Write to Measurement File time column wrong starting value

I am using Write tp Measurement File express VI. I select to write one time column. The values writtent in the time column start from a value that does not seem to correspond to anything in the program -- sometimes as much as 2-3 days before the saving begins.
Can I force the starting value of time to something, or get it to write the time since we started saving, or something predictable?

Include code whenever available. Asking somebody to troubleshoot your software without any code is like asking your mechanic to fix your car without taking your car to him.
Source
I don't recommend using the Write Express VI. I recommend using the File I/O primatives because they allow for much more control over what gets written and how. Still I would expect the Express VI to be able to write time properly so I'd assume there is some kind of bug with the data being given to the function. Post some code so we can see what is going on.
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Write to measurement file, adding column name in text file.

Hello,
Is it possible to add own column name for a text file using Write to measurement file function?
In the created file I have three different columns (I want to name them Time/Voltage/Date&Time).
Maby I should choose different write option like write to spreadsheet?

You are going to have to post some actual code if you want us to help here. Otherwise it is a complete shot in the dark. Posting an example CSV file of what you have and what you want would also be beneficial.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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"write to measurement file" specify column names

I'm using "Write to measurement file" VI to create a TDMS file from 2 and possiby more data sources. Currenty the columns are titled "Untitled", "Untitled1", etc. I would like to specify column names. Can anyone point me to an example or tell me how to do this?
Thanks,
Ron

Hi,
I've done some project with TDMS a few times and you can wire the column names (channel names) to the VI. See attachement
Kind regards,
- Bjorn -
Have fun using LabVIEW... and if you like my answer, please pay me back in Kudo's
LabVIEW 5.1 - LabVIEW 2012
Attachments:
TDMS.JPG ‏24 KB

Write to Measurement File: Time has minutes and seconds. Where are the hours?

Hi,
I have dynamic data acquired by Express VI: DAQ Assistant from a CompactDAQ and wired to Express VI: Write to Measurement File. In the resulting text file in the header the Date is recorded correctly in DD/MM/YYYY format. The Time field should be formatted HH:MMS.XXX but all I see is MMS.XXX. Is there a setting I should change to see the hours?
Regards,
Andrew.

Found the answer, sorry. Excel formatting issue. Not LabView after all.
Please delete this thread.
Cheers,
Andrew.

Write to measurement file loses timestamp data in tdms format

Hello all, I'm using the Write to Measurement File expressVI and I have created a loop in order to be able to individually label the column headers for each data signal that I'm writing. However, while the loop is successful in doing this the resulting TDMS file that the expressVI creates ends up losing the timestamp data that is used to record the time for each row and just writes a '0' instead. The timestamp data is present before the loop that adds column headers, which I have verified by adding an expressVI just before the loop. Please see the attached code for clarification.
How do I regain the timestamp info after the for loop executes and adds column header info? Thank you.
Attachments:
Write to measurement file specify column name.vi ‏106 KB

The problem with Express VIs and with the Dynamic Data wire is that they (almost) complete obscure what is being done "under the covers". They manipulate data in ways that are unseen and often unexpected. While they allow beginners to do extremely simple tasks quickly, they can easily lead to situations such as you are discovering.
If what you want to do is to write a TDMS data file, you should probably investigate the TDMS functions on the File I/O palette. I've not used TDMS myself, but I know there are examples and documentation in the LabVIEW Help. I suspect that if you do go with straight TDMS, you will probably save yourself further problems by not bundling your four inputs into a Dynamic Wire, but making them a 1D Array (or possibly a Cluster).
Bob Schor

Formatting the time stamp in "Write LabVIEW Measurement File"

When I use the "Write LabVIEW Measurement File" vi to write data
the files first column contains the number of seconds since the staart of the file
How can I get the computer date and time or at least the time HH:MMS???
Tom
PS, And how can I put some sensible label on each columns in the file?

Tom,
The vi I'm attaching demonstrates how to use the computer system time for the timestamp on your LVM file. It takes a reading from the DAQ Assistant and applies a system time stamp. It's in version 7.1, but let me know if you need it in version 7.0.
As for inserting meaningful column headers, you won't be able to do that with the express vi, but you could use the regular file i/o vis to create a file like that is similar to a LVM file, but is a little more customizeable and can be formatted however you like. The express vi is meant to be a quick solution, but does not offer all the versatility of the vis on the palette. I hope this helps you out. Have a good one, Tom!
Tyler S
Attachments:
LVM_timestamp_7_1[1].vi ‏265 KB

How to put the proper header at each column in write to measurement file (.lvm) ?

