Waveform chart-drop in pressure

Hi,
From couple of days I am working on a code to read pressure drop in continuosly running waveform chart. I checked lot of examples and in the whole forum but I am unable to find anything close to what I need. I need to read two points from the waveform chart and difference between them. Please help me.
Thank you,
VG

Well, the VI you attached really doesn't help at all, it pretty much just shows you know how to find an Express VI from the palettes.
However, I've fixed my signature so it points directly to two tutorials (Sorry, didn't realize that I messed it up so bad). You really need to go through both, but work the first one first. Unit 2, Lesson 4 deals with arrays. But, please start from the beginning of the tutorial, because it all should help you.
Trust me, working through these first will make you much less dependent on the slow process of waiting on others in the forums to step you through your project and actually speed up the whole process, even though it takes precious time to go through them.
Cameron
To err is human, but to really foul it up requires a computer.
The optimist believes we are in the best of all possible worlds - the pessimist fears this is true.
Profanity is the one language all programmers know best.
An expert is someone who has made all the possible mistakes.
To learn something about LabVIEW at no extra cost, work the online LabVIEW tutorial(s):
LabVIEW Unit 1 - Getting Started
Learn to Use LabVIEW with MyDAQ

Similar Messages

Open waveform chart in other screen.

Hello to all!
I have a front panel with two indicators, the value of those two indicators goes to waveform chart.
My problem is that I need to call from run_time_menu to waveform chart and that it is opened in a screen different, appearing only waveform chart with titlebar.
I have proved with a property node_visible of waveform char, but waveform is in front panel and not in one second screen. Another problem is that if I use a subvi to have another screen, the values of waveform are not updated.
Thanks.
G.Garrigos.

There are lots of ways to achieve this.
One of the approaches is as shown in the attached VI.
Go through teh block Diagram of Main VI. Here you will see that a sine pattern is written to a chart.
Observe that I have placed a sub VI inside the "sub VI" event of the main VI.
Click on the sub VI icon. In its drop down menu,go to 'sub Vi node set up'. Here you will see that i have selected select 'show front panel when called' and 'close afterwards if originally opened'
This link will teach you how to pass values to a sub VI by using Connector Pane: http://zone.ni.com/reference/en-XX/help/371361A-01/lvhowto/selecting_a_connector_pane/
Run the main VI, and click on "show sub VI" to dispay the graph shown in mainVI on the SUB VI's graph
Any doubts, do ask
regards,
Dev
Message Edited by devchander on 03-29-2006 06:31 AM
Attachments:
main.llb ‏41 KB

The waveform chart in the tab control

Hi,
I'd like to change the plot number and the plot name of a waveform chart in a tab control.
First of all, it works fine without a tab control, but I have many charts(such as temperature, pressure, voltage...) so that I put each chart into the pages of a tab control.
Error 1077 happened when I "add" the plot number and change the plot name.
The following is a sample I made to describe this problem.
Let's begin if the number is 20, so there are 20 plots in that chart in page 2.
t
Do not turn on the switch, change C to 3, minus N to 18, and run it and it can be seen that the tab control will switch to page1.
Switch to page 2, and the plot names are updated but left some relic.
Add N to 22, change C to 2, and run it again.
Error 1077 happened! Switch to page 2, and the plot number is still 20, and the plot names are updated to 20.
Run it again, and it works fine!
It is very tricky for me.
If I switch to the page 2 first and run the program, it works fine too.
(That is, if the switch is turn on, then the program works fine.)
The LabVIEW version of mine is 2011.
I'm not sure I missed or misunderstanded something about this problem.
Does someone can give me some suggestion? Thanks a lot
Solved!
Go to Solution.

Hi, Bob_Schor,
I'm sorry my poor expression confused you.
All I want is to demonstrate that the chart in the 'hidden' page of the tab control results in the error when the user tried to add plot number and change the plot name.
To make a scenario more specific, there is two pages in a tab control, one is for setting, the other is for the plotting.
When the user change the channel configuration, the chart is going to change correspondingly.
If I'd like to change the plot number and plot names, there is possiby a problem when staying in the setting page.
I hope I do not mislead you to the wrong direction
You're right I should make the parameters more clear to facilitate reader understand my purpose easily.
Switch True means switch to the chart page before the modification of the chart, and return to the first page after the modification. Switch False means stay in the first page while the chart is modified.
C is used to make the plot name different among each execution. If the plot names of the chart in the previous execution are [101, 102, 103, 104, 105], and I'd like to decrease the plot names to three items [101, 102, 103], but in the case of the false switch, it will be [101, 102, 103, 104, 105], it is hard to tell if it is really updated. I can change C to 2, and the plot names in this execution will be [201, 202, 203, 104, 105], it could be shown it is updated indeed but left some unexpected plot names[104, 105](I call it relic...).
N is just the plot number the user can increase or decrease it.
I'm afraid of being the guy you mentioned...
Like my original post, I probably have several charts to show their results(temperature, pressure, voltage...) so that I make a tab control of 6 pages, and put a chart in each page. The user can also determine the channel numbers of each kind of measurement before the acquisition. I didn't think too much about it(actually now I still have this direct simple idea only...), what would you do if you have to show these data? Very thanks to your reply

