Tdms files

Hi,
I have a PCI 6132.
I´m using a program to acquire datas in continuos mode, and save it in my pc.
I'm using TDMS files to record it. But this files are too long. I need record it in multiple files to make easy to read after.
Using just one file, it has more than 10Gb, so, I need make multiples files with 1Gb each one, for example.
Thanks,
Marcela

Hi,
I think the better idea is to write data into multiple TDMS files when streaming data, instead of split the file into multiple files when you finish writing.
There are at least several ways to split, it depends on your application. For example, if you have multiple groups or channels, you can read from the big one TDMS file group by group and write to new TDMS file for each group. And, you can read samples by samples, for example, if you have 1000 samples in the big one file and you can split the 1000 samples into 10 files and each new file contain 100 samples. Another way is based on TDMS file format, TDMS file is consist of "segments", you can divide the big one file into new files and for each new file, it contains at least one segment (it would be a little complicated for the implementation, you need to know where the segment starts from, etc).
Please refer to www.ni.com/tdms for more reference.

Similar Messages

Error reading TDMS file with inconsistend dt

Hello all,
I would like to ask your help to understand how to read a TDMS file which I am opening and closing based on a user input. As a result the data in the TDMS file does not have a consistent time step, which may be causing my problem, but I really don't know. I keep getting the error 2501, that I have an invalid reference.
Or, if I continue and bypass the error, the extract portion VI gives me an error stating that I need to define an integer multiple of dt.
I am not sure how to solve the first point as I have the reference wired directly to the read TDMS vi.
I have attached a screen shot of the error and the portion of the VI with the offending error (it is the code connected to the read TDMS read vi).
My goad is to extract a portion of the data to do calculations on and display a result to the user.
thanks for any comments.
A. Lopez
Attachments:
error-2501.JPG ‏198 KB

I think you open multiple times the same TDMS file, you should open it before the while loop. And I don't see a close tdms function...
Also check for errors on the open TDMS function.
Ton
Message Edited by TonP on 02-14-2007 07:45 AM
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How can I open a tdms file and replace a subset of data then save that change without re-writing the entire file again?

Hi all,
Is it possible to open a tdms file and make a small change an an array subset then save the file without having to save the whole dataset as a different file with a new name? That is to say, is there something similar to "Save" in MS Word rather than "Save As"... I only want to change a 1D array of four data points in a file of 7M data points.
I am not sure if this make sense? Any help is apreciated.
Thanks,
Jack

You can use either one, but for your application, I would use the synchronous. It requires far less setup. When you open the file, set both enable asynchronous and disable buffering to FALSE to enable you to use synchronous with arbitrary data sizes.
Attached code is LabVIEW 2011.
This account is no longer active. Contact ShadesOfGray for current posts and information.
Attachments:
UpdateTDMS.zip ‏20 KB

How to get the last data point from a TDM file in LabVIEW?

Hello,
I am using LabVIEW to analyze some rather large TDM files, and I need a way to get only the last data point. So far, the only way I have been able to accomplish this is by reading the entire file. Is there a property in the TDM file or a function in LabVIEW that will allow me to get the index of the last item in a channel?
Thanks!
Christina

Do you want to avoid reading whole file and want to be able to reach or get the index of last value of channel? is there any specific reason? I am not sure you could do it without loading the whole file. But the easiest way would be just to use array functions "array size" would give you the index of last element.
-Nilesh
Kudos are (always) welcome for the good post. :-)

Newly written tdm/tdms file not found

Hi,
I am trying to save some simple thermocouple data to a tdm/tdms file. I run my vi and it seems to work just fine. I am using the NI 9213 getting started example as a basis and have added tdms open, tdms set properties, tdms write, and tdms close. I can see the data streaming on the waveform chart but when I hit stop and go look for the saved file I can't seem to find it. What am I doing wrong?
Thank you
Solved!
Go to Solution.

SRamirez wrote:
I set it to create. When I run it once for a new folder it runs just fine but if I try again I get error 6.
You are specifying a folder? You should be giving a full file path (like c:\temp\blah.tdms). What you might want to do is build a file name based on the data/time. This way you won't have to worry about overwriting files and what not.
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Attachments:
Build File Name.png ‏9 KB

How to compare signals from two different .tdms files?

i'm developing a lie detection system in labview.so inorder for that i need to compare the threshold physiological signals from the .tdms file with the signals i acquire continuelsy from the subject for each question asked.i use respiration monitor and heart beat monitor together with the sensorDAQ to acuire the physiological signals.so which are the function i should make use of?i have the following toolkits
1. advanced signal processing toolkit
2. adaptive filter toolkit
3. digital filter design toolkit
4. biomedical toolkit
please give me advise on this.
thank you.
Solved!
Go to Solution.

