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

Similar Messages

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... 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]

"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 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

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 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!
Go to Solution.

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

Data read from text file(notepad) not enterd into particular field

Hi frends, I have used function "F4_FILENAME" and "GUI_UPLOAD" to upload a text file in notepad on my desktop to an internal table in SAP.after that i used the folowing code line to copy data from one table to other:
" insert tab2 from table itab accepting duplicate keys. "
But my problem is that in tab2 i have total 5 fields.In notepad file i have written following two words:
achal
mehra
now when i copy the data from itab to tab2 , it shows word "achal" in the field 1 of 1st row and "mehra" in field 1 of 2nd row only.
what i want is to store "a" in field1 "c" in field2 and so on in row 1.
similarly "m" in the second row and field1.
PLZ guide me.I am new to ABAP.

thnx frend but dear ur code has syntax error.Actually I am new to ABAP. I am using following code as a part of my program :
CALL FUNCTION 'GUI_UPLOAD'
EXPORTING
   FILENAME = d_file
   FILETYPE = 'ASC'
   HAS_FIELD_SEPARATOR = ''
   HEADER_LENGTH = 0
   READ_BY_LINE = 'X'
   DAT_MODE = ' '
     TABLES
     DATA_TAB = itab
     LOOP AT gt_file2 INTO lwa.
     EXCEPTIONS
       FILE_OPEN_ERROR = 1
       FILE_READ_ERROR = 2
       NO_BATCH = 3
       GUI_REFUSE_FILETRANSFER = 4
       INVALID_TYPE = 5
       NO_AUTHORITY = 6
       UNKNOWN_ERROR = 7
       BAD_DATA_FORMAT = 8
       HEADER_NOT_ALLOWED =9
       SEPARATOR_NOT_ALLOWED = 10
       HEADER_TOO_LONG = 11
       UNKNOWN_DP_ERROR = 12
       ACCESS_DENIED = 13
       DP_OUT_OF_MEMORY = 14
       DISK_FULL = 15
       DP_TIMEOUT = 16
       OTHERS = 17.
      IF SY-SUBRC <> 0.
                ENDIF.
      loop at itab.
        Write:/ ITAB.
        endloop.
insert zlfa4 from table itab .
plz guide me where i shud use ur code and plz write the exact syntax for me if u can.

Strategy and Process on how to best enqueue from the file system

I have a single database that must accept BFILES from one location via a directory folder, http text documents via proxy server, and unstructured XMLTYPE CLOB from another database.
I have created an ANYDATA queue, and will try to transform the dequeued output to XMLTYPE payloads for a pl/sql callback.
My problem is how to monitor both the file system BFILE folder, and the XMLTYPE CLOBS, to automatically begin then enqueue process. The queue would have to accept from (1) to anynumber of files, and given that requirement the use of an array batch is what I would like to use, but need to populate the array.
Any help would be most appreciated.
David

Thank you for the quick reply.
The database version is 10.2.0.3.
There are three sources of documents coming into the system.
Source 1: Outside entity (in-front of a secure firewall) who must place their XML (XSD compliant) files on a shared file system server (the BFILES).
Source 2: Internal entity (behind firewall) who publishes their XML files to a defined database directory on the database server.
Source 3: Enterprise Intranet contributors submitting their individual files via url.
On entry for each file they must be validated for XSD compliance then if passed submitted to the main enqueue for propagation to 5 additional process queues with separate callback procedures.
If reasonably possible, separate agents of some sort would "listen" at each folder location, then begin the enqueue process when either a batch of files or a single file is placed in the directory folder.
AQ itself has no such mechanism to monitor locations, and a scheduled job makes sense - however the job would have to continuously run given the very short processing requirement. However, using DBMS_SCHEDULER may be the best solution given ALL rhe requirements.
Thank you for your professionalism - I appreciate the assistance.

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.

Need help: Flex record webcam problem, how to setting Brightness,Contrast,Saturation and Sharpness

Hello, dear all
Please help me!
Flex record webcam problem, how to setting Brightness,Contrast,Saturation and Sharpness?
nsOutGoing=new NetStream(nc);
nsOutGoing.attachCamera(m_camera);
nsOutGoing.publish(filename, "record");
I want to control the Brightness,Contrast,Saturation and Sharpness for the recorded flv file.
At present, I only can control the videodisplay object, but I can not able to control Camera.
Thanks very much!!
kimi
MSN: [email protected]

Can I change a Video object to to Camera object, If yes, How do??
nsOutGoing.attachCamera(video as Camera);// it does not work rightly
thanks