Update FFT based on range of waveform chart

I am working with seismic data that I recorded from explosive events. The signatures that I'm recording could include the ignition of the explosion, the pressure wave hitting a barrier or debris hitting the ground. The objective is to analyze the waveform and see if I can see any consistancy or trends. I am loading in the seismic data into a LabVIEW program and displaying the waveform on a chart and then on an FFT. I'm noticing with most of my data there are two or three distinct frequencies, so I would like to see where these occur on the waveform chart (each event has 2-13 seconds worth of data). On the waveform chart I can zoom in on the x-axis and change the time range to look at areas of interest and count cycles, however that gets tedius. Is there a way to update the FFT to show only the data that is in the time range on the waveform chart?
Thanks
Michael

I don't have enough experience when working with the frequency domain but here is my attempt by following my nose.
There seems to be an error in the frequency detected but I don't know why. Hopefully somebody else with more knowledge will step in with an explaination.
Here it is in LV7.1
David
Edit: Ah there you perhaps gwd can help
Message Edited by David Crawford on 11-21-2006 01:53 PM
Message Edited by David Crawford on 11-21-2006 01:53 PM
Attachments:
Slide FFT to detect Frequency Changes.vi ‏94 KB

How can i display Waveform chart in a subpanel using Vi templates.

Hi All
I am new to Labview hence need some help. I am trying to develop an application which reads some data from a Wireless Sensor Network (WSN). The WSN consists of base station connected to the USB port which recieves data from other sensor nodes. The data comes in a certain format. Node name, temperature reading, humidity reading etc. I want to read the data from the serial port and based on the Node name, i want to display the information for each node in s separate window or subpanel etc. So if a new node is detected then a new window is created for that node. Since all the nodes have the same sensors on board i only need a one template. I can read the data using the serial port, parse the data to detect which node it is and also what the sensor readings are. I have created a template VI for the sensor node. I am having problems in displaying the template VIs in a subpanel. I can succesfully display a Waveform graph in the subpanel but i am having problems in displaying a waveform chart in the subpanel. I can see the actual waveform chart in the subpanel, but i cannot see the plot. Would be greatful if someone could point out what i am doing wrong here.
Many Thanks
Raza
Solved!
Go to Solution.
Attachments:
template_graph.vi ‏16 KB
graph_template.vit ‏11 KB

Hi All
I think i have solved the problem. It seems like i was running the Vi in a loop. I have taken the Run Vi outside the while lopp and this works fine. Also i need to close the reference at the end.
Raza

How can i print out the waveform chart?

hello everybody,
how can i print out the "waveform chart". can i do it just push the button. ( example; stop button is stop the program etc..)
i checked the NI examples but i can't understand. i'm new to the Labview.
pls help me.
i added the my program
look forward your reply
regards from turkey...
Message Edited by hknmkt on 05-29-2008 04:15 AM
Attachments:
29.05.2008_11.vi ‏37 KB

hi jim,
i tried the program but it's not running. When i run the program, it's print out without run the program
i added the printed file.
look forward your reply
hakan
Attachments:
error8.JPG ‏8 KB

