Scrollbar for a waveform chart

Hi, I make the scrollbar visible in the front panel, but it's always gray out as shown below. How can I fix this? Thanks!
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Hi kwang,
switch off x axis autoscaling…
As long as the x axis is autoscaled (and so shows all available data) there is no need for the scrollbar!
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Similar Messages

Strictly typed refnum vs normal refnum for a waveform chart

I know that one way of clearing a waveform chart is to write an empty array to the 'history' property of the charts property node. The help file for this states: "use strictly typed refnums when reading this properrty"
I am looking at a program coded in LV 8.6
a number of control refnums are carried around in an array (so strict typed)
in some cases (but not all) the programmer used "to more specific class" to designate a waveform class when writing to properties for scaling the Y-axis, etc. Other times this is not done(?)
We are now having an issue which appears to be that the chart is re-initialized when dynamically rescaled (I am not sure if that is what is going on, but that is what it looks like).
It looks like when the chart is dynamically rescaled the previously acquired data is gone and the chart starts populating fresh.
Haven't figured out what is causing this, and I am wondering if strict type refnums vs generic refnums may be a factor?
Lawrence M. David Jr.
Certified LabVIEW Architect
cell: 516.819.9711
http://www.aleconsultants.com
[email protected]

Waveform charts can hold different data types (they are polymorphic), such as DBL or 1D-array of DBL. When you want to set the history, you need a 1D DBL or 2D DBL respectivily. The correct data type is part of the 'strict type', I guess you will get the default instance if you use the non-strict (generic) type.
But if this is releated to your problem, I can't even guess.
Felix
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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

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

Customizing X scrollbar of a waveform chart

The problem of the X scrollbar of wavechart is that it's a one color scrollbar and the contrast between the background and the foreground of that scrollbar is not strong enough.
So i tried to modify it using the "customize control" option. But i can't find the way to make it bicolor.
Can somebody help me?

Benjamin
I think this was answered already here http://forums.ni.com/ni/board/message?board.id=170&message.id=186248
David

To more specific class for waveform chart

Dear All
In the attached VI diagram the "To more specific class" gives an error messag:
LabVIEW: Type mismatch: Object cannot be type casted to the specified type.
so it can not work for my waveform chart. I think I changed some properties or some thing similar for my chart that can not work with this routine because it works for new instances of waveform charts but whatever I try to find the difference between my waveform chart and a new instance of waveform chart I don't not find any difference.
Do you have any clue?
Best regards
Afshin
Attachments:
VI2.JPG ‏59 KB

Try to use the "Controls[]" and the "ClassName" property instead. See attachment.
Best regards
chris
CL(A)Dly bending G-Force with LabVIEW
famous last words: "oh my god, it is full of stars!"
Attachments:
WaveformChart.JPG ‏61 KB
WaveformChart_85.vi ‏18 KB
WaveformChart_85_CTL.ctl ‏9 KB

Average value for waveform chart

Hello everyone.
Can i make a time interval, where i can measure average value for a waveform chart ?
for example fom 0:30 to 0:45
I have uploadet my VI
Thanks in advance
Oesen
Best regards
Oesen
Solved!
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Attachments:
Trykmaaling.vi ‏83 KB

Oesen,
When you are displaying data on a chart, the newest data is appears at the right of the previous data. When the chart history buffer is full (default length = 1024), adding a new point deletes the oldest point. Visually it appears that the data slides to the left as new data is added to the right end.
My question relates to how the user would "tell" the program what data to average. In the image you posted you marked a segment of the data to be averaged. Suppose the user marks point "A" as the beginning of the segment. While the user is deciding where to put mark "B" additional data is acquired and point "A" disappears because it is beyond the history length. What does the program do in such a case? A slight variation is the situation where both "A" and "B" have been marked but some of the data is deleted from the history before the averaging or other processing has begun.
Lynn

How do you set the size / bounds of a waveform chart at run time?

I have a plot area that I would like to fill with as many waveform charts as the user specifies (at run time). The "bounds" property is read only and I haven't noticed an additional "size" property for a waveform chart as there is for a button. Is there a way to set the size of a waveform chart at run time, and if not, why not? (Labview 6.1)

Look at it a little more carefully, I suspect that your assumption is only half wrong. The property does only resize the plot area--LV resizes the frame to fit the resized plot on it's own.
You'll need to bear this in mind when you're figuring-out what size to set the property to.
Mike...
Certified Professional Instructor
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LabVIEW Champion
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How to set waveform chart to start data since beginning of run

