Waveform graph - Number of major ticks on x scale

Hello all!
I'm trying to display meteorological measurements throughout a day in a minute resolution. For that purpose I'm using a Waveform Chart with fixed length on x-axis (0-1440). However, major ticks are distributed by 100, i.e. 0, 100, 200, 300, ..., 1400, 1440. How can I distribute these points by 60, so that I can put hour labels 00:00, 01:00, 02:00 etc.
Thanks!
Regards,
Marko.

There is a Marker Spacing property to which you can write a custom array. This sets the scale Marker spacing to arbitrary. See attached vi as an example. Work still needed to make it look acceptable regarding labels.
You could make the marker every 1 hour, the minor tick (not labled) cannot be controlled, A long chart will have 10 minute minor tick
- half the size of the chart and it will be 20 minute
If you want continuous output I think you need to use a Waveforn Chart rather than a Waveform Graph with chart history length set to 86400 (number of seconds in 24 hours

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Waveform graph number of points

Hi,
In my app I´m receiving data (a 10Hz sine wave) continuously (serial port) and plotting it on a chart and on a graph. After several number of points plotted, about 18000, the sine wave appears wrong on both waveform chart and graph. Is it a problem with memory?
Thanks,
Celia
Attachments:
plot.doc ‏195 KB

Hi Celia,
the vi seems to be ok.
But as I told you before:
You collect your data in the "array" by using "build array" function - this is ok so far. The you feed those data to the "array" indicator - and also to the "waveform chart". And probably here is the problem: You feed the chart with an array when you should only feed the single values! The chart has it's own memory called "chart history" (you set it to 250 values)!
The more values you collect the bigger memory blocks LabView has to allocate/calculate/move in RAM! And you keep on moving memory blocks from shift register to "array" indicator, chart AND graph. All three indicators have their own memory copy of the data, and in each iteration LabView has to allocate bigger memory blocks for each indicator. This takes it's time...
And due to this behaviour the iteration time is getting longer resulting in "undersampling" of your sin wave...
When you need constant iteration time, you should separate DAQ and display into different loops connected by queues. There are plenty example coming with LabView and also here in the forum!
I added your vi, slightly edited. Read the comments in the last frame! (You don't need a sequence here, it's all in the dataflow )
Message Edited by GerdW on 09-18-2007 09:42 AM
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome
Attachments:
RecWaveChart2.vi ‏95 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
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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 can i dynamically varie the location and number of major grids in XY graph.

Hi All,
I'm supposed to plot some statistics in X-Y graph with x-axis scaled on time stamps. The plot generated has only one major grid. Can I have a control over the location and number of major grids dynamically?
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Hi Saravanan,
use a property node "X scale.Range.Increment" to set the spacing of the major grid...
Best regards,
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CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

How do I determine the number of plots on a waveform graph?

How do I determine the number of plots that have previously been plotted on a waveform graph? I am loading dynamic data from a file. If I convert to an array and size it and there is only one plot, I get the number of data points and I don't know how to tell the difference.

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a division of Test & Measurement Solutions

Programmatically Changing Waveform Graph and the number of plots

I have a waveform graph that needs to display a variable number of plots based on the number of inputs. Is there a way to programmatically adjust the number of plots displayed on the waveform graph?

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Attachments:
plot names.JPG ‏37 KB

Waveform-Graph - Specify number of divisions (lines)

Hello,
is there a way to set the number of vertical and horicontal lines in a waveform-graph?
I want to change the look that it looks like an osciloscope-display with 10x8 divisions.
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Thx

Hi OnlyOne,
so you don't want to use gridlines? You want some kind of overlay?
Options:
1) Put a picture indicator on top of your graph. Make it transparent background. Draw lines as needed - and you can choose any color...
2) In LV8+ you can put a picture in the background of a graph. So create a picture like in point 1 and set it as background in your graph (using property node).
3) Create property nodes for your decorations and change the color of those lines: Open reference to vi, get panel -> decorations[] -> colors... Or use the coloring tool ("brush") at edit time!
Why not use gridlines of the graph?
Message Edited by GerdW on 05-14-2008 01:28 PM
Best regards,
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Kudos are welcome

Business Graphic UI Element - Major Ticks Property

Dear All,
We have a requirement to modify the existing Business Graphic UI element (Line Graph).
We are not able to increase the major ticks property of Business Graphic UI element to 21.
Are there any constraints on this property ?
Thanks.

Hi,
Do you mean the properties of the ValueAxis-Line, Number = 21 and Major tick calculation = Manual ticks?
I do not see a restriction. Everything works fine.
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Regards, Kai

How to connect with waveform graph?

hi
i would like to know how to simulate wave form graph the input is randon number ?My problem is i cannot connect with wave form graph...
can u show me example..like using arrary...or something else..i looking forward ur reply
thank u

I have an example that you may want to look at here.
The example was for a signal generator, but there is a waveform graph to show the selected waveform. It is an extremely basic program, but might be a good start.
RayR

Y scale flip in waveform graph when using property node.

