Datalog as a buffer file

Similar Questions

• Reading, writing datalog file only once

  Can someone tell me why I can only read/write to a file once datalog.  Once the file created, read and written to it will not work the second time.  I tried to adjust the position without success even if the default position is at the beginning of the file and the first record.

  Thank you

  Matt

  Try this one.

• Memory is full (~ 10 GB datalog file)

  Hello

  I developed an application that generates a temporary file (*.csv) record datalog with @10ms. after a trial of ~ 3 days, I need to merge all the temporary files into a single file.

  implementation: to merge into a single file, I calculate the total line is every temp. File and reading k 25 ranks by iteration, and I write in the file main datalog. When the file size reaches ~ 400MB. I have labview: memory is full error. in the loop, I used "deallocation request" palette ", but did not work."

  I enclose the screenshot of the code. Please suggest me a solution

  
  

• Can I save a file datalog in LV format 7.1 of a program written in BT 8.2?

  I have a program I wrote there in LabVIEW 7.1 years.  He used inspection data in a file datalog.  I do a new programming in LabVIEW 8.2 who needs to write files of control that can be used by software version 7.1.  I do not have access to change the old software.  Is it possible for me to write files datalog in format 7.1 using the new program from 8.2?  I looked everywhere for an answer to this problem.  Please let me know if you have a solution!

  Last update: I solved my problem by doing the above.  I write a text file in the temp directory and then call the program written in LV 7.1 to write the datalog to the data file in the temp directory.

  BTW, I learned my lesson; No files datalog more!

• How can I recover datalog records written beyond the 2 GB limit?

  
  

  I found a solution.

  Here are the steps I took to divide a datalog large (> 2 GB) file into two files more small datalog (each< 2="" gb)="" so="" that="" all="" records="" could="" once="" again="" be="" accessed="" by="" an="" application="" that="" employs="" datalog="" file="">

  1. Open the file datalog as a byte stream file using file open/create/replace.
  
  
  2. Search the file for a sequence of bytes corresponding to the ID of the record to the first record to retrieve using binary file reading. (I knew my type of cluster datalog this ID U32 Record marked the beginning of a record.  For efficiency reasons, I have read 100 000 bytes blocks every time and kept track of the byte offset location in the file.)
  
  
  3. Search the file for a sequence of bytes corresponding to the ID of the next record (or eof if it was the last record) to determine the size of the current record.
  
  
  4. Read the current record in a byte array using read binary file in conjunction with the Position of defined file that works correctly for files up to 4 GB in size.
  
  
  5. Repeated steps 2 through 4 for the other subset of records targeted for one of the new files datalog.
  
  
  6. For each byte array, flattened the array of bytes to a string (precede the size of the array = False) and then not flattened the binary string (data includes the size of the table = False) according to my record datalog type.
  
  
  7. Save each record not flattened (cluster) to the new file datalog.

  Using the above procedure, I was able to bypass the need to create my own datalog file headers so I did not need to understand the specifications of datalog file format.

• Smart way to save large amounts of data using the circular buffer

  Hello everyone,

  I am currently enter LabView that I develop a measurement of five-channel system. Each "channel" will provide up to two digital inputs, up to three analog inputs of CSR (sampling frequency will be around 4 k to 10 k each channel) and up to five analog inputs for thermocouple (sampling frequency will be lower than 100 s/s). According to the determined user events (such as sudden speed fall) the system should save a file of PDM that contains one row for each data channel, store values n seconds before the impact that happened and with a specified user (for example 10 seconds before the fall of rotation speed, then with a length of 10 minutes).

  My question is how to manage these rather huge amounts of data in an intelligent way and how to get the case of error on the hard disk without loss of samples and dumping of huge amounts of data on the disc when recording the signals when there is no impact. I thought about the following:

  -use a single producer to only acquire the constant and high speed data and write data in the queues

  -use consumers loop to process packets of signals when they become available and to identify impacts and save data on impact is triggered

  -use the third loop with the structure of the event to give the possibility to control the VI without having to interrogate the front panel controls each time

  -use some kind of memory circular buffer in the loop of consumer to store a certain number of data that can be written to the hard disk.

  I hope this is the right way to do it so far.

