Read from Measurement File to XY on Waveform Chart

Something pretty simple that is giving me a hell of a time right now.
I've got a .lvm here that has been saved from a DAQ and has one column of numbers starting from 0.0000 - 27.0000 in very small steps. The next column is amplitudes of the signal at the given time. Now, from this LVM file I'm starting a new vi and I want to read those values as X and Y and get them onto a waveform chart. As of right now I've tried hooking up "Read From Measurement File" and tried "Build Table" but that won't want to plug into a chart. Plugging the file directly into a chart causes two very different lines to show up but is no where close to what I'm looking for.
Any tips as to how to complete this?
Solved!
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Tasty,
More often than not I find Express VIs to be more trouble than they're worth. Here's an example of reading tab delimited data in from an .txt and plotting Y values versus X values on a graph. Hope it helps.
Andrew
Andrew
Attachments:
ReadData.vi ‏14 KB
data.txt ‏1 KB

Similar Messages

Read from measurement file (wrong values)

I have a VI where I save data using the ''Write To Measurement File utility''. When I open the .lvm file in the note pad I can see all the data correctly, but when I use the "Read From Measurement File" tool and try tho make a graph the data shown is not correct. Attached the .lvm file and one image of the chart that labview made using the "Read From Measurement File". If you open the lvm in the notepad you can see that the time column goes up to 22 sec. In the chart the time axis goes only up to 7,5 sec. What is going wrong??? Thanks
Ps: I changed the file .lvm to .txt to attach
Solved!
Go to Solution.
Attachments:
Chart.jpg ‏688 KB
teste.txt ‏156 KB

vitor22 wrote:
I tryed.
And how did it turn out? Saying I tried and not saying how it didn't work doesn't help me help you.
I was able to do it. But the X data wasn't correct. That is because your timestamps aren't regular spaced. So you can't use a waveform graph.
You need to use an XY graph. See the attached code for how to convert the two channels of data (time, your values) into a datatype to feed to the XY graph.
Attachments:
Example_VI_BD.png ‏49 KB

Read from Measurement File Express VI - Time information

I need some assistance with a small problem with building reports of collected data. I don't see it very relevant, but I'm collecting data from several modules on a 9074 cRIO. I'm not using the cRIO the way it is intended, but it is perfect for my needs. Anyway, I'm collecting the different types of data in RT, then using the express VI "Write to Measurement File" with TDMS option selected and one time column only selected. Also one header, etc. Nothing fancy.
In another VI I want to use this collection of .tdms files to create an Excel report. Everything is working good however I need a time column for reporting my data. When I view the .tdms file using Excel Importer, the time column is there and perfect, with the next column a relative time (or iteration) and then columns with the signal names at top and all the data below. Perfect.
I'm similarly using the "Read from Measurement File" Express VI to get the data back the same way it went in. I have everything in it's correct place on building the Excel Report, but I haven't been able to find any way to include the first time column in my import. I can use "Get Attributes" Express VI to get the signal names from the read, but that's not going to help with the time data. How is it possible that Labview allows to put the time data there, but not retrieve it? I'm aware of the warnings that Timestamps aren't supported by TDMS file format vs LVM, but there MUST be a way to retrieve that time information if "Excel Importer" can do it.
If that time column in the TDMS file is somehow computed using the start timestamp and dt, can someone explain how to compute that for my report?
Unfortunately, I can't use the LVM format because I need to allow the users of these VI's the backup of using Excel Importer to see this data if my report generation VI is not functional.
I'll attach one of the TDMS files for illustration. The first column of the second worksheet is exactly the data I need for my report.
Attachments:
TDMS Imported.xls ‏28 KB

DylanC,
Your solution works as needed. Thank You.
I think I found a better solution though. Apparently if you convert a signal from the Express VI "Read from Measurement File" into a waveform the time data required is included, then you can convert to a string with a for loop and insert it as a row header into a table. The result gives me what I need. I attached a screenshot if someone is interested.
AWyers
Attachments:
TableFromTDMS.JPG ‏61 KB

"read from measurement file" reads only first line of data

Hello,
I have a problem when trying to read a .lvm file through "Read from Measurements file" with the following block diagram
Problem: it reads only the first line of data from what I can see in the probe window,.
A part of the lvm file for reference.
I haven't used Labview in a long long time, I'm trying to figure out what I am doing wrong.
Thanks

Sorry meant to attach the lvm. Here it is. (Actually I had to put it in .txt because the forum wont let me upload a lvm file)
I unfortunately cannot share the full vi that record the data as I am not its owner/creator. I'll try to give as much info as I can with the relevant pictures attached, I hope it allows us to at least have an hint of where the problem might be.
(this is in a while loop)
In the stacked sequence, the other pannels are similar to the one shown here: value read fron a variable, converted to dynamic and a signal attribute is set. The "start recording" control operation is "switch when pressed".
Here are the properties of the set signal attributes
And here are the properties of the "write to measurement file"
Attachments:
NoTarget_full circle__Rx_-10-SAMPLE.txt ‏60 KB

Read From Measurement File... removes X Values of first column?

