Graph cursor property

My waveform graph has two graphs overlaying each other. The graph has two mult-plot cursors. Each cursor is watching a different plot. I tried to use the property node to move the cursor, and it seems like the cursors will go there for a split second and go back. Why is that? How do fix that?
Also, on the cursor lengend, all I care about is the x values from each cursor. Is there a way to format the legend as following?
cursor 0x1
cursor 1x2
See attached VI.
Kudos and Accepted as Solution are welcome!
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Attachments:
cursor.vi ‏27 KB

You need to use "Map XY to coordinates" to transform the coordinates. Here is a quick rewrite. See if it suits your needs.
LabVIEW Champion . Do more with less code and in less time .
Attachments:
follow a ball_MOD.vi ‏34 KB

Similar Messages

Mixed Signal Graph: Cursor Position Property for Multi-Plot Cursor

I'm working 6 waveforms on 3 different plot areas in a mixed signal graph in LV2009. When I try to pull the Cursor.PosY property from my cursor (in which Watch All Plots is True, and is set to Multi-Plot in the graph properties), it returns the value of only the first plot in the cluster of waveforms fed into the graph. I've tried changing the active plot, active plot area, nothing changes. I am able to retrieve each value via the cursor legend, but I cannot pull each of those values into another portion of my program. Also, I noticed that when setting events in an event structure, any events relating to a cursor drag aren't present as they are in a waveform graph. My workaround is to create an indicator for the Cursor.PosX property and monitor when that value changes, but I feel there should be an easier way. Any help is appreciated.
Thank you in advance!

Jeanius,
I am not quite sure why the cursor pos in the Wavegraph reference does not change when you change the active plot, but if you grab a reference to the specific cursor and then change the active plot things you receive the expected behavior.
Ben J.
National Instruments
Applications Engineer
Attachments:
MODDEDmixed graph cursor ex.vi ‏41 KB

Moving xy graph cursor with mouse and programmably controlling snap to point

Hi,
I have run into a bit of a problem. I am trying to create a program which allows a user to select a location on an XY graph by simply clicking in the vacinity of the plot. Most of it is working, however I find that I can't programmably control the snap to point function reliably.
I hope this is a clear outline of the problem:
- The cursor starts in a Free state, so that when the
user clicks in the plot area, I can set the cursor
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CursorPosition using the graph's property node.
- Maybe the user didn't like the chosen location and
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the cursor to a new position.
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e cursor position is probably not exactly on
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to Snap To Point, the cursor does not snap to the
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How do I go about getting the cursor to snap to the closest point at it's new location? I'm at a loss.
Any insight you might have would be greatly appreciated.
Thanks much!
Tere

So what is the question about... I have to use XY graph in my program. It is used in Loop while cycle. It shows the statistic of a variable. I am using cursors in this graph to check the actual value of a variable in different period of time. But there are 7 variables and it is extremely hard for user to check each value independently. So I tried to make them moving on the X axis (TIME) together using the property node (cursors reading the position (only X axis, Y axis status lock to plot) of the major cursor and follow it... Everything looks great? But it did not work when I am trying to move the major cursor manually on graph... It works only when I am using the cursor movement buttons... But they work very slowly when there is a lot of data in graph.
I want to find out is it possible to make seven coursers mouthing together By the X axe and be Locked each at its plot by Y axe manually (Using mouse moving on a graph). Is it possible? If it is than how to do it?

XY Graph cursor Error

Hello
This error was found, when I started using LabView 8, with my old LabView 6.1 VI's.
I have encountered a minor error on my Graph display. I noticed my Y-Scale numbers go negative, if I Press and Hold my Graph cursor, while I am moving it.
I run this same test using New LV 8 XY Graph and numbers do not go negative, but they surely flicker a lot + numbers still change some.
Have you noticed this before? Is there some new property I need to set up, to make my LabView 6.1 Graph stable? Is this known bug or am I just doing something wrong?
Here is VI for your testing. My LabView 8 version is 8.0.0.4005.
Just run it and while moving yellow cursor (press+hold+move), after 1-2 seconds of holding something happens.
Yours
Kari
Attachments:
Cursor Test.vi ‏84 KB

Hello Karik.
I experience the exact same problem in the application I'm programming.
The only solution I have come up with is having the cursors Y-axis
centered in the visible area of the graph.
However this is really bad because there is will create a smal "hole"
in the cursor bar, it looks awfull. I think this is a bug in lv8 since
in lv7.1 I could tie down the y-axis to like -10000 or something and
the problem would not appear.
Hope NI fixes this problem really really soon.
//Andreas

XY Graph Cursor Problem in Labview 7.1.1?

