is many more times smaller.
I would also like to say something about downsampling (decimating) the data. If you have 1M samples, you can see the peak even that there is only one value. But bigger problem is that with this graph resolution (I guess that is not more than 1000px), it is problem to find position of this peak. It means that still the zoom is needed to know where the peak is. Usually, when there is that big set of data, you are extracting different data (statistical information, peaks in FFT, etc.) not just visual data in graph.
Mariaaa:
I do not understand your question, can you please describe more your needs? You mentioned saving the data into a file, you can use Write to Measurement File express VI or see Write to Text File.vi in Example Finder and try to appropriately modify it.
Best regards,
Martin

Dispaying a waveform graph with control of the cursor in the document.

I would like to be able to control the cursor when I save my waveform graph in html. I'm currently saving the graph through the report vi's

I am not sure I understand your question. Do you want to simply control where the cursor is on the picture you are appending to the html report. If so then when you use the Append Control Image to Report VI it basically takes a snap shot at that moment and displays it. Therefore you just need to place the cursor where you wnat it before you add the image.
To programttically control the cursor you will need to use property nodes of the Waveform Graph. A good start would be the property cursor>>cursor position>>all elements.

Bug in Digital Waveform Graph X-Axis

Hello,
I am making separate queried to a database to retrieve analog and digital data over the same time period. The data were logged at 2 second intervals. I have verified that both result sets return the same number of values with the same t0 and dt. I then plot the analog values on an XY Graph and the digital values on a Digital Waveform Graph. I then use property nodes to sync the two graphs (left and right plot bounds, XScale.Range, and Cursor Position.X). After doing this, I can see that the datasets do not line up between the two graphs. The data on the Digital Waveform graph ends several seconds sooner than the analog data. The x scales of the graphs appear to match but the plots don't align in time.
Has anyone else observed this behavior? Is there any work-around?
Thank you,
Peter

There is a much simpler way to synchronize these charts. Just use a stacked chart.
If you use a bundle function you can take two signals (almost data type) and wire them into a Waveform Chart together.
Then on the front panel right click on the chart and select Stack Plots
Since you only have 1 X axis now they are instrincly synched and will always write valules at the same time and update the UI together. You can skip all of the scale synching....
Since the data you are working with has lincked time stamps, the data will need to be matched, (make sure the samples are anyched and each itteration both would have the same number of samples.
The last allternative would be to strip the time stamp off of your data then build a new data structure, with the digital data, analog data and 1 set of matched time stamps. You can then plot this on an XY chart using the time stamp for the X axis for both of your other plots. Let me know if you have other questions.

Change the x axis scale markers in a waveform graph

Hello all,
I am looking at an unusual graphing problem that hopefully has been solved. The problem is because an pre-existing DAQ graph does things in a chart-like manner.
The application context is that I measure a signal vs. test length. During the test, I calculate the UUT position as a function of the test length. The test includes measurements out and back. Rather than graph signal vs. length; I want to graph signal vs. position. I have considered the XY graph, but that co-locates the position data. To remain consistent with an existing test program, I want to change the X Axis marker labels from distance to position at each marker's distance.
I would like to customize marker text for a waveform graph's X Axis. I found a sub-property node for marker text, but it does not seem to iterate through a Waveform graph's X Axis markers.
For example, a test measures the distance 0 to 200 and the X Axis markers are labeled {0, 50, 100, 150, 200}. How do I change those labels to {0, 50, 100, 50, 0}?
The Marker Values[] property node does not do what I expected.
Thanks,
Kenneth
Possible solutions:
1. Find a property node that does the job
2. Use custom indicators for each marker's labels
3. Use two graphs, one for forward, the other for reverse testing
4. XControls

For your option #4 I would use option #2 but use a single picture and hide the X-Axis and do my own.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Looking up the values in a waveform graph with a mouse click

Hi,
Does anyone know how to look up the values in a waveform graph with a mouse
click but... without the cursor legend on, if i press in the waveform graph
nothing happens, i must search my cursors and only then i can see the values
of my signal data?! Isn't there any other way?
Best regards,
Thijs Boerée

Dear Chad,
I know of the function "bring cursor to center". I also figured out that
when i use a property node of the cursor array of clusters, that i can see
that some values change when i move the cursor (i can see the X and Y scale
value change of the graph and also the values of the mouse pointer (in
points due to screen resolution)) But in this cluster i can't set the mouse
position. I allready made a VI where i can see the bounds of my
waveformgraph and I have the Xscale (min and max) and the Yscale (min and
max), with a linear fit i can translate my mouse position to X an Y scale
values and when i click on my waveform graph the cursor go's to that
position (property node of the cursor position), only disadvantage is that i
only have the bounds of my plot area and not the position, i do have the
position of my waveform graph but the plot area isn't allways in the center,
if i could extract the position of the plot area i may find a solution to
solve this problem.
And to file a product question:
I would like to see the function that with a mouse click a little menu
appears and that there are options to for example set a marker on that data
and when you right click on it, that there are options to remove it or to
add comment, a 2D array could make a list of the different channels with
it's markers (time stamps and comments).
Best regards,
And thank you for your help.
Thijs Boer�e
"Chad AE" schreef in bericht
news:[email protected]...
> Dear Thijs,
>
> Thank you for contacting National Instruments.
>
> To address your question, there is no direct VI, command, or property
> node that will allow the cursor snap-to-mouse functionality.
>
> I notice a problem you may be occuring is trying to find where the
> cursor is on the graph. If this is an issue, you can select Bring to
> Center from the Formatting Ring on the Cursor Legend to move the
> cursor to the center of the graph.
>
> Let me know if you have any further questions or if this does not
> resolve your issue, as I would be happy to file a product suggestion
> so that LabVIEW is improved in future versions.
>
> Thanks again and have a great day!
>
> Chad AE
> Applications Engineer - National Instruments

Working with dynamic scales in waveform graph - display problem

Hello
I want to use the same waveform graph in the frontpanel for different measurements. These measurements contains 1 to 8 curves, some of them I need to autoscale and others I want to use fixed scales. I wrote a method containing these functions and the functional behaviour is how I expected. But when it runs several times, LabView cannot correctly manage the graph display. Some scales are behind the graph or two scales are at the same position.
Perhaps you have a look at my example VI (LV 7.1), I generate a random Waveform and want to display a random number of curves and some of them in fixed, and some in autorange. The more I run the VI, the more the waveform graph display gets wrong. Does anybody know a solution?
Thank you very much for answering!
sparti.
Attachments:
ScaleProblem.vi ‏165 KB

hi there
Ben, thanks for the link. Christian's suggestion is right and describes a similar problem.
I solved the problem now on an other way. Each time before I change the visability of the scales I reset all settings to the default (startup) values by property nodes (YScale.Maximum, YScale.Minimum, All Visible...). Then I make the scales which I don't need unvisible, link the graphs to the prefered scales and set the Min/Max or autoscale.
Important: I got 4 scales on each side. When I want to use eg 2 scales on the left, I need to make visible scale number 1 and 2. Scales 3 and 4 can then be set to unvisible (in other words in an incrementing order).
Makeing scales visible and unvisible is a little bit nervous on the screen. So, during that process I bring a picture of the last waveform on the top of my screen and change to the graph view when all settings are done.
Now I got a really great waveform viewer with the possibility, scaling some graphs by autoscale, others by fixed scales, using up to 8 scales selectable on the left/right side, user definied colors, names and units.
Thank you all for taking part of my problem.
sparti

Waveform graph Y positions

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