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Attachments:
TCs.vi ‏106 KB

You need to check the update mode of your chart.
Strip Chart—Shows running data continuously scrolling from left to right across the chart with old data on the left and new data on the right. A strip chart is similar to a paper tape strip chart recorder. Strip Chart is the default update mode.
Scope Chart—Shows one item of data, such as a pulse or wave, scrolling partway across the chart from left to right. For each new value, the chart plots the value to the right of the last value. When the plot reaches the right border of the plotting area, LabVIEW erases the plot and begins plotting again from the left border. The retracing display of a scope chart is similar to an oscilloscope.
Sweep Chart—Works similarly to a scope chart except it shows the old data on the right and the new data on the left separated by a vertical line. LabVIEW does not erase the plot in a sweep chart when the plot reaches the right border of the plotting area. A sweep chart is similar to an EKG display.
From the help menu:
The waveform chart maintains a history of data, or buffer, from previous updates. Right-click the chart and select Chart History Length from the shortcut menu to configure the buffer. The default chart history length for a waveform chart is 1,024 data points. The frequency at which you send data to the chart determines how often the chart redraws.
Attachments:
resp2.jpg ‏36 KB

How do you reset Waveform chart to blank?

I have a VI with a Waveform chart in the WHILE loop, and each time I STOP the vi and re-start it, the old data remains in the display and moves out only as new data is collected. This old data persists even after the VI is closed and re-opened.
Is there a way to remove the old data each time the VI is run, in other words to make the blank screen the default for the Waveform chart? Right now, every time I open and run the VI, there is a squiggly line in the display, from irrelevant/useless data collected previously, and it would be cleaner and less confusing if there was no old data displayed there.
Thanks,
Dave
Solved!
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Thanks, but, still confused. I already have a data source wired to the Waveform graph. I cannot wire two things to the Waveform graph...so...can you offer more information? See the vi below....Waveform graph allows only one thing to be wired into it....
Are you suggesting wiring an empty array each time I use the VI and then reconnecting the data source?
Attachments:
waveform graph question.jpg ‏19 KB

Export all data from my waveform chart to excel

Hello, my name is Chris. I am just learning to use LabView. Everything I have learned so far is through these boards. Which is a valuable tool for someone learning. The VI I am working on is to monitor current from a unit we are testing. I am able to monitor current and have it running in what I believe to be real time. As I said, this is the first one I have made. I am trying to export all the data from my Waveform Chart to a report. Everytime I try I get one instance and it measures 0. I don't know what I am doing wrong. Any help would be appreciated. Also, if you have any suggestions on the all around working of this I would appreciate that as well. Thank you in advance.
Attachments:
Lp Current Test.vi ‏83 KB

Hey Christophrt,
If you are trying to display the microseconds for a waveform chart in LabVIEW here is how you can do it:
Go to the Chart Properties>Display Format>X-Axis>Advanced editing mode>enter:
%<%I:%M:%S%6u>T as the format string and you will have the hours: minutes: and seconds to the microseconds.
If you are trying to display the exported data in microseconds in Excel, you will probably have to do some formatting changes in Excel to have that work.
Regards,
Tommy G.
Applications Engineer
National Instruments

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

Horizontal scrollbar of waveform chart in tab page resets to end when tab page switched

I've got a VI in LV 2012 with a chart in one of two pages of a tab control. Whether compiled to an executable or not, when the waveform chart contains data that is no longer being updated and the x-axis range doesn't show the last point of data, the horizontal scroll bar auto-adjusts to show that last point if you switch pages (back to the chart) on the tab control. I've tried turning off Autoscaling but that doesn't stop the effect.
Additional issues:
On some of these attempts at reproducing this, the X-Axis will even change scaling, zooming in on the data.
When data is pushed left by this bug to allow displaying the furthest data point, if the leftmost area of the chart was blank before the data was pushed left, the data pushed left into the formerly blank area will not be displayed. This happened only when the X-Axis was manually autoscaled prior to pushing the data off the right edge of the chart, and only if the x-axis scale was not changed. If the tab pages are again switched at this point away and back to the chart, the data re-appears.
The chart is a stacked plot if that makes a difference, Also, the tab control is not linked to any event handlers.
Also, the scrollbar works fine if you scroll such that the rightmost data points are on the chart along with blank area to the right, whether there is more data off the left edge of the chart or not.
Last, the Y-Axis of each stacked plot is unaffected by any of this.
I hope this isn't a duplicate - I didn't find it in the forums.
Thanks,
Erik
Attachments:
Flaw Demo.vi ‏120 KB