I'm having problem with property node. I'm trying to build a stackable scope with Waveform Graph And dynamically change the number of plots. It is working. But The Y scale is flipping. The minimum goes on the upper part and the minimum scale goes down. when I change it appearance it's not very fast. It take about 1 or 2 second on my computer.
The way it is build actually is:
Cluster_1 is containing 8 clusters. And each of the 8 clusters are containing a Waveform Graph. By reference I change the property of each Waveform to make visible or not each of the Waveforms.
First I would like to solve the scale problem and second accelerate the redrawing of my scope.
Maybe there is an other way t
o do what I need.
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Nitrof
Attachments:
MultiScopeExample.llb ‏192 KB

Wow, you have a neat program! The problem with your y axis flipping is because the last four charts in the cluster were programmed with a flipped axis. I relabeled the charts and it worked correctly.
From what I could tell with your code, you do not need the sequence structures. The one inside of the even actually runs the same code twice. Remove this duplication and you should see improvement. Also clusters are slow, so you should not expect it to blink back with additional coding. Use defer panel updates to get that behavior. I incorporated these changes and attached the program.
Jeremy Braden
National Instruments
Attachments:
MultiScopeExample.vi ‏163 KB

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.

How do I get the reference numbers for cursors in a waveform graph (other than through an event structure)?

I want to control cursors in a waveform graph programmatically. I've tried using the "Cursor list" property, modifying the cursor clusters and writing the results back to the cursor list property, but this only works sporadically. Modifying the cursors by ref number works well, but you have to get the refnumbers from an event structure during a cursor event. Is there any way to get cursor reference numbers aside from through an event structure?
Thanks!

Hi barryinbo,
On the controls pallette, go to refnums> Control refnum>Control. Then right click the refnum and point to select vi server class>Generic > and you will see a cursor there. This will be a "loose typed refnum" but you can right click the refnum to include data type. An alternative is to drag a cursor to the refnum, this will make it strict typed.
Hope this helps
Chris Co.

Real time waveform graph in while loop

Hi
I have a VI which includes a subVI that reads data from an oscilloscope and presents the output in the form of a cluster made up of the initial time t(0), a time interval delta t and an array of voltage readings.
This cluster can then be wired to a waveform graph in the usual way. All of this is situated within a while loop in my VI and on each iteration of the loop I obtain a waveform graph of the voltage readings starting at the same time t(0) and ending at the same time t. However I want my graph to begin at a time t(0) when I set my VI running and then continuously acquire and build up the data on each iteration of the while loop so after my VI has finished executing I have a complete graph of all the voltage readings acquired after the set number of iterations of the loop. I know on the Express X-Y Graph VI you can double-click the node and deselect the box that says 'clear data on each call' - if I could do this in my case that would be great but I can't use an x-y graph because I have an array of y-values to plot on each iteration.
If anyone can help me out it would be much appreciated - I'm sure there must be an easy solution to this but I'm going out of my mind trying to find out what it is!
Many thanks,
Bex.

As usual, you have several options.
You can use an XY Graph by generating the X values yourself. This will ensure that you place the data exactly where you want it on the X axis. This is fast, but does involve a memory cost.
You can use a Waveform Graph with a waveform input instead of the cluster you are using. Use the Build Waveform primitive instead of the bundler to make your waveform. Set the t0 values to the appropriate values (negatives do work, as do small numbers - time is in seconds, use the To Time Stamp primitive to convert from DBL to timestamp). Finally, you need to set the Waveform Graph to use the t0 values. Pop up on the Waveform Graph and make sure Ignore Time Stamp is not checked. Depending on your version of LabVIEW, you may have to pop up on the graph or the axis. When you unselect Ignore Time Stamp, you will probably want to reformat the X-axis again. The Waveform Graph clears data at each iteration, so you will need to replot all your data each time. Just create an array of waveforms and keep adding to it. The t0s will put the waveforms in the right places. Yes, this may cause memory problems.
Finally, you can use the Waveform Chart, which does have memory. Create the waveforms like you did for the Waveform Graph and send them to the chart. It will remember what was sent to it from run to run. Make sure you set the Chart History Length (pop up on chart and select Chart History Length...) to long enough to hold your entire data. You can use a property node to get the data back at the end, if you need to.
Good luck!
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Waveform graph

I am wanted to display mutliple waveforms in a waveform graph, I have the following challenges to figure it out.
Someone please guide me to do this
1) Input is only 1-D array(which gets updated in run time), but waveform graph is accepting only 2-D array as input to display multiple signals.
2) Iam using the attached waveform, which works as a waveform chart and wanted to feed the 1-D array to this vi.
(Found this vi in a post). I want to go with only waveform graph because of the cursor option availabe in the Graphs.
-Zhang
Attachments:
Waveformgraph.vi ‏14 KB

Thank you very much srikrishna for your reply, I was looking some thing similar to this logic.But the only other thing I wanted to add to this logic is making the x-axis to run with the time (X-axis always stays at the same scale),allowing the user to look at the data right from beginning using the graph palette, when he stops the execution .
I had inserted the array, replacing the random number generator and was able to verify the data, which is updating correctly during run time. Iam attaching the modified vi. Can you please tell me how to change the x-axis so that it runs with the run.
-Zhang
Attachments:
Graph_data.vi ‏11 KB

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 - Number of major ticks on x scale

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