  Now, I thought about three ways to design the circular data buffer:

  -l' use of RAM as a buffer (files or waiting tables with a limited number of registrations), what is written on disk in one step when you are finished while the rest of the program and DAQ should always be active

  -broadcast directly to hard disk using the advanced features of PDM, and re-setting the Position to write of PDM markers go back to the first entry when a specific amount of data entry was written.

  -disseminate all data on hard drive using PDM streaming, file sharing at a certain time and deleting files TDMS containing no abnormalities later when running directly.

  Regarding the first possibility, I fear that there will be problems with a Crescent quickly the tables/queues, and especially when it comes to backup data from RAM to disk, my program would be stuck for once writes data only on the disk and thus losing the samples in the DAQ loop which I want to continue without interruption.

  Regarding the latter, I meet lot with PDM, data gets easily damaged and I certainly don't know if the PDM Set write next Position is adapted to my needs (I need to adjust the positions for (3analog + 2ctr + 5thermo) * 5channels = line of 50 data more timestamp in the worst case!). I'm afraid also the hard drive won't be able to write fast enough to stream all the data at the same time in the worst case... ?

  Regarding the third option, I fear that classify PDM and open a new TDMS file to continue recording will be fast enough to not lose data packets.

  What are your thoughts here? Is there anyone who has already dealt with similar tasks? Does anyone know some raw criteria on the amount of data may be tempted to spread at an average speed of disk at the same time?

  Thank you very much

  OK, I'm reaching back four years when I've implemented this system, so patient with me.

  We will look at has a trigger and wanting to capture samples before the trigger N and M samples after the outbreak.  The scheme is somewhat complicated, because the goal is not to "Miss" samples.  We came up with this several years ago and it seems to work - there may be an easier way to do it, but never mind.

  We have created two queues - one samples of "Pre-event" line of fixed length N and a queue for event of unlimited size.  We use a design of producer/consumer, with State Machines running each loop.  Without worrying about naming the States, let me describe how each of the works.

  The producer begins in its state of "Pre Trigger", using Lossy Enqueue to place data in the prior event queue.  If the trigger does not occur during this State, we're staying for the following example.  There are a few details I am forget how do ensure us that the prior event queue is full, but skip that for now.  At some point, relaxation tilt us the State. p - event.  Here we queue in the queue for event, count the number of items we enqueue.  When we get to M, we switch of States in the State of pre-event.

  On the consumer side we start in one State 'pending', where we just ignore the two queues.  At some point, the trigger occurs, and we pass the consumer as a pre-event.  It is responsible for the queue (and dealing with) N elements in the queue of pre-event, then manipulate the M the following in the event queue for.  [Hmm - I don't remember how we knew what had finished the event queue for - we count m, or did you we wait until the queue was empty and the producer was again in the State of pre-event?].

  There are a few 'holes' in this simple explanation, that which some, I think we filled.  For example, what happens when the triggers are too close together?  A way to handle this is to not allow a relaxation to be processed as long as the prior event queue is full.

  Bob Schor

• InputStream/transfer/file upload file size limitation?

  I try to use http 'POST' to download a large file whose size is about 30 MB.

  I cut it in small pice like 1 Mb. And try to send them on httpconnection.

  Both Simulator and real phone do not work, I got OutOfMemory error.

  Also I tried to use the browser to download, still does not.

  Y at - it no limitation of size for file transfer via http?

  Thank you.

  LAN

  Moreover, myFileStream.read use InputStream.read method.

  myHttp.open(theServer);        myHttp.setRequestMethod("POST");        myHttp.setRequestProperty("Content-Type","multipart/form-data; boundary=" + BOUNDARYKEY);        myHttp.openOutputStream();
  
          myHttp.write(getPostFormHeader());        if (myFileStream != null){            int fileSize = (int) myFileStream.fileSize();            if (fileSize <= 0)                System.out.println("Invalid file size!");
  
              int off = 0;            int len = 0;            int i;            byte[] myBuf = new byte[BUF_SIZE];            for (i=0; ; i++) {                if ( (fileSize - off) < BUF_SIZE)                     len = fileSize - off;                else                     len = BUF_SIZE;                if (len <= 0)                    break;                myFileStream.read(myBuf, 0, len);                myHttp.write(myBuf);                off += len;            }            }        myHttp.write(ENDMESSAGE.getBytes());        myHttp.flush();        return myHttp.getResponseStream();
  

  Hi dream,

  For a load of 30 MB to succeed the phone, he'll need 30 MB successfully create the PUBLICATION on the server information, it is then the main cause of the "OutOfMemory" error, the problem behind this error is that the "Ras" on Http/sConnection command deletes not really the send buffer file Info. So independently using pieces of 1 KB or 1 MB buffer memory is still going to fill and eventually cause an OutOfMemory exception. One of the two way around this is to split the file into smaller files; Send to each of them through his OWN POST and then rebuild Server; A nice way to fix this is to divide the file in archive zip/rar/segments and then simply "extract" the new server-side.