Lie detector systems (polygraphs) generally work by looking at the physiological responses to the own subjects baseline, and do this in real-time. You could use a file that represents the stored "baseline" for the subject, but the overall environment, circumstances, general state of the subject, etc. may not be similar enough to easily see subtle changes.
From the stored file, you might determine a set of parameters or thresholds that indicate "normal, relaxed" for each signal. You could read the file into your LabVIEW program, process each channel, and save these parameters. Then when you have the new data, you can read the new data file in and process it in a similar way and then determine whether the parameters are outside the limits that you established for a "lie".
You may get more responses to this question if posted in the Biomedical User Group
Visit the NI Biomedical User Group at:
www.ni.com/biomedusers

How do I select more then one channel to view in tdms file viewer graph panel

I have a TDMS file that I can view with the labview 2013 TDMS file viewer and I can select one signal out of 15 signals to view on the graph panel. however I would like be able to look at 2 or 3 signals
on the same graph but can't seem to be able to select more then one signal at a time. Is there a way to select more then one to view?

I've modified the TDMS viewer in the past to allow selecting multple channels. It's a little bit of a pain because the tree control in the viewer only allows you to select one item. You have to edit the tree to allow multiple items. Now your selection is an array instead of a scalar. This means the rest of the code has to be updated, and the references to the tree in subVIs need to be updated. Not impossible but it takes some time. Alternativly open it in Excel with the free add-in then you can select the two columns you want and insert a graph. Not as simple for the user but using Excel, which users should be familiar with might mean users need less training on data files.
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How does DIADEM import TDMS files? How gets every channel his number and groupindex? How can I determine which channel has which groupindex and number?

I store different channels in a TDMS file.
I like to have a time channel at the first position with group index 1 and number 1.
When I read the TDMS file with DIADEM the time channel (Float64) is on a differernt position, and the channels are not sorted alphabetically.
Here are my questions:
How does DIADEM import TDMS files?
How gets every channel his number and groupindex?
How can I determine which channel has which groupindex and number?
Best regards
Joerg

Hi Jörg,
i suppose that you´re programme whose create the *.tdms file is writing on false position. Try to create datas with timechannel on first indes in diadem, then save it and then open it again. you see that all is correct. So please tell me what programm in what version do you use and please attache it here.
Did you use the library for creating *.tdms files like in the link ?
http://zone.ni.com/devzone/cda/tut/p/id/6471
Here you find the gtdms_8.x.zip - when you extract it and opened the *.llb you find vi´s for all functions e.g. writing 2d array of strings to *.tdms file
when you open the subvi´s then you see how created and writing datas/structure to *.tdms files. Because *.tdms is binary you can´t see structure with open it in editor.
When you don´t have Labview you can use the 30 days test of current version 8.5 under following link
german version download link
https://lumen.ni.com/nicif/d/lveval/content.xhtml
english version download link
https://lumen.ni.com/nicif/us/lveval/content.xhtml
Hope it helps
Best Regards

.tdm file storage vi's slow editing vi's

I am developing software using Labview 8.5 and have recently added some file storage vi's for the .tdm format for use in DIAdem 10.2. Upon using the open storage, set file properties, write channel group, write channel, and close storage vi's, the editing has become extremely slow - for any operation I try to perform there is a 10-15seconds delay before it occurs. If I remove the .tdm vi's from my diagram then the editing goes back to normal and changes/operations occur almost instantaneously as expected. My project is not large as far as I am concerned (Front panel - 121k, block diagram=1538k, code=0.2k, data=957k, total=2617k, total vi size on disk=389k)
I saw a similar post to the .tdm storage vi's causing this to occur back in 2005 and was supposed to have been on the fix list but it does not appear that it has 3 years later. I am sure many others are using these vi's so not sure what I may have done differently to cause the editing to slow down so much.
Anyone with ideas and fix would be greatly appreciated as I cannot afford to sit around 10-15 seconds for every step of my developement.

Yes, sometimes Storage VIs are slow. But They are Express VIs, supplying the easy configuration for users. If you feel they are too slow, I suggest that you can use TDMS files instead.

Tdms-files: Is it possible to prevent LabVIEW and DIAdem from creating .tdms_index files?