How to read from excel file and write it using implicit jsp out object

our code is as below:Please give us proper solution.
we are reading from Excel file and writing in dynamicaly generated Excel file.it is writing but not as original excel sheet.we are using response.setContentType and response.setHeader for generating pop up for saveing the original file in to dynamically generated Excel file.
<%@ page contentType="application/vnd.ms-excel" %>
<%
     //String dLoadFile = (String)request.getParameter("jspname1");
     String dLoadFile = "c:/purge_trns_nav.xls" ;
     File f = new File(dLoadFile);
     //set the content type(can be excel/word/powerpoint etc..)
     response.setContentType ("application/msexcel");
     //get the file name
     String name = f.getName().substring(f.getName().lastIndexOf("/") + 1,f.getName().length());
     //set the header and also the Name by which user will be prompted to save
     response.setHeader ("Content-Disposition", "attachment;     filename="+name);
     //OPen an input stream to the file and post the file contents thru the
     //servlet output stream to the client m/c
          FileInputStream in = new FileInputStream(f);
          //ServletOutputStream outs = response.getOutputStream();
          int bit = 10;
          int i = 0;
          try {
                    while (bit >= 0) {
                    bit = in.read();
                    out.write(bit) ;
} catch (IOException ioe) { ioe.printStackTrace(System.out); }
          out.flush();
out.close();
in.close();
%>

If you want to copy files as fast as possible, without processing them (as the DOS "copy" or the Unix "cp" command), you can try the java.nio.channels package.
import java.nio.*;
import java.nio.channels.*;
import java.io.*;
import java.util.*;
import java.text.*;
class Kopy {
     * @param args [0] = source filename
     *        args [1] = destination filename
    public static void main(String[] args) throws Exception {
        if (args.length != 2) {
            System.err.println ("Syntax: java -cp . Kopy source destination");
            System.exit(1);
        File in = new File(args[0]);
        long fileLength = in.length();
        long t = System.currentTimeMillis();
        FileInputStream fis = new FileInputStream (in);
        FileOutputStream fos = new FileOutputStream (args[1]);
        FileChannel fci = fis.getChannel();
        FileChannel fco = fos.getChannel();
        fco.transferFrom(fci, 0, fileLength);
        fis.close();
        fos.close();
        t = System.currentTimeMillis() - t;
        NumberFormat nf = new DecimalFormat("#,##0.00");
        System.out.print (nf.format(fileLength/1024.0) + "kB copied");
        if (t > 0) {
            System.out.println (" in " + t + "ms: " + nf.format(fileLength / 1.024 / t) + " kB/s");
}

How to set up a basic file sharing server for my small architectural business?

I have no idea if I have posted in the correct area as this is my first forum post within the apple support community!
I have been using a 21.5" imac running 10.6.8 for the past 5 years to run my small home based architectural design business. I have been using the internal hard drive & backing up the necessary data to a simple usb external hard drive. I am now looking to firstly purchase a new imac 27" retina and purchase new autocad lt 2015 for mac software. I am looking to have another imac (my old mac) running in conjunction with the new mac. I want both macs to be able to access the same data and am slightly unsure what is the best way to achieve this.....As my old mac is currently only running snow leopard and an old version of autocad for mac 2011 it wont run on any more recent OS. Essentially i believe I have 2 main options with this.... (1) I Accept that I have to purchase 2 no. autocad lt 2015 licences @ a cost of £2300. Or option (2), I only run autocad on the new mac as this will be the primary station and the old mac used for primarily for admin & accounts. I have also recently discovered that it is possible to rent autocad licences for £300p/a which may also be another option (3)!
I previously had a problem where my hard drive failed on my mac & lost all data on the internal hard drive, luckily I had been backing up all data regularly to my external hard drive and now loss occurred! Obviously with any new system I want to ensure that my data is safe!
I currently utilise about 250GB of data for business operations but this will obviously grow with time.
In the future I would like to have the option of potentially being able to access the network data remotely via macbook pro whilst abroad although at this stage this really isnt my primary objective. Although I believe I could achieve this through apple remote desktop.
I suppose I should provide some information with regard to the required speed of the system...I regularly open 50-100 photos at the same time totalling around 250-500MB. I would like the system to be able to handle this fairly easily.
I have been trawling through forums and to be honest they are totally confusing me. I have also spent time on the phone to the apple business team and have also discussed my objectives with a member of the apple team in store.
There have been various options advised to me and I really do not know which is the most appropriate route forward.
1 - Using a mac mini as the file server and linking the 2 mac devices to this and backing up the mac mini to an external hard drive to ensure no loss of data.
2 - Using a time capsule as a file server and linking the 2 mac devices to this and backing up the TC to an external hard drive to ensure no loss of data.
3 - Using the new mac hard drive and linking the 2 macs via thunderbolt (old mac does not have thunderbolt and so I guess I would need another new mac?!) and then backing up the data to a time capsule.
4 - Using a RAID based server and linking the 2 no. macs.
Sorry to ramble but any advice really would be greatly received!