  If you are interested by this unfortunately and costly route, you can find the article relevant here this article refers to the download instead of download, but the same logic applies.

  The second option is to use a datagram Socket connection / (rinse them properly) and get them to do the HTTP traffic for you.

  Concerning

• Flash videos (youtube and vimeo, incorporate or not) do not play even if the controls indicate that playback is in progress.

  As YouTube and Vimeo 41.0 videos do not play even if the video controls show that reading is current. True to embed, Facebook and YouTube pages. On Youtube, video will buffer to 100% but will not play again. First frame of the video is visible at a time, but remains a fixed image. FlashBlock is installed but disabled.

  On YouTube, if you click on the pause button, and then click the play button, the video then play? (I have not checked on Vimeo yet.)

  If so, you can have the autoplay disabled HTML5 videos. From 41 of Firefox, it's more effective than in previous versions because reading is blocked, but there is the strange display of the pause key and the buffer file.

  To check this setting:

  (1) in a new tab, type or paste Subject: config in the address bar and press enter/return. Click on the button promising to be careful.

  (2) in the search above the list box, type or paste the media and make a pause so that the list is filtered

  (3) if the preference media.autoplay.enabled is in bold and 'game of the user' to false, you can double-click it to restore the default value true and see if that fixes it

• WALKMAN MP3

  My Mp3 has suddenly stopped working. It will not turn on, or help the reset button. I troubleshoot and it allows the "browse files" on however, it deleted my music storage, and I can't add music to it, nor implemented a buffer file. How to format this device on the computer and or implement the storage of music in my MP3 again?

  [Moved from comments]

  Contact Sony for assistance with their product.

• QFile created vs lastModified

  I would get the two stamps of QFile:

  created()

  lastModified()

  It seems that the BB10 always replace created()

  file is stored in my sandbox/data

  I test if the file exists, and then I do something like this:

  QFile file(myPathToFile);
  if (!file.open(QIODevice::ReadWrite)) {
      return;
  }
  .....
  file.write(*buffer);
  file.flush();
  file.close();
  

  now created() changed

  Because I'm replacing the contents of an existing file, I expected to have unchanged created() and lastModified() updated.

  or I'm doing something wrong update the content of a QFile?

  PBernhardt wrote:

  According to the docs, "if creation time or time of"last status change"are not available, returns identical lastModified().

  https://developer.BlackBerry.com/native/reference/Cascades/QFileInfo.HTML#created

  Looks like that's not available. Might be worth a feature in this case request.

  so I'll create a feature request

  I read the docs, but could not imagine that a modern OS like BB10 does not provide something basic like a timestamp of creation of file ;-)

• Error FRM-41839

  Hi all
  I start to receive "FRM-41839: disk i/o on the disk error temporary buffer file /tmp/filebfKMCw.TMP.
  When I hit OK, I get "ORA-01403 no data found ' and ' FRM-40507: Oracle error: cannot get next request record.»
  
  He's filebfKMCw.TMP $
  -rw - r - r - 1 applprd s/n 536177 Jul 21 14:01 filebfKMCw.TMP
  
  Is it a space in the directory/tmp?
  
  Thank you
  Eugene

  Hello

  See (Note: sendmail 737897.1 - how to remove Messages from queue) for steps clean this directory, or just add more space (move the directory some other partitions with enough space).

  Kind regards
  Hussein

• Card data scope of device to the TDMS file buffer

  How transfer brought data card device buffer to TDMS file directly bye passing buffers LabVIEW and Windows. In the same way as DAQmx configure logging (VI) do we have any function scope?

  The API OR-SCOPE doesn't have the ability to record data acquired directly on the disc like the DAQmx API offers.  All data must be retrieved from the on-board memory, which makes data transfer OR-SCOPE kernel driver via DMA, and a copy must then happen to transfer data from the space of the kernel in user space (LabVIEW), how it can be manipulated.