During one of our tests, two instruments were switched at the terminal by accident. I need to read in the massive lvm files, remove the wrong scaling and apply the correct scaling, while switching the values in the columns and right it all to new files. Simple right?
I wanted to use the Read from Measurement File.vi to make things easier, because the files are very large and I would like to analyze them 100 rows at a time. Some of the the files are around 1.5 Gigs in size so I need to read them in chunks.
The read from measurement file keeps removing the first column from the data! It outputs the data as a signal (dynamic data) and I have to use the dynamic to numeric array express vi. For some reason, before I even get to that point, the first column is not in the data.
No matter what settings I pick on the read from measurement express vi, the time column is removed from the data. I have checked/unchecked the "first row is channel names" and "first column is time channel" to no avail. The odd thing is that in the preview it shows the first column, as if it will read it properly... but it doesnt. Nothing I change in the settings can seems to make a difference in getting the first column, the x values, out of the file.
Below you can see the first column completely removed from the data.
This is extremely frustrating. By probing the signal out I can see the dynamic data attributes and the time column has already been removed, so I don't think that the signal to double array express vi is the problem, but I am not sure.
I am attaching my VI and a small data file to be analyzed. You can see what I mean.
The alternatives seem less than adequate. The read from spreadsheet file vi wants an offset of a specific number of characters not rows. The problem is that this is not constant between rows for some reason, when hidden characters are taken into account so I cant just set the number of characters in 100 rows and increment the offset in a loop... like I normally would. That means I might miss data or get a corrupted row.
This means that I have to use the read from text file, read how ever many characters I think a row is (over estimating a bit) then search for the newline character, find out how many chars are in that set and then offset that for the next loop iteration, all while converting each string number to a double. Talk about slow.
I have searched around and found that I am not the only one that has had this issue. This is a common thing, but no one seems to have the answer. Why can't the read from measurement file VI read all of the numbers in every row? Why cant I tell it I want a 2d array of doubles out and not a dynamic data type? It has to be something I am doing wrong.
Attached is a zip file with my VI and two data files. The "S19_A_DSI_detensioning_c.lvm" is the one generated by my VI (_c meaning corrected). "S19_A_DSI_detensioning.lvm" is the original measurement file. I hope you will pardon my messy VI, it's a quicky.
Any help you guys can give would be much appreciated.
[will work for kudos]
Attachments:
Scaling Factor Correction.zip ‏1109 KB

That is a great workaround. The help talked about putting a check next to "read lines" but for the life of me I couldn't find where to do that. I wonder what other VIs have mystery check options in the right mouse click menu. I mean normally options like those are inputs, I thought. I'm going to start right clicking on every VI I drop to see if there are options there I never realized.
I would still have to use the set file position VI and specify the byte offset right? How would I know where that is? I guess each character is a byte and I would count the characters in the string retrieved and then offset by that amount on the next iteration using a shift register?
While waiting for help, I ended up using the read from text file and using the match string to look for the new line character, and using the spreadsheet string to array vi, analyzed the files line by line. Thats just because I couldn't easily come up with a regular expression to get 100 lines. It was slow but it worked.
However, that still really doesn't answer the question of why it is impossible to get the first column with the read from measurement file express VI. Does anyone know? Is this a known bug?
[will work for kudos]

Data reading and writing problem? how to set " Read from Measurment File express.vi" 's readout datasize?