Display Data on waveform chart or XY graph over a long period of time

Display Data on waveform chart or XY graph over a long period of time
Can anyone help?
I am acquiring data from an Ni DAQ card with the following parameters - sample rate = 12800, number of samples = 4096. I want to extract order information so as to track changes in the amplitudes of certain frequency harmonics. So I use the sound and vibration toolkit to extract this information as shown in the attached Vi. I will like to plot the resulting amplitudes against real-time starting at the time the Vi was run. I really want the display to show these changes over long periods (eg. days, months and even years).
Problem.
I have tried to plot the Y component of the resulting magnitude for a given order on a waveform chart. My choice of the waveform chart is because I also want to display alarm limits (using the mask and limit vi) (I can't have these lines displayed on an XY graph plot). I tried adjusting the scale offset using the property node and setting the offset to current time. However, the display on the X-axis can only show a span of 2 minutes as will be seen when you run the attached vi. I want the time display on the x-axis to be over a period of days, months and even years. Is there a way to set the maximum scale on the x-axis to be say a year or so in future.
I really want the display to be like the one in in the second attachment.
Attached is a sample VI created using an Ni USB 9234 DAQ card. Any card will do but I am only getting the signal from one channel for this example
I will appreciate any help that can be given to me.
Thanks
Attachments:
Real-Time Graph Display.vi ‏170 KB
Sampe screen1.doc ‏37 KB

Long term testing can be tricky- and we'l get into that later. Lets start with the basics that you have wrong.
The vi as you have constructed it has only one memory element, the chart history length (default is 1024.)
You can change the number of points the Chart will remember by Right-clicking the chart an select Chart History Length from the menu.
But for a long term test - and one where you want to REMEMBER the first value you need a memeory element that is independant of the application. Your PC WILL loose power or need to be rebooted eventually. Heck it might even need to be replaced! you really need to store your data in a file. Preferablly in a file that is backed-up on a regular basis so you don't lose every point of data if the PC dies. It realy hurts when you have to restart a 2yr test because you've lost the 18months of data you collected.
For an application like this I would seperate my "collection" and "Evaluation" operations.
Have one vi that takes the reading and writes it to a file at a configurable rate You may want 1reading per minute for seveal days then 1 per hour for a few weeks- then maybe only once or twice a week for the next couple of years since you are looking for LONG TERM stability. having too much data to evaluate can take a lot of digging to find the few things that interest you (but always take more that you think you need)
Have another utility that COPIES the files, reads them and displays the data you are interested in that day. The data you want to look at won't change over time HOWEVER, you WILL want to analize it in different ways depending on what the data trends look like. Having seperate routines for collection and display allows you to update the display style and analisys without even stopping the collection vi (much less editing the vi)
Jeff

How can I display more than 1 loop iteraction in a waveform chart?

Using DAQmx, I am inputting a signal at a rate of 10k with 1k samples inside a while loop. I want the first 3 seconds of data to display on a waveform chart without having to change the rate or number of samples. Is there a way to stop the waveform chart from clearing after every loop iteration so that I can display more than 0.1sec of data? Thank you for any help you can provide!

The default history length of a chart is 1024. To make it longer is a right click option.

How do I add a time stamp to the moving "Major Grid Lines" of a Waveform Chart?

Hello
I am using LV 8.5.1
I am using a Waveform Chart and I have turned on the "Major Grid LInes" using the properties tab of my waveform chart. (properties-->scale->grid lines)
When the code executes, I want to attach a time stamp to each moving yellow grid line.
So as the grid lines move from right to left, there is an associated time stamp for each.
Can someone help!
thanks
J
Solved!
Go to Solution.
Attachments:
how do I add time to the yellow grid lines.vi ‏16 KB

hova2010,
If you right click on your graph and go to X Scale >> Style >> and then choose one of the 3 styles on the far left you shoul see timestamps for those grid lines.
Ben Sisney
FlexRIO V&V Engineer
National Instruments

Combining 2 readings into a waveform chart/graph displaying continuous readings of data from different sources

Hi,
In the file
(Serial Read and Write to .tdms & Compare on Graph – test.vi) I am trying
to integrate the following two waveforms into a single waveform: Realtime
reading and Waveform chart (open vi to see). Both of them display speed vs time
but from different outputs. One comes from an excel file (Teraterm – Results.xlsx
– sheet 4, (column 3:row 4) to (column 3:row 1878)) and the other comes from
the Serial input which is in Hex format and is split to get the various readings
of speed, voltage etc. I have already wired speed to a variety of waveform
outputs, but all result in broken wires.
The readings are taken in by the program
and but I am unable to wire the two readings together into one graph.
Please do let me know as to how can I make this work.
Thanks in Advance.
Best Regards,
Akhil
Kumar Meesala (Mr.)
Year
4 | Undergrad | Mechanical Engineering
National
University of Singapore
Email:
[email protected]
Mobile:
(+65) 9326 7069
Solved!
Go to Solution.
Attachments:
Serial Read and Write to .tdms & Compare on Graph - test.vi ‏58 KB
Teraterm - Results.xlsx ‏593 KB