Hallo,
I am using Labview 7.1.1 and I am facing one problem with XY graph cursor. If I am moving cursor in one graph, I am expecting same movement in another Graph. But when I move cursor in Graph1, cursor in second graph moves but not to exact X value of Graph1.
Property of Cursor in both graphs must be "Lock to Plot"
If any body knows about this please let me know ASAP. I am attaching example VI for your reference.
Thanks,
Sashi
Attachments:
XY Graph Cursor Problem.vi ‏101 KB

It's a curious effect. Probably the floating point coordinate is sensitive to the exact pixel alignment (I mean that this would not happen if we had for example 1 pixel per point in the X direction).
Anyway, if you use Cursor Index instead (which is an integer) the behaviour is as expected.
Paolo
Paolo
LV 7.0, 7.1, 8.0.1, 2011

How to set cursor property from "snap-to-plot" to free?

dear all,
is there any one know how to set a cursor property from "snap-to-plot" to "free"?
this cursor is in a XY graphy
i couldn't find coresponding property in the XY graph property node
thank you
Jack

It looks like there are different property names depending on your labview version.
You need to select the ActCrsr and then use the Cursor.Lockstyle property in LV7.1
You need to select the ActCrsr and then use the Cursor.CursorMode property in LV8.2.

Qucik Graph Cursor Legend Questions

Hi all,
I have a couple of quick questions regarding my graph cursor legend:
1. Is it possible to move the position of the cursor legend during runtime? I cannot seem to drag it around the graph?
2. Can I hide/remove the cursor mover? This is not needed and is for this vi as I need to be able to manually drag the cursors only.
I am accessing the cursor legend during runtime through a right-click and selecting "visable items:.
Thanks,
Jack

Hi please check Using Cursor Legend in this link if it is helpful
http://zone.ni.com/reference/en-XX/help/371361J-01/lvconcepts/customizing_graphs_and_charts/
Sorry i don't know exact answer for questions, But did you try property node of Cursor.
-To access it, right click the graph indicator in Black Diagram and go to create>>Property Node>>Cursor.
-Lot of options regarding cursor available there, you can make selected property to write or change the parameter. and check this for help on cursor properties
http://zone.ni.com/reference/en-XX/help/371361J-01/lvprop/cursor_p/
Thanks
uday,
Please Mark the solution as accepted if your problem is solved and help author by clicking on kudoes
Certified LabVIEW Associate Developer (CLAD) Using LV13

Why does the graph cursor (snap mode) snap to unvisible curves? How can i change that?

I display several curves in one graph. To get a better overview the user can filter unwanted curves by setting the attibute to unvisible. There is one cursor switched on in the graph with the option "snap to plot". The user can move the cursor and read the coordinates and curvename. Unfortunately the cursor snaps also to the unvisible curves. How can I block that behaviour? The cursor should only jump on the visible curves.

> with the property Cursor.Plot I can set or get the current plot number
> of the cursor, but I cannot prevent the user to move the cursor to an
> unvisible plot. Labview allows the cursor to be moved to a curve witch
> is unvisible in the graph. I want the user only to be allowed to jump
> betwen the visible curves.
>
The graph cursors can be locked to a particular plot or set to snap to
any plot/point on the screen. You cannot see invisible plots, and you
probably can't see black plots on a black background, but the graph
intentionally lets you place cursors there and other users wouldn't be
happy if it changed.
What we will likely add at some point is a way to truly show and hide a
plot. In the meantime, you can also just change w
hat is plotted.
Hidden plots can be removed, no points, and the cursors will not go there.
Greg McKaskle

Calculate from graph cursor data

I need to calculate from cursor data in a grpah that has been read from a file and displayed. Specifically, I want to position locked-on-trace cursors and calculate the delta-time or delta-voltage from their positions like one would with a standard scope. Attached is a file of the trace to read, 2 channels, Cursors would be on either ch-1 or 2. Simple read VI attached.
Attachments:
Read_and_chart_data.vi ‏31 KB
s250.txt ‏13 KB

Here's a very simple example. You just have to use the graph's property node to get the cursor position. If you know the sample rate, you can fine tune it to display actual time.
Attachments:
Read_and_chart_data_mod.vi ‏44 KB

Bode magnitude graph cursor not following plot

Hi,
I was wondering if anyone would be able to shed some light on a problem that I am having regarding an XY graph cursor.
I have developed a simple VI to determine the characteristics of a low pass filter using a sine wave ramped in frequency and subsequently monitoring the gain of the filter to create a Bode plot.
Through analysis of the Bode plot I would like to determine the cut-off frequency of the low pass filter under test. I have introduced a cursor into the graph and using a property node I hoped to drive the cursor to the -3dB point in the Y axis and output the cursors corresponding X position thereby determining the cut-off frequency of the filter.
However the cursor never seems to follow the plot beyond the first step of the loop. It feels as if there is a break in the plot between the 1st and 2nd iteration of the while loop used to ramp the signal generator.
I've tried to work out why the cursor won't follow the plot to -3dB but so far I am stumped.
Any help or advice that you could provide would be greatly appreciated ! I have provided the attached VI for clarity.
So liberate your minds and give your soul expression. Open up your hearts, I'll sing for you this song. Let the people sing !
Solved!
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Attachments:
LPF Auto Test.vi ‏109 KB

I have corrected your VI.
First, you needed to put the property node AFTER the while loop, because you need the graph to be done first and then look at the frequency cut off.
Second, in LV, the property nodes are read from top to bottom. So you need to place the cursor at Y = -3 first, and then read the X position.
I attached the corrected vi
Giuliano Franchetto
Student at the l'Ecole Nationale Supérieure des Mines de Saint-Etienne, cycle ISMIN (FRANCE)
Attachments:
LPF Auto Test.vi ‏109 KB