  The main reason for this flow is because the calibration scale occurs in the NOR-SCOPE driver and not the material.  So if you were to save data directly to the disk as DAQmx, he stock raw ADC codes, without correction calibrated.  The API OR-SCOPE allows to recover the coefficients of scale if you want to apply them at a later date after extraction of the data from the hardware.  To optimize flow of data applications, it is recommended.

  The only exception to the logging directly on the disk would be the Oscilloscope Reconfigurable SMU-5171R.  It is being implemented with LabVIEW FPGA firmware using the design of Instrument libraries, code is open for editing.  With the open nature of this software stack, it is possible to implement "direct to TDMS" functionality with LabVIEW FPGA Read region node.

  I hope this helps!

  -Nathan

• File dialog box works no more Support files Datalog

  How can I get rid of the file dialog function no Support Datalog Files any longer? »

  UH... could you repeat your question please? With a little better explanation? As it is, I don't know if you're wondering if it supports it, or if you complain that it does not, that I do not understand, since the file dialog box is just for file selection. Are you aware of the Datalog functions?

• Adding in a Datalog file

  I'm unable to add data to the datalog file in the attached example.  It saves the data to the first save iteration but won't add data on subsequent iterations save.  In exmple atteched save iteration is 5 seconds.  In the effective application of the iteration save will be hourly because a few days worth data necessary to be connected at a rate of 50 MS.

  Please indicate how I can get it to add data and how the example can be improved.

  I'm using Win - XP and LV 8.6.

  Thank you

  Dave

  Hi dj,

  you are writing in the file of datalog - it grows with time...

  The problem is: you read only the first datablock!

  You write the revenge of 100 lines and if you read the revenge of 100 lines.

  While you always open the file again you always read the first datablock... And the number of reading is unwired, so by default! comes into play!

  I suggest you:

  -Use a queue to move data between the loops.

  -Use a different dataformat such as simple binary files. What happens when you allow 25 rows of data, but want to read 100 lines of data? (Which is what happens when reading and writing data type will be different?)

• Can LabWindows libraries call function inherited from read the Datalog file?

  We are currently updating some old software written in LabVIEW 6.0.3 to Java. One of the features of the original software is to create data files using the function "Write Datalog" and also remind these databases later using 'Read Datalog'.  To maintain backward compatibility with old data users, we want that new software to also be able to read and display the old datalogs.  I have read several posts here about how the only way to get data off datalogs uses the function 'Reading Datalog' of the same version of LabVIEW to write the paper in the first place. I have the original LabVIEW code so I don't know the structure of the data that has been written.

  I want to know if there is the same function in LabWindows libraries.  Specifically is there is no support for a 6.0.3% version of the function of reading Datalog to support interfacing with a call to java?

  To knock out a possible solution, this software is shared with clients.  We want to avoid the way of compiling an executable separated from LabVIEW to be distributed with the main Java software which batch processes all the old data files in reading them with the old function of LabVIEW and spitting out files in a new format.  We would prefer for the old files to be transparent open into the new software.

  WARNING: I use LabVIEW for dark days before the invention of the button cancel, but never touched LabWindows/CVI. Please enter slowly so I will understand

  Thank you all!

  I guess that is not a built-in library capable of reading files datalog LabVIEW simply because they do not have a fixed format... Even in LV, you will need to pass the data structure for the opening function in order to be able to read the data back.

  Searching the forum I found this discussion that can give you useful to begin with.

  Apparently, you need detect the beginning of the section of the data file after the initials "DTLG" and rest of the header (which is the part not documented). After this point, read the file should be simple if you know the data structure the program writer used. The data > storage section of LabVIEW help can give you information about the content of the memory of each type of data used.

  A simple test, I did write the clusters with a string and an integer shows that: 1. section of data begins at offset 0x22F; 2. the cluster is poured into the file preceded an int with the length of the string; 3. documents may have a variable length according to the length of the string; 4. There are no bytes of padding between elements of the cluster; 5. records are packed in the file consecutively.

  I did this test using LabVIEW2009: it is possible that older files of LV are structured differently.

  An alternative to this is to generate a DLL in LabVIEW that reads files datalog and passes their content to the appellant. Since you are experienced in LV, you are certainly more comfortable than me by doing this.