Hi,
i would like to know one thing about the write to measurement file. Can i put the proper header at each column in write to measurement file (.lvm) ? and how can i do for it ? Could you show me a way to make it ?
i am looking forward your kindly reply.
thank you so much ..
best regard,
roxy

Hi Mike,
Thank you very much for your help. It works .
By the way, i would like to ask you about setting time interval. In the pic, X_Value column is for time column
i would like to ask that when i use the write to measurement file, there got the x column that show time inside the excel file. In this column, i would like to set the time interval at every 210ms .The data may come in every msec but i just want to record the data at every 210ms . for example, 210ms-420ms-630ms ..etc. how can i set it ?
One more thing .. can i do it in graph as well ?
i am looking forward your kindly reply.
Thank you for your time.
Best Regard,
Roxy

Include time stamp in Write to Measurement file

Dear Experts,
I would like to include the time stamp in the data sheet I saved using a Write to Measurement file. Currently only 1 column of data was saved without the time stamp. Is there anyway I can save the data together with its time stamp in a single file (side by side column)?
Thank you.
Regards,
CYTeoh

Did you configure the Express VI to create a time channel:
Christian

Time with 'Write to measurement file'

Hello,
I am making an acquisition waveform. The integration time is 1s divided in 128 samples. When I execute the software, the datas are stored in a text file with 'Write to measurement file'. This text file is a continuous list of 128 numbers-packs in rows.
I want to add the time column (date+hour+minutes+secondes+1/10sec+1/100sec) in front of each number acquired. (And not only in front of the first number of the 128 package)
I have don t know how to add this.
Can you help me?
Thanks a lot.
(See file attached)
Attachments:
test3.vi ‏148 KB

Also, in the setup dialog for the Write Measurement File, there's an option to include an "X Column Value" that normally holds a timestamp.
Enable one of these options and any included timestamp in your waveform will go into this column. If you don't have a waveform, you can build an extra column in your array of data points with the needed timestamp and it will work the same.
Ed
Message Edited by Ed Dickens on 02-20-2007 03:37 PM
Ed Dickens - Certified LabVIEW Architect - DISTek Integration, Inc. - NI Certified Alliance Partner
Using the Abort button to stop your VI is like using a tree to stop your car. It works, but there may be consequences.
Attachments:
WLVMF Time Column.gif ‏9 KB

Hi am trying to save Data into a write to measurement file vi using a NI PXI 1042Q with a real time mode but it is not working but when i run it with uploading it into the PXI it save in to the file

Hi am trying to save Data into a write to measurement file vi using a NI PXI 1042Q and DAQ NI PXI-6229 with a real time mode but it is not working but when i run it without uploading it into the PXI it save in to the file please find attached my vi
Attachments:
PWMs.vi ‏130 KB

other problem is that the channel DAQmx only works at real time mode not on stand alone vi using Labview 8.2 and Real time 8.2

How to populate column titles for y values when using Write to Measurement File Express VI with a tab delimited text-based .lvm file?

The .lvm file generated by the Write to Measurement File Express VI includes column heading titles for the y values, but they are a default value of "untitled". See attached example of a sample file when opened in Excel, the values in question are highlighted. Is there a way to specify the column titles when the file is written?
This is a similar question to this posting, which received a work around response to use the Write to Spreadsheet File.vi, rather than a solution when using this VI.
Message Edited by Hightop Raven on 05-02-2007 03:37 PM
Attachments:
column_titles.gif ‏13 KB

Sorry for the late reply. I was out of the office Friday.
You can do it, but the code can get rather ugly. Under the hood, the dynamic data type (the dark blue wire) is an array of waveforms. In your case, the scalar values you convert to a dynamic data type are being converted to an array of waveforms, each waveform having one element. You have two options.
Explicitly convert your scalars to one-element waveforms (t0=0, dt=1) and add the title before conversion to a dynamic data type.
Convert your dynamic data type to an array of waveforms and loop through them to add the column labels. The conversion blocks are in the Signal Manipulation Express palette.
I would recommend 2, since it is the easiest to add. It is also the easiest to run only on the first iteration. Just put a case selector around the loop, wire the selection to the While loop iterator, and set the case containing the label code to 0. The default case simply passes through the dynamic data.
My apologies for not including a screen shot. I am in the process of upgrading my machine and can't run LabVIEW. If you need one, let me know and I can post one tomorrow.
This account is no longer active. Contact ShadesOfGray for current posts and information.