Dear all,
I want to use Labview to process a data.
Now I have a array in a text file.
this array is very very big. which is at least row*col = 6 * 100000;
the column size always 6,
but the row size is ramdom, some times is very big, like bigger than 65535,
when I use "read from measurement file express.vi" to read this file, the array I could get always 6*5339, I don't know why. the column size is always 5339.
and then I delete the 1st row of the array and then write into a txt file via "write measurement file express. vi", it takes a very long time. almost computer has no response. after a while, no file was creat to record the data.
is there an efficient way to process such big data file and store the processed file into a new file
thank you very much
Jack
Message Edited by weichengatech on 03-09-2006 12:00 AM

Hello,
There’s no real efficient way to read the file if you don’t
know exactly how many rows of data you have.
Your going to just have to read a row at a time and add the results to
the end of an array (granted for the clever programmers there are some more
efficient ways to do this than just with ‘build array’). I would start by asking you how much
information you know about the file and what the exact structure of it is (i.e.
is it a binary file, a tab delimited file, or a LVM file)? Could you provide a screenshot of the code
you are running? If you provide a little more information on the file structure
we might be able to contribute some additional information.
Look forward to hearing back from you-
Travis M
LabVIEW R&D
National Instruments

Read from measurement file problem

Hi all,
I am using the "Read from Measurement File" VI that is built into LV8. I am reading in a .lvm file consisting of 2 columns. I cannot seem to figure out how to index each column. When tested using a a single column data file, I am able to use the index array vi to access the data successfully. The problem occurs when I have 2 columns. To get around this problem I split my initial data file into 2 single column data file, but I would prefer not having to do this. Is there anyway to avoid this?
When I read the 2D file into an array I can only index the data located in the 1st row 1st col and the data in the last row 2nd col.
The array size function results in the value "2" yet each column has 201 entries.

Attachments:
Write to LVM.vi ‏128 KB
To read LVM.vi ‏70 KB

Labview 8 crashes when using Read Labview Measurement File

Hi All,
I am a new user for Labview. I installed Labview 8.0 from the CD (evaluation copy). I was just testing the sample code provided by NI. I opened the "Load from File and Display" example and I was trying to open the properties for the Read Labview Measurement File component when Labview crashed. I tried it a couple of times and everytime it happens the same way (when I double click the component or right click on it).
I am using Windows XP with all the updates done. In the Windows crash report, the application version is 8.0.0.4005.
Other problem I encountered is a missing component on the Input Palette (no DAQ Assistant present) and the Instrument I/O Assistant raises the error "Measurement & Automation Explorer or the Instrument I/O Assistant is not installed correctly. Please install these from the Labview Driver CD". For the last problem, I will try to run the Labview Driver CD, once I get it. But I am not sure if the DAQ Assistant will show up then or not.
Any ideas?
Regards,
Nick

Hello Nick,
While it is not my area of expertise, I would expect the DAQ Assistant would appear after installing the driver CD as you said you would be trying.
What caught my attention was the crash. The easiest way to resolve the crash is to delete the instance of the Read LabVIEW Measurement File on the diagram and place a new one from the Express Input palette (now called "Read From Measurement File"). In that situation, I would expect just pressing OK to accept the default configuration should work. The crash occurs in certain circumstances when the Read / Write Measurement File Express VIs are dropped from a previous version of LabVIEW and then their config page is opened in 8.0.x. This issue should be resolved in a future release, sorry for the inconvenience.

How to open saved files using 'read from text file' function

Hi everyone, I am having a hard time trying to solve the this particular problem ( probably because I am a newb to lanbview ). Anyway , I am able to save the acquired waveforms by using the 'Write to text file' icon. I did manually modify the block diagram of the 'Write to text file' icon and create the correct number of connector so as to make my program work. But now I have no idea on how to modify the block diagram of the 'Read from text file' block diagram to make my program 'open' my saved waveforms. Or i do not have to modify anything from the block diagram of the 'Read from text file'? Can anyone teach/help me connect up? Do i need the build array on the "open" page?
Here are some screenshots on part of my program
let me know if you guys would need more information / screenshots thank you!
Attachments:
ss_save.jpg ‏94 KB
ss_open.jpg ‏94 KB
modified_writetotextfile.jpg ‏99 KB

Ohmy, thanks altenbach. oh yeah i forgot about those sub VIs. will upload them now. Was rather demoralized after reading the comments and really struck me on how weak i'm at on labview really hope to get this done. But of course i have to study through and see how it works. Actually i am going to replace those 'signal generators sub vi' with ThoughtTechonology's sample code so i can obtain data waveforms real-time using Electrocardiography (ECG) ,Electromyography (EMG ) and Electroencephalography (EEG) hopefully i can find out how to connect the sample code.
( ps . cant connect it now unless my program is working otherwise labview will crash )
( p.s.s the encoder of my biofeedback trainer already acts as an DAQ so i wont need to place an DAQ assistant in my block diagram i suppose )
The sample code of ThoughtTechnology is named as attachment.ashx.vi. too bad i cant use it and present it as my project
Attachments:
frequency detactor.vi ‏53 KB
signal generator.vi ‏13 KB
attachment.ashx.vi ‏40 KB