Hello,
is it possible to prevent LabVIEW and DIAdem from creating .tdms_index files when opening/creating/editing a .tdms file?
I think I have no benefit from the .tdms_index files because our applications create a lot of little .tdms-files (repeat measurements). With the additional .tdms_index files we have unnecessary memory consumption and it takes longer for Windows to open the containing folder. Also it´s confusing when searching for a certain file.
Best Regards
Daniel
Solved!
Go to Solution.

Hi Baui,
I'm afraid there's a direct way to disable creating .tdms_index file now from LabVIEW and DIAdem. You can use TDMS Advacend API in LabVIEW, which doesn't create any index file, or you can just make some simple programming and delete the .tdms_index file after closing the TDMS file.
This is a request for a long time, we'll consider to add this feature for TDMS in future releases.
Yongqing Ye
NI R&D

Reducing TDMS file size?

Hello,
I'm streaming analogue data acquired at 32 kS/s to disk in 32768 data point writes using TDMS Write.vi .
A while back I feel that I saw an article about reducing the size of the TDMS files with some tricks. I think one of them might have been not writing unused high significance bits(?).
I can't find that article now and I"m wondering if anyone had suggestions for reducing file size? Right now its about 0.25 MB/s. This is manageable, but it would be nice to reduce this if it were easily possible.
Thanks in advance,
Frenk

Hello,
Hmmm... I've run into an unexpected problem. I'd like to scale the unscaled data from DAQmx for some calculations during the data collection, but it isn't scaling the way I would have expected.
My range is +/-10V and the largest unscaled numbers for data filling that range are very roughly about +/-125000. I would have expected them to approach 2^31 (one bit for sign)!! How can one scale this data?
Also, my saved TDMS file doesn't seem to have the information that "Cont Acq&Graph Voltage - Graph Unscaled Data from File (TDMS).vi" needs to scale it.
Regarding I16, my data is unusual in that it contains a signal of interest that is about 80 dB below the stimuli that are also in the measurement. For that reason I need the full I32 to avoid excessive quantization error in the signal of interest.
Thanks again!
Frenk

I write digital port by 'DAQmx Configure Logging.vi' and receive TDMS file with 8 boolean channels. How can I write to 1 integer channel?

Hello!
I want to write 1 digital port from PXI-6536 with streaming to TDMS file.
I'm writing by 'DAQmx Configure Logging.vi' and become TDMS file with 8 boolean channels.
How can I write to 1integer channel?
Attachments:
1.JPG ‏27 KB

Hey Atrina,
The actual data stored on disk is just the raw data (that is, a byte per sample in your case). It's really just a matter of how that data is being represented in LabVIEW whenever you read back the TDMS file.
I'm not sure if there is a better way to do this, but here is a way to accomplish what you're wanting:
Read back the TDMS file as a digital waveform. Then there's a conversion function in LabVIEW called DWDT Digital to Binary. This function will convert that set of digital channels into the "port format" that you're wanting. I've attached an example of what I mean.
Note: When looking at this VI, there are a few things that the downgrade process did to the VI that I would not recommend for these TDMS files. It added a 1.0 constant on the TDMS Open function, and it set "disable buffering" on the TDMS Open function to false; you can get rid of both of those constants.
Message Edited by AndrewMc on 01-27-2010 11:21 AM
Thanks,
Andy McRorie
NI R&D
Attachments:
digitalconvert.vi ‏13 KB

How to store data (in tdm files)

I'm looking for advice on how to store data in tdm/tdx files.
The main challenge is like this: At regular time intervals there is new data available (say every 10 minutes there are 10 minutes of new data available). All data is time based. So every ten minutes I may create a new tdm/tdx file containing this data segment. However, when i want to analyze the data i dont necessarily want to view 10 minutes of data from all channels, but maybe 20 hours of data from one particular channel.
The way I've achieved this so far is to manually load each 10 minute segment of this particular channel and then add these parts together. This is both time consuming and cumbersome. Is there a better way to do this that I've simply not discovered yet? Is there a better way to store data to simplify this process?
One solution is of course to save data from several 10-minute frames in one file, but seeing as there is a never ending supply of data i cant simply save all data in one giant file, it has to be split up at some point, and the problem will still remain.
One factor to have in mind here is that this is rather large amounts of data (maybe 10GB each day), so the option to simply load all the data into memory goes out the window rather quickly.
Feel free to ask if I've not made myself very clear