Programmatically fire graph cursor move event

Is it possible to programmatically fire the Graph Cursor Move Event ? Assigning a value to the Cursor Index or Cursor Position property node does not seem to do it.
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The graph cursor move event contains processing code for data on the graph along with front panel display of those results. Data is put onto the graph during data acquisition which occurs in another event. When that data acquisition event finishes I need to cause the processing code to execute once to update the front panel display so its results are shown for the new acquired data.
I could put the processing code into a different event that fires on say a button value change. Then the graph cursor move event would fire that button event change by setting its value change property. The data acquisition event could also fire that button event.

Error 1055 on Graph cursors.

I am using LabView 2010, expanding on one of the example vis for data acquisition. I want to use graph cursors to allow someone to zoom in on a particular part of a graph. To do so, I have been trying to use property nodes. When a graph has more than one cursor, the property nodes seem to access only the highest indexed cursor. So, I tried to apply a property node to a graph with just one cursor. In particular, I tried to access the x-value of the cursor. When I then run the vi, I get error 1055 "Object reference is invalid". I had hoped to construct the property nodes for one cursor, then add another cursor, and attach property nodes to it. There does not seem to be a way to use property nodes to specify which cursor I am accessing. I have tried a property node with two properties: select cursor as an input, and x-value as an output. The "select cursor" property input seem to have no effect at all.
Is there an example vi for programmatically extracting information from graph cursors?
Joe Rudmin
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Joe,
Please take a look at my screen shot as a reference for getting the x position for a cursor on a graph object. I hope this helps.
Right clicking on the graph and hover over create then property node, cursor, cursor position then cursor x. This should create a property node that gives the position of the cursor on the graph. I understand you are trying to use multiple cursors but this will get you started.
Kyle Hartley
RIO Product Support Engineer
National Instruments
Attachments:
cursor position.JPG ‏42 KB

How to force waveform graph cursors to show Y value on more than one plot?

Hello
Is it possible to show more than one Y value on waveform graph cursors?
Thanks in advance.
Pawel

Hi Dennis
That is correct, on graph woth multiple plots I want to display multiple Y values of plots at the same X value.
I know I can use property node to access cursor list etc. and this is how I have done it, but my question was rather if it is possible to force the cursor legend to display more than one Y value (as a native display). As a default it displays one value and you can choose which plot you want to stick to, but it would be a great feature to have possibility to expand cursor legend to display more than one value.
The question has nice consequences. If it was possible, you could use a property node to export image of the graph, control sizes, or even simple "copy" data from the popup menu. Otherwise we need to "artificially" glue the exter
nal controls displaying Y values if we want to export pictures, etc.
But since you did not answer that I supose it is not possible, as I thought.
thanks anyways.
kind regards
Pawel

How do I get an event-based response to a graph cursor change?

I want to respond to the user moving a cursor on a data (X-Y) graph. (LV 7.0)
What I really want is an event called "Graph.Cursor.Value Change", which would supply me with the new coordinates, but I see no such event.
If I use the MOUSE MOVE event to trigger obtaining the cursor values, it does not give me an event, until the cursor has stopped moving, the button is up, and the mouse moves off the cursor line.
Sure, I could use a TIMEOUT event, and read it every 100 mSec, but I don't like the time lag.
What I did was to set a flag TRUE on Graph.MouseDown and FALSE on Graph.MouseUp. I then choose an event timeout of 10 mSec or -1, depending on that flag.
That works, but is there a more direct way that I'm missing?
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
Culverson.com
Blog for (mostly LabVIEW) programmers: Tips And Tricks

No, unfortunately there is not.
To code around this limitation, I typically use the timeout event in a more complex way as follows:
The timeout is wired to a shift register that is initialized with "-1" (no timeout). The value from the shift register then crosses the event structure and feeds to the shift register on the right in almost all event cases.
I add two special event cases:
(1) "graph-mouse down" puts a small number (e.g. 10ms) in the right timeout shift register
(2) "graph-mouse up" puts again a -1 in the right timeout shift register
(x) All other event cases (incl. timeout) wire the current timeout straight across to the right shift register.
The timeout event contains the logic to read the graph cursors and associated actions.
This way there is normally infinite timeout. Once the mouse goes down on the graph, the timeout executes at relatively rapid succession until the mouse is raised again. At which point everything quiets down.
LabVIEW Champion . Do more with less code and in less time .

Graph Cursor Controls

On the graph cursor control (the 4 sectioned diamond that appears withthe cursor legend) I'm wondering what the top and bottom diamond do if anything. The left and right ones are simple enough (forward or back one sample) but the top and bottom ones don't seem to do anything from what I can tell. Are they just for decoration?
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Dan,
I never noticed that before but you're right, in a multi plot graph the up/down diamonds will attach the cursor to a different plot. I never noticed before because I usually change my cursor style so as to not show the horizontal line (just shows the vertical stripe for the cursor).

Graph cursor property

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