Read from spreadsheet file

Hi! I am a beginner labview user and I have a problem reading data from a
..xls file. I have written in columns the data that i want to present in a
waveform graph through labview. I give the path to the Read From Spreadsheet
File tool and i connect a true constant in the "transpose" terminal. The Run
button shows me no error but all I get in my waveform graph is a x-axis
line. Could someone help me? Thanx

You say that you want to read data from a .xls file. You use Read From Spreadsheet File to get the data into LV.
You have mixed some things. A .xls file is NOT a spreadsheet file. It is a file which could be read by MS Excel and some other tools which have import filters for this file. Read from Spreadsheet File is not such a filter.
A spreadsheet file in the context of LV is a text file where the cells of a row are separeted by a tab and the rows are separated by a end of line.
A save thing is use Active-X automation to communicate with MS Excel. Let it load the file and read out the cells. The are examples in LV help and in the dev zone. You must have installed and licenced MS Ecxel on your target machine. Maybe someone has written such a fil
ter for LV but I don't know it.
The other way will only work if you use US local settings and the data is in one worksheet. Save the file with the extention .txt. So Excel will generate a text file of the correct format. Excel will use the regional settings of your machine. You can read in this file with Read From Spreadsheet File. Unfortunatly this will use fixed settings which are the same as for US regional settings.
Waldemar
Waldemar
Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
Don't forget to give Kudos to good answers and/or questions

For Mike Porter: Read from Spreadsheet File.vi" function

On 2/17/03 you answered my question about reading and viewing a test done last week back into Labview. I can open the "Read from Spreadsheet File.VI" in Labview and read the file "data.txt" into the VI. The data comes back into the rows & cells on the VI screen but I don't know how to open the graph to see the data as curves. I can see about a 3 x 4 array of cells at a time and the correct data is there but I want to plot it. Do I need to create a new block diagram and VI? I apologize for the vagueness of my question - I'm new at Labview.
Attachments:
DATA2.TXT ‏183 KB

Create a VI with a Waveform Graph on the front panel. On the block diagram, insert a Read From Spreadsheet File function. Connect the All Rows output to the Waveform Graph.
Attachments:
Graph.jpg ‏3 KB

UPDATE : Toshiba Recovery Wizard 'cannot read from source file or disk' error (satellite L500)

UPDATE 2: Phoned Toshiba tech support again, guided by techie to begin the recovery again. Just before phoning I was able to go into recovery options and view the drive setup and all the files that couldn't be read are on the CD so I've no idea why the error kept occuring, and neither did the techie. Fingers crossed it works this time but I'm not overly hopefully given that we've just done exactly the same as I did before. UPDATE 1: I got into the BIOS and reset everything back to defaults and yay, my toshiba recovery wizard now starts! :-D On the down side, when trying to do a factory default software / out of the box recovery I continually get error messages with regards to copying the files, for example
cannot read from source file or disk
7z.dll
Type application extension
size 585kb
date modified 7/14/2009 10.26pm
other read / copy errors include PREINST6.SWM, BOOT_32, BOOTPRIORITY, CHECKMAXPTSIZE, CHGBOOT, CPU, CPUCHECK, CREATEPARTITION, CTRLDRVINFO, DISKWIPE, DMI, DPINST32, EBLIB.DLL, ERRORDIALOG, EW3BOOTSEQ, FWLINK, FWLINK.SYS, GETHDDINFO, GETKEYSTATE, IMAGEX, INFILED, INITRECAREA, KRAIADAPI.DLL ..... at which point I decided to 'skip all' :-/
Any explanations as to what's going on and how I might be able to fix it would be very much appreciated! :-) Thank you!
I have a two and half year old satellite L500 with an Intel i-3 and 4 gigs of RAM, on which I was running Windows 7.
Admittedly it’s had rather a hard life (I ran some very demanding CAD / graphics software on it) but it had always performed well until just recently, when after suffering several BSOD (which had never happened before), the hard drive failed.
I partitioned and formatted a brand new hard drive (which is perfectly fine and functions normally when hooked up to another laptop with a SATA to USB cable) and obtained system recovery discs from Toshiba. Unfortunately, when I try and run the first disc, windows starts to load files but then generates an error screen with the message Error F3-F100-0003 and a request to turn the computer off.
When I use the windows Memory Diagnostic to get into the Windows Boot Manager Screen I get the following;
Windows failed to start. A recent hardware / software change might be the case.
To fix the problem
Insert your windows installation disc and restart your computer
Choose your language settings and click ‘next’
Click ‘repair your computer’
File: \boot\memtest.exe
Status: 0xc000000f
Info: the selected entry could not be loaded because the application is missing or corrupt.
I can also use F8 on startup to get into the advanced boot options but selecting any of them simply results in the F3-F100-0003 error message. I’ve run a memory test using the UBCD, which tells me the memory is fine, and tried another hard drive (which also works perfectly well in another laptop) but no joy. On phoning Toshiba support the techie said my hard drive had failed, but as I say, both hard drives are perfectly fine / usable when hooked up to another laptop. I’m now completely stuck as to what the problem is and how I might resolve it – any advice / suggestions would be most gratefully received! Thank you in advance :-)