Dear GerdW,
I'm sorry again about the misspelling your nick.
I tried connecting a waveform chart to the two terminals (speed from the DAQ and speed from the excel file) but I was unable to get the connection right. I understand that charts are used for readings which are equally spaced out, whereas XY graphs are used when the readings are not be spaced out uniformly. But I am unable to wire the connections correctly.
Actually the DAQ device continuously sends out data through the serial port. So I would not run out of data . Are you referring to the data coming from the DAQ device or the excel file? I actually have not thought of what would happen when the excel file would run out of values I am just hoping for the software to run till then for now
I have cleared up the wires as well Thanks for your help.
Best Regards,
Akhil Kumar Meesala (Mr.)
Year 4 | Undergrad | Mechanical Engineering
National University
of Singapore
Email: [email protected]
Mobile: (+65) 9326 7069
Attachments:
Get Excel Values.vi ‏25 KB
read_excel_values.llb ‏201 KB
Serial Read and Write to .tdms & Compare on Graph - test.vi ‏79 KB

How can I change the color of plot in a waveform chart and graph?

There are 4 plots in a waveform chart, from plot0 to plot3, and I want to chang the color of plots dynamicly up to my needs when the VI is running.
For example, as show in the picture, i want to set the plot0 as RED, and plot1 is BLUE, plot2 is YELLOW, plot3 is GRAY.
If there is only one plot, i can change it's color, however when there are more than one plot, it fail.
How can I do it?
Thanks
Attachments:
waveform.JPG ‏61 KB

Hello MilkyStone,
first you have to set the active plot, then change its color (or other properties). All that is done using property nodes.
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

How to take the print out of the entire data from the waveform chart

i am using cont acq to spreadsheet file.vi to acquire data from a number of channels. this vi also plots the acquired data on the waveform chart. i want to take the print out of the entire data. how can i do it ?
also how can i take print out of the data between given interval??
please reply me
thank you

There are a number of different ways of achieving your goal. Depending on which version of LabVIEW you have and which development environment, the Report Generation Toolkit is a very powerful tool. Attached is an example that prints the acquired data without the use of additional toolkits.
Jonathan Hildyard
Applications Engineer
National Instruments
Attachments:
DAQ_with_Print.llb ‏115 KB

How can I show only the function that I desire in waveform chart?

Hi, I have a Waveform Chart that shows 3 CHart.
If I go to the Property Node of Waveform Chart I can choose "Plot Visible", but this command give me the possibility to delete only third chart.
How can I do to put 3 Bolean Controll to choose to see one, two or 3 chart or maybe nothing?
Thanks,
Vanny
Sweet, Beautiful and Young Female Physicist (SBYFP)
(I speak a not very good english, so If U are Italian LabVIEW expert speak in Italian, if U speak in Eglish... please speak easy )
My e-mail for personal contact: [email protected]_NO_SPAM_PLEASE

Something like this would work too.
Tim
Johnson Controls
Holland Michigan
Attachments:
Example.vi ‏18 KB

Saving array data from a waveform chart

I am using a CRIO 9004 and a 9237 bridge module to measure some strains from strain gauges. I've got one timed loop that reads the DMA FIFO and puts the arrays of values (16 data points, 4 per channel) into a queue. In the consumer timed loop a For loop scales the binary data, auto indexes it into arrays, then the arrays are merged into a 2D array for the four channels displayed on a waveform chart . Everytime the consumer loop runs it indexes 4 data points (per channel) yet the waveform chart plots them in a consecutive manner and doesn't overwrite the previous four. If I convert the arrays to waveform arrays I don't see anything on the waveform chart.
If I pass the 2D array of data to a array indicator inside or outside the consumer loop I get only 16 data points. I want to save the information that appears on the waveform chart after the consumer loop but because I'm not using waveform data type I can't use the write waveforms to file vi. The waveform chart history buffer has been set to 195360.
Idealy we will run the four channels for 120 seconds charting the data and saving the data. The minimum data rate is 1613kS/s (403 per channel) The data can be saved after the loops have finished gathering and processing or while they are running. I noticed when I tried to write to TDMS it slowed the consumer down. Same thing if I use a shift register with the volume of data.
I suspect I'm not sending data to the chart in the correct manner ( usualy takes two attempts to "clear chart" using shortcut menu). I'm not too familiar with timed loops /producer consumer loops and just tried to put something together based on examples.
I've attached my host vi and front panel screenshot.

Hope they appear attached this time.
Attachments:
Basic DMA (Host).vi ‏444 KB
screenshot2.jpg ‏113 KB

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
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

Waveform chart-drop in pressure

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