"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

Similar Messages

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 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.
Unofficial Forum Rules and Guidelines - Hooovahh - LabVIEW Overlord
If 10 out of 10 experts in any field say something is bad, you should probably take their opinion seriously.

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

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.

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

Write to measurement file will not ask for file name once as selected.

When using the Write to Measurement file Express VI. I select "Ask user to choose file" and "Ask only once" with the intention that the data from each iteration simply be appended to the chosen file.
I select "Run continuous" and the VI asks for me to choose a file repeatedly anyway instead of just appending the first file. Selecting "Write to one file" properly appends data to the file specified in the box.
Am I doing something wrong?

DianeS wrote:
Personally I can't figure out why that particular button even exists (I'm told it's occasionally useful for debugging).
I find it useful if I am creating a subVI that is supposed to be a part of another VI. No while, loop just some inputs and outputs as a function. If I want to test it out stand alone and try a variety of inputs, then Run Continuous and change the inputs, then I see immediate feedback on the outputs. Once I'm satisfied its working right, then there is no need to clean up. Just save it and drop it in the large VI as a subVI.
Beyond that, I see no need for Run Continuous.

I want to write record type variable in ult file.How to i can write record type varable without column name.

I want to write record type variable in ult file.How to i can write record type varable without column name.
type rec_format_type is record
     format1 VARCHAR(3),
     format2 VARCHAR(3),
my_record     rec_format_type;
UTL_FILE.PUT_LINE(file_out, my_record);

ibney wrote:
I have below requirement.
DECLARE
     emp_data UTL_FILE.FILE_TYPE;
BEGIN
    emp_data := UTL_FILE.FOPEN ('EXDATAPUMP','TEST_BC_NN_PARALLEL.csv','W',32000);
    FOR TEST1 IN (SELECT /*+ PARALLEL(TEST_BC_NN,4) */ * FROM TEST_BC_NN) LOOP
        UTL_FILE.PUT_LINE (emp_data, TEST1);---Here i want to write record in utl file.without knowing the structure of table
    END LOOP;
    UTL_FILE.FCLOSE (emp_data);
END;
Why all the ugly upper case? You do realise that NO programming standard, ranging from Java and .Net, to C/C++ and Ada (of which PL/SQL is an implementation of), use upper-case-for-reserved-words as a standard.
The easiest and simplest way to address your requirement is as follows:
SQL> create or replace type TStringArray is table of varchar2(4000);
2 /
Type created.
SQL>
SQL>
SQL> begin
2          for c in(
3                  select
4                          TStringArray(
5                                  to_char(empno,'000000'),
6                                  ename,
7                                  to_char(hiredate,'yyyy-mm-dd')
8                          ) as COLS
9                  from    emp
10                  order by empno
11          ) loop
12                  for i in 1..c.Cols.Count loop
13                          dbms_output.put( c.Cols(i) );   -- write column
14                          if i < c.Cols.Count then
15                                  dbms_output.put( '|' ); -- write column separator
16                          end if;
17                  end loop;
18                  dbms_output.put_line( ' *end*' );               -- write record terminator
19          end loop;
20 end;
21 /
007369|SMITH|1980-12-17 *end*
007499|ALLEN|1981-02-20 *end*
007521|WARD|1981-02-22 *end*
007566|JONES|1981-04-02 *end*
007654|MARTIN|1981-09-28 *end*
007698|BLAKE|1981-05-01 *end*
007782|CLARK|1981-06-09 *end*
007788|SCOTT|1987-04-19 *end*
007839|KING|1981-11-17 *end*
007844|TURNER|1981-09-08 *end*
007876|ADAMS|1987-05-23 *end*
007900|JAMES|1981-12-03 *end*
007902|FORD|1981-12-03 *end*
007934|MILLER|1982-01-23 *end*
PL/SQL procedure successfully completed.
SQL>