Alex,
Thanks for the quick response on this. Again, the charts are awesome except for these minor fiddling details. Sorry about the terminology confusion - I didn't find anything in the Help system naming the legend buttons, and unfortunately I can't edit the prior post. When I said "AutoScale LocK" I meant "Scale Lock", and "AutoScale Once" I meant "Autoscale".
Here are the issues, hopefully clarified:
1. If any chart elements have Scale Lock set, pressing the AutoScale button for any plot causes these other plots to autoscale as well. Note these are not plots with multiple Y scales, they're stacked plots with separate y-scales for each plot. Changing the "Advanced->Auto Adjust Scales" parameter had no effect on this issue.
2. If none of the chart elements have Scale Lock set in the scale legend, pressing the Autoscale button for the X-Axis has no effect if the x-axis was previously set to show all the data history but then panned such that some data falls of either side of the chart.
This may have been confusing, so here's a breakdown of the steps to re-produce the problem using the VI I previously attached.
a. AutoScale all elements of the chart, and turn off Scale Lock on all elements
b. Move the data to the right in the chart, so the left half of the chart area has no data (e.g., set the X-Axis range to -5 to 6 seconds)
c. Press the X-Axis AutoScale button. The X-Axis range will not change from where it was in (b).
3. The Y-Axis will also auto-scale when returning to the Chart tab if Scale Lock is enabled for the plot with the fix for the x-axis scale in place (restoring the Xscale.Range parameters from a local variable). If the fix is not performed, this doesn't happen.
4. Pressing the Scale Lock button on one of the plots causes the X-Axis scale to be lost IF there is data past the maximum displayed X-Axis range. It looks like it set the X-Axis to the same problem range as before the fix was in place. I don't know how to build an event case for this, except for possibly "Mousedown?".
One more:
5. Enabling Scale Lock on any plot auto-scales any other plot that has Scale Lock enabled (assuming the user changed the Y-Axis range from the previously auto-scalled range). Obviously this is linked to #1 above, but worth noting.
Thanks again, Alex!
Erik

Any alternate solution to using Waveform Chart Property Nodes 'ActPlot', 'Plot.Visible' for mulit-plot color problem on PDA?

Hello,
    On a waveform chart, 4 signals need to be plotted based on the status of 4 boolean inputs. Eg. if the first boolean input is true, the first signal needs
to be visible on the waveform chart; if the first boolean input is false, the first signal should not be visible on the waveform chart and so on. This can be
done on LabVIEW desktop using the Waveform Chart Property Nodes 'ActPlot', 'Plot.Visible' - a sample VI "BundleSignals_Select_Desktop.vi" is attached for
reference.
    But on PDA, since the Waveform Chart Property Nodes 'ActPlot', 'Plot.Visible' are not supported, some other method has to be used. I have done the
selection/de-selection of these signals using 'Insert', 'Delete' array functions as shown in the attached VIs "BundleSignals_PDA.zip" which works, but the
problem is that the colour of these signals do not work as desired when the selection/de-selection of these signals is done - It is required that the first
signal should always appear in White color, the second signal should always appear in Red color, the third always in Green color & the fourth always in Blue
color.
    I hope i have made myself clear of the problem. Has anyone faced this problem before & is there a solution?
Note: Version of LabVIEW that we are using: LabVIEW 8.5 Professional Development System for Windows Vista/XP/2000 and LabVIEW 8.5 PDA Module for Windows
Mobile.
Thanks & Regards,
Subhashini
Attachments:
BundleSignals_Select_Desktop1.vi ‏25 KB
BundleSignals_PDA.zip ‏26 KB

Unfortunately the only alternative to using property nodes is to set the properties manually on the development environement. The limited size of memory does limit us in terms of features for the module.
Mehak D.

How to update the absolute time value in waveform chart for labview 6i?

Hey there,
I'm developing a control system using labview 6i on win 2000 os.I'm receiving the sensor data every minute and i want to display the data on a waveform chart with absolute time scale on x-axes. I'm using the property nodes for the offset, multiplier and maximum values putting them outside the while loop and giving them input using get date/time in seconds function. the problem is that the time doesn't gets updated w/ refernce to the computer time and after a certain period the time shown on x-axes lags by several hours. any advise?

Posting an example ussually help us nail these types of issues fast.
I am therfore forced to guess.
Do you have your code written such that the scale operations occur before the loop?
The next thing I have to suspect (not being able to see your code) is if your dt is correct. If your dt is larger than what the chart is set for, then the time will fall behind.
I have included an image showing how the chart can be used to show multiple sample rate plots such that the t0 of the readings are used to control how the readings are displayed. This example uses waveform data types (I believe they were available back in 6i). It should serve as a guide to do what you want.
I suggest you start by recreating the demo and play with it until you have what
you will need in your app.
The beauty of this method is it lets you use the chart to plot signals acquired at different frequecies and plot them all together.
reply to this answer if you have questions,
Ben
Ben Rayner
Certified LabVIEW Developer
www.DSAutomation.com
Ben Rayner
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Attachments:
Wform_demo.bmp ‏427 KB

Scrollbar for a waveform chart

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