Help with saving time stamps to "write to measurement file" excel format.

I am having problems saving the timestamps from my data to the write to measurement express vi for excel. My incoming data is converted from dynamic data to a 1d array for processing, which I understand you lose the time stamp data. I added a new array for time stamps but this array then cannot be converted back to the dynamic data that is requested to go into the write to measurement file express vi. I would prefer to leave the data in an array to be saved rather than converting it to a waveform so is there any way to add the time stamps from my 1d array back into the write to measurement file?

I set it up to build a waveform now but I am still having issues with it saving the correct timestamp. The time just incriments for every second (as it did before converting the dynamic data to the waveform). I attached a screenshot.
Attachments:
waveform.png ‏36 KB

"Write to measurement file" in labview doesnt show time instants of the waveform

Hi
I am trying to write my data into a file. I am using the "write to measurement file" for this purpose. But, the file shows only the magnitudes of the input waveform and not the time instants.
Can someone help me with this.
Thanks
Vijay Chand Ganti

Hi
Thanks for ur reply. I tried using the "unbundle by name", but thats only helpful for a cluster of elements.What i need is to
get the time instants of an analog signal (to verify its sampling rate).
I am using the example under NI example finder-->Analog Input R series.
Mine is an FPGA application and so im using the R series. I am anyways attatching the VI which i modified for my use.
Attachments:
Analog Input (Host)2.vi ‏375 KB

Time format in 'Write To Measurement File' express vi

Hi,
I'm using the 'Write To Measurement File' express vi to save data acquired using a PCI-6221 board and the DAQmx vi s. The acquisition is continuous.
When I set the 'number of samples per channel' property of the DAQmx Read.vi to -1 (ie, read all available samples), the time is saved in relative format. When I set any other value (ie a certain quantity of samples), the time is saved in absolute format.
Do you know why the vi does this, and if there's any way of controlling the time format ?
Thanks,
ps : I use Labview 8.0

Hi Scalpas,
I look into what I believe you are doing , but I didn't see the same results. Can you explain what datatype you are transferring to the Write to Measurement file VI? Or provide a sample of code that demonstrates the issue.
I think it might have to do with the DataType conversions when writing that file.
Sappster

Write to measurement file at every n iterations

Hi guys,
I would like some help with saving data in labview 2010 SP1 (base development system). I am using a "Write to measurement fil express VI" inside a while loop and the data out from the DAQmn Read is wired to the signal in of the "Write to measurement fil express VI".
The way I have wired it is the VI saves the data as a text file after it has recorded 100 samples (the nuber of samples to read in this case was set to 100). I would like to know if there is a way to control the rate at which the express VI saves the data. As in, I want the express VI to save the data at specified time interval or at every nth iteration. I have attached the main VI and its 2 sub-VIs for reference. Please let know if anyone can help me resolve this issue. Thank you for your time and inputs in this regard.
Raj

Robert,
First, you must understand that the above code resides inside a loop. The blue square i terminal is known as the iteration terminal. It provides the current loop iteration count, starting from zero.
The first input (x) to the Quotient & Remainder Function comes from this iteration count (i) terminal of the loop.
The second input (y) to the Quotient & Remainder Function comes from the control N.
We wish to write to the measurement file every N iterations of the loop. If we take our current iteration count (i) and divide by our desired N, every Nth iteration of the loop, the remainder will be zero. For all other iterations, the remainder will be non-zero.
That being said, we check the remainder and compare it to zero. If it is zero, we will send a True value to the Enable terminal on the Write To Measurement File Express VI. Any time a True value is sent, we will write to file. Anytime a False value is sent, nothing will be written to the file.
The green new_file input on the Write To Measurement File Express VI is used when the "Save to series of files (multiple files)" radio button is selected in the Configure dialog box of this Express VI. When "Save to one file" is selected, this option does not apply, and so it is not included in the input list, which is why you are not seeing this.
This new_file input is used to tell the Write To Measurement File Express VI when to start writing to a new file.

Write to Measurement File time column wrong starting value

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