Hi sblemings,
Welcome to the community.
I think with your scenario you should ask yourself, how complicated do you want the setup to be and how much time would you have to be able to resolve an issue should one occur with this setup.
All the options that have been advised would work but they come with complexity and therefore time.
1 - Using a mac mini as the file server and linking the 2 mac devices to this and backing up the mac mini to an external hard drive to ensure no loss of data.
2 - Using a time capsule as a file server and linking the 2 mac devices to this and backing up the TC to an external hard drive to ensure no loss of data.
3 - Using the new mac hard drive and linking the 2 macs via thunderbolt (old mac does not have thunderbolt and so I guess I would need another new mac?!) and then backing up the data to a time capsule.
4 - Using a RAID based server and linking the 2 no. macs.
Sorry to ramble but any advice really would be greatly received!
option 1
Would be a way to achieve what you want, it would centralise your files and you would only need to backup your file server (as long as all the files you wanted backed up were on it). This could be achieved either using the client and sharing various folders or using Server which would give you more options than you would possibly need.
option 2
This is exactly like option 1 except that you wouldn't have to administer another mac however you may limit any future growth.
option 3
This option I probably wouldn't pick, you could achieve this with firewire and use a firewire to thunderbolt adapter (saves you having to buy a new iMac)
option 4
This option would, depending on your RAID level, give you disk redundancy but remember you would still need to back this up, as RAID is NOT a backup solution.
I would also ask is there a pressing need to keep the old iMac in service and complicating things by having a server / NAS? Could you not just transfer all your information over to this and continue with the one backup? I would say that doing it this was would be the simplest way of achieving what you want from what I can take from your question.
As for remotely accessing your data, if you have the right hardware the way to achieve this would be to use a VPN and connect back to your data. However a potentially easier way for you ,would be to use a service like logmein or teamviewer to connect back.
Hope this helps, and by all means any questions please ask.
Dan
How to set up a basic file sharing server for my small architectural business?

Problems reading from a file

Hey,
I have this file that I need to read so i can handle the contents. It was created in MSDOS and as I have very little experience in that topic, I wondered if anyone can point me in the right direction. I tried reading it as a ascii and binary file but neither work, I'm really just guessing though.
The file has no extension. Hence I can't upload it to the forum. Its made up of mostly meaningless strings of characters.
Any help is appreciated,
Regards,
Rkll

Rkll wrote:
Ya you're exactly right, its parsing the data that is the problem. I have done what you said and attached it as a .txt file. My inital thought was that it was a collection of binary digits but I was unable to read them with the built in Labview read binary file VI. Although maybe I had a setting wrong or something.
This has nothing to do with the Read From Binary File VI, or any setting. That functions does not magically know the format of a file, just like any binary file read for any other programming language. Thus, you have to tell it how to interpret the data. You can tell it to read the file as a series of bytes, and it will dutifully return to you an array of U8 integers. Or, you tell it to read it as a series of 16-bit integers and it will dutifully return to you an array of I16. It will give you what you tell it to give you.
Looking at the file I can see some header information, though it's not clear what all the spaces are being used for. I can't tell whether they're padding for a section, or what. As I noted, do you have any idea as to the format of the file? You said you're updating an old computer system. Any documentation?

"Read from Binary File" and efficiency

For the first time I have tried using Read from Binary File on sizable data files, and I'm seeing some real performance problems. To prevent possible data loss, I write data as I receive them from DAQ, 10 times per second. What I write is a 2-D array of double, 1000 data points x 2-4 channels. When reading in the file, I wish I could read it as a 3-D array, all at once. That doesn't seem supported, so I repeatedly do reads of 2-D array, and use a shift register with Build Array to assemble the 3-D array that I really need. But it's incredibly slow! It seems that I can only read a few hundred of these 2-D items per second.
It also occurred to me that the Build Array being used in a shift register to keep adding on to the array, could be a quadratic-time operation depending on how it is implemented. Continually and repeatedly allocating bigger and bigger chunks of memory, and copying the growing array at every step.
So I'm looking for suggestions on how to efficiently store, efficiently read, and efficiently reassemble my data into the 3-D array that I need. Perhaps I could simplify life if I had "write raw data" and "read raw data" operations that write and read only the numbers and no metadata.then I could write the file and read it back in any size chunks I please -- and read it with other programs besides. But I don't see them in the menus.
Suggestions?
Ken
Solved!
Go to Solution.

I quote the detailed help from Read from Binary File:
data type sets the type of data the function uses to read from
the binary file. The function interprets the data starting at the current file
position to be count instances of data type.
If the type is an array, string, or cluster containing an array or string, the
function assumes that each instance of that data type contains size information.
If an instance does not include size information, the function misinterprets the
data. If LabVIEW determines that the data does not match the type, it sets data
to the default for the specified type and returns an error.
So I see how I could write data without any array metadata by turning off "prepend array or string size information", but I don't see any way to read it back in such bare form. If I did, I'd have to tell it how long an array to read, and I don't see where to do that. If I could overcome this, I could indeed read in much larger chunks.
I'll try the auto-indexing tunnel anyway. I didn't tell you the whole truth, the 3-D array is actually further sliced up based on metadata that I carry, and ends up as a 4-D array of "runs". But I can do that after the fact instead of trying to do it with shift registers as I'm reading.
Thanks,
Ken

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

Similar Messages

Maybe you are looking for

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