Satellite L655-S5096
Downloads here.
the second disc gives me the the "cannot read from source file or disk PREINST8.SWM"
My best guess is that the disc is not readable. Try copying it to another. Sometimes that works.
Otherwise, order new discs from Toshiba.
-Jerry

Cannot delete itunes from pc,message states. a network error occurred while attempting to read from the file C:\windows\installer\itunes.msi

ITUNES WILL NOT DELETE FROM ADD @ REMOVE PROGRAMS,
MESSAGE, READS a network error occured while attempting to read from the file C:WINDOWS\installer\iTunes.msi

All sorted now just needed to repair itunes from control panel

Why does Read from Text file default to array of 9 elements

I am writing to a text file starting with a type def. cluster (control) of say 15 dbl numeric elements, that works fine I open the tab-delimited text file and all of the elements appear in the file. However when I read from the same text file back to the same type def. cluster (indicator), the read from text file defaults to 9 elements?? Is there a way to control how many elements are read from the file. This all works great when I initially use a cluster of 9 elements and read back to a cluster of 9 elements.
Solved!
Go to Solution.

From the LabVIEW Help: http://zone.ni.com/reference/en-XX/help/371361G-01/glang/array_to_cluster/
Converts a 1D array to a cluster of elements of the same type as the array elements. Right-click the function and select Cluster Size from the shortcut menu to set the number of elements in the cluster.
The default is nine. The maximum cluster size for this function is 256.
Aside: so, how many times has this question been asked over the years?

LabVIEW for ARM 2009 Read from text file bug

Hello,
If you use the read from text file vi for reading text files from a sdcard there is a bug when you select the option "read lines"
you cannot select how many lines you want to read, it always reads the whole file, which cause a memory fault if you read big files!
I fixed this in the code (but the software doesn't recognize a EOF anymore..) in CCGByteStreamFileSupport.c
at row 709 the memory is allocated but it tries to allocate to much (since u only want to read lines).
looking at the codes it looks like it supposed to allocated 256 for a string:
Boolean bReadEntireLine = (linemode && (cnt == 0));
if(bReadEntireLine && !cnt) {
  cnt = BUFINCR;    //BUFINCR=256
but cnt is never false since if you select read lines this is the size of the file!
the variable linemode is also the size of the file.. STRANGE!
my solution:
Boolean bReadEntireLine = (linemode && (cnt > 0)); // ==
if(bReadEntireLine) {    //if(bReadEntireLine && !cnt) {
  cnt = BUFINCR;
and now the read line option does work, and reads one line until he sees CR or LF or if the count of 256 is done.
maybe the code is good but the data link of the vi's to the variables may be not, (cnt and linemode are the size of the file!)
count should be the number of lines, like chars in char mode.
linemode should be 0 or 1.
Hope someone can fix this in the new version!
greets,
Wouter
Wouter.
"LabVIEW for ARM guru and bug destroyer"

I have another solution, the EOF works with this one.
the cnt is the bytes that are not read yet, so the first time it tries to read (and allocate 4 MB).
you only want to say that if it's in line mode and cnt > 256 (BUFINCR) cnt = BUFINCR
the next time cnt is the value of the bytes that are not read yet, so the old value minus the line (until CR LF) or if cnt (256) is reached.
with this solution the program does not try to allocate the whole file but for the max of 256.
in CCGByteStreamFileSupprt.c row 705
if(linemode && (cnt>BUFINCR)){
cnt = BUFINCR;
don't use the count input when using the vi in line mode. count does not make sense, cnt will be the total file size. also the output will be an array.
linemode seems to be the value of the file size but I checked this and it is just 0 or 1, so this is good
update: damn it doesn't work!
Wouter.
"LabVIEW for ARM guru and bug destroyer"

Read from Measurement File to XY on Waveform Chart

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