Hi salte,
If your test ever ended, and if you had LabVIEW 8.20 or higher, I would recommend using a TDMS file, which handles data appeands flawlessly. DIAdem 10.1 now also does data reduction and index windowing during file loading for TDM / TDMS / DataPlugin files, so that you could easily load out only the part of the file you wanted to look at. But since you describe your data acquisition as never stopping and amassing 10 GB per day, I agree that it would be impractical to use only 1 data file. So we are stuck with some number of files which each contain a part of your measurement. This approach can have advantages, since you can save operational properties for each "buffer" such as average value, dominant frequency, ambient room temperature, etc., and later on you can use the DataFinder to query out only the data buffers which meet specific conditions based on these properties. The problem remains to load and assemble data based on multiple files. This is an old problem in DIAdem, and one for which I have an efficient and I hope satisfactory workaround application. It does what you describe already doing in the minimum amount of time and with the minimum amount of user interaction, and it can be highly parametrized to suit your particular situation. The ideal way to start the application would be as part of a ResultsList custom menu. This would enable you to query out the buffers you wanted, highlight those rows in the ResultsList, right-click and choose your custom menu, and WHAM! the selected buffers for your queried channel(s) are automatically appended together in the DataPortal. Launching from a ResultsList custom menu would mean that you could skip the file dialog and just read out the data sources directly from the ResultsList selection.
Let me know what you think,
Brad Turpin
DIAdem Product Support Engineer
National Instruments
Attachments:
Importing Data from Multiple DataPlugin Files.zip ‏198 KB

Read Measurement file does not read the first channel of my TDMS file

When I try to read a TDMS file with the Read Measurement File express VI, the first channel of the data is not there. When I open the file up in excel the channel exists

Even I have the same doubt regarding Labview plss help me reading the Excel file from 23rd row and the graph should be drawn between 1st column and 8th column , from 23rd row . Here is the sample data.
Attachments:
Book1.xlsx ‏204 KB

How to Read TDMS Files in Matlab in OSX

Using the example found on the NI website (http://digital.ni.com/public.nsf/allkb/0EEADA99DC7D00A4862572E30037C3A2), I am able to read my TDMS files into Matlab when using a PC. However, when I try to read them on my Mac, I receive an error:
??? There was an error loading the library "/Applications/MATLAB75/work/TDMS_files/dev/bin/nilibddc.so"
Error using ==> loaddefinedlibrary
dlopen(/Applications/MATLAB75/work/TDMS_files/dev/bin/nilibddc.so, 1): image not found
Error in ==> read_tdms at 21
loadlibrary(DLL_Path, H_Path);
My best guess for this error is the fact that Matlab operates through a Linux interface on Mac, which I found will open the file type .so and not .dll for this type of library. Is there some way to get around this in OSX and get it to read the .dll files? Or is there some way to get the libraries as .so files instead of .dll files?
Thanks for any help!
-Shelby

Shelby,
You may wish to look at a Matlab script another user wrote since they were having issues with NI's matlab support:
http://forums.ni.com/ni/board/message?board.id=170&view=by_date_ascending&message.id=318487#M318487
The script supposedly converts TDMS files directly in Matlab with no use of NI generated external DLLs. He was having issues because the NI tools hadn't been updated for the new version of Matlab.

How can I make a query by date with several TDMS files?

Hi,
I have a project that can write and read TDMS files everyday (a file for each day with date and time). There, I can import those files to excel (I choose a file and load it). But, I have a question: How can I make a query by date with those TDMS files? I'd like make a time stamp for start date and stop date, where I could compare the TDMS file dates and sum the values that are in the channels where these files are similar. For example, I save a file with "02/01/2013" name, in other day "03/01/2013", in other day "04/01/2013"... so, i'd like put in time stamp for start date "02/01/2013" file and to stop date "04/01/2013" file, than, sum all values that range with my TDMS files existing. How can I make that?
Thanks all,
Val

Hello Val_Auto.
You're Brazilian, no? Me too. = ^ - ^ =
I converted VI to version of your LabVIEW (8.5). Is attached in this reply.
This VI search all your TDMS in a range of dates and join them in a single TDMS. I hope this is what you wanted.
Query TDMS is the main VI. The TDMS VI Search changes the date format that out from calendar control (which is DD / MM / YYYY) to DD-MM-YYYY. This is because you can't name files using "/". I chose "-" but, if necessary, you should change to keep the same format of your TDMS files.
If you have any doubt as to its operation or how to make changes to adapt VI for your application, keep at your disposal.
Thank you for your contact; I hope have helped you and succeed in your application.
Wesley Rocha
Application Engineer
National Instruments Brazil
Visite a nossa comunidade em PORTUGUÊS!!!
Attachments:
Query TDMS.vi ‏62 KB
tdms search.vi ‏24 KB

Tdms files

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