Write to Measurement File Express VI: file name prompt

I am using the Write to Measurement File express VI to write some data.
Even though I have not selected "ask user to choose file" and have set a default filename, the vi still prompts me to choose a file. I tried restarting my pc and it used the default filename the first time and then went back to prompting me. I have set the default to overwrite my existing file each time, so I don't understand why I keep being prompted. If you look in the express VI the "ask only once" radio button is selected and greyed out, but I don't know why; I didn't select it.
(I have the express VI in a while loop and want it to write a line of data to the file each time the loop executes, so it's not convenient to be prompted for the filename each time)
I'm sure this is my own silly fault but would appreciate some advice
Thanks, klara
Attachments:
2PDCal_USB1v3.01.vi ‏441 KB

I'd suggest changing the mechanical action of your stop button from "Switch When Pressed" to "Latch When Released". This might be the only problem. If you didn't manually change your stop button back to false before running again, your loop would run once and stop, and you'd immediately see the file dialog from the Format Into File function. Changing the mechanical action would prevent you from needing to manually change it back to false before the next run.
Message Edited by Jeff B on 02-07-2008 08:48 AM

How to change 'untitled' in 'write to measurement file' block

Hello, when i use the write to measurement file function I can open up the data file as a txt. The data is shown in columns just like i want, but i want to change the column titles from Untitled1, Untitled2 etc... to something else. I dont see how to do this.
Thanks
- Dan

Here is the only way I can figure, and this is using the Set Dynamic Data Attributes express vi. Basically, I have 5 channels setup under a task in MAX, and since I'm not using the DAQ Assistant express vi (which, btw, can't access an existing task, as it only selects channels to create a new task), my tasknames don't get bundled in that nice little "Dynamic Data" wire. Hence the Untitled column headers in what is written, and unnamed signals anywhere else its used. Its a shame that we have such a convenient way to write a measurement file, but DAQread.vi is unable to output dynamic data.
This is the only way I could think of to make it work; It's real simple, but looks real messy in the midst of my rat's nest of wires and vi's. For every single channel you want to name, it seems you will need a separate instance of this Set Dynamic Data Attributes.
Attachments:
Signal Attributes.JPG ‏38 KB

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.

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

Write to measurement file timing

I am trying to make a VI that allows the user to turn on and name channels through the front panel. After the user has configured the channels, they can push a button and record voltages from the enabled channels and save them using the "Write to Measurement File".vi. I would like the user to be able to record a measurement file that is consistent in length each time they push the button...in this case, 5 seconds of data. The current VI doesn't appear to be doing this...everytime I push the record button, the data gets recorded for 0.045 seconds. Apparently I must be missing something as this isn't behaving how I expected it to. See attached VI.
Attachments:
Select Channel rev 3.vi ‏244 KB

It waits 5 seconds then saves the last 10 samples. Because that is the way you programmed it. The while loop returns only the data from the last iteration.
Two ways to do what you want: 1. Read 5 seconds * 200 samples/second = 1000 samples. No loop required.
2. Read 10 samples at a time and accumulate the data until you have 5 seconds of data. To avoid memory reallocations the way to do this is to Initialize an array with 1000 elements outside the loop. Wire it to a shift register. Inside the loop Read the samples and use Replace Array Subset to put the new data into the initialized array. Wire the output of the shift register to the file VI.
You generally should not put any time consuming code inside an event structure. Read the caveats in the detailed help for the event structure. Consider a Producer/Consumer architecture.
Lynn

Quickie: Write to measurement file VI, how to create new file?

I am using the write to measurement file express VI in my code and I have wired into it a control that sets the location to save the measurement file
The only problem is the measurement file has to exist first!! I cant for example, from the front panel, click the browse directory box, navigate to a folder and type in a name for the file. It just says file not found! Its like the file directory control is opening a file to save to, rather than creating a new file in that location
How can I solve this?
Solved!
Go to Solution.

Project attached
If I go in browse options what do i do? Just chose new and existing files?
Attachments:
engine.zip ‏119 KB

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

"write to measurement file" specify column names

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