Read a piece of waveform data

Similar Questions

• How to extract a D 1 waveform data in different channels to use for calculations on a page of data in real time

  Hi all

  I am a fairly new user to Labview and am trying to create a program that: watching the entries in different modules (9213, 9217) CompactDAQ sensors check errors and then uses data from some final calculations like averaging etc.  I've set up a small piece of code that includes the main functions that I am trying to accomplish.  Now I'm rather uncomfortable with getting set up and assigned channels, then pass these data in a while loop that continuously pulls the data from these sensors.

  I have the vi calculations complete and complement the inputs of channel UI, now, I'm working on the side of data manipulation and reading things.  The waveform D 1 who comes to read function is currently divided into components I want (given String Name and Y).  He then transmit this information out of the loop via a queue which transmits to the parallel loop below that will perform the verification errors and calculations of average.  There are some things that make it difficult. I showed the 2 sensors in my example, but in the actual program, there may be up to 400 entries.  The problem is that not all of these sensors will be used on all the tests that the software is used for.  To use the entries in the VI test for example: if I'm trying to the average of these 2 entries to create a common value, but then on a test, sensor 2 is not there, it must be recognized that fact and not use it in the service average.

  So to get down to it, I want to create something that can look through the D 1 waveform data groups, determine what these values are, then perform the functions necessary for these numbers once they are identified, then pass on the calculations of VI where it displays then usable for user information.  I think I'm having a problem with the finding in sorting than what I thought at makes me think that there must be an easier way.

  If someone has encountered this?  What is my explanation of what I'm trying to make sense?  Let me know and I can clarify.

  In terms of features, I don't see anything wrong. with respect to the effectiveness we must remember some general indications. These issues that I bring to the top will not affect your code now since your stack sizes are very small but can start to create the fragmentation of memory and slow down the software if your stack sizes are much larger and the software runs for a long period of time.

  1. try not to use the table to build. Whenever you use a table built labview creates a copy in memory. Try to initilized your berries and replace subsets.

  2. as much as you can try not index tables or unbundle cluster several times. try to perform as many tasks as possbile in one shot. (what was obvious in your second loop)

  In addition, he's looking good.

  I made a few changes to your code and attached to it. I wanted to give you a different on her opinion as it relates to being able to control entry and exit of programitically, if you had a look up table. I do not have the same changes to your second loop but I can guide you through what to do if you do not want to go in that direction. Yet once your original code is well done for someone who is new to labview, so don't feel you need to follow the new design of VI. Just try to remove the table construction and multiple indexing as a good habbit programming.

• Process of waveform data (accumulated results)

  Hi all

  I am currently treating a waveform data that I read of DAQ card. Data are digital waveforms, so first I convert it to table DBL and then put the table in a block of prcessing (see attachment). Since I expect to get a report and indeed I got what I want at the first time. However, when I re - run the program, obtained results. for example the first time I got 0.5, then when I re - run the program, I expect to get another 0.5, however what I have is 1. If I keep running again, he continue to accumulate.

  Can someone tell me what's wrong with my program? I have attached a screenshot of the code and also the vi that I used to do the processing.

  Thanks in advance for your help.

  Main program:

  

  You have an uninitialized enter your last registry FOR loop to shift.  Initialize to 0 and you should be good to go.

  

• Question on waveform data

  What is the difference between waveform data and common digital data? Whenever I have do analog data acquisition, the Board always wonder if I want to put the data acquired as a waveform or DBL type. For a specific data source, there is large difference for the two choices? If I chose to acquire waveform data, how to set the sampling frequency? I mean what I will get in a "waveform sample? Will it be a number or a set of numbers that contributes to a "wave"?

  Thank you!

  Right. A waveform data type can also have attributes assigned as the channel name. Read the help for a complete description.

• Access waveform data passed in a DLL

  Hello

  I'm working on a LabVIEW application that processes the continuous stream, 2 ms/s, 32 analog input channels, each channel. This application has a DLL built in order to improve the table great handling performance in LabVIEW. Initially, I fed the DLL with a double 2D array returned by DAQmx Read VI and worked on a controller embedded high performance. However, the new requirement is, I need to treat timestamps as well as each Read call to HAVE him, and that's why I need to feed the DLL with the waveform data returned by DAQmx Read. Output waveform contains the timestamps I need.

  The problem is, I don't see an easy way to access the data of waveform within the DLL (developed using Visual Studio C++). The type of waveform data seems to be a C++ class, and who looks like I need to add a considerable amount of code to retrieve the data within the class of waveform.

  My question is, LabVIEW naturally does support access to waveform data in a DLL and if there are examples of code? I understand, I can you can also process outside the DLL waveform data and feed the DLL with the array element in the waveform data. However, I have concerns about whether if performance will be significantly affected.

  Thank you!

  Donghui Yin

  Doy says:

  Sorry for the incomplete design details. If you are interested, I have used high cards, not PXI. This is why I don't have a problem of bandwidth PXI. Special assistance, I need right now is the note, 'External Code in LabVIEW using' manual on Page 2-7:

  "Note waveforms, digital signals and digital tables can be passed through shared
  "libraries, but access to the data inside shared libraries is not supported at this time."

  Thank you.

  I think that the text is clear enough! There is no documented API for access to international it data waveform within an external code module. The generated data type the node in library call for such a parameter is HWAVE or something, indicating that it is an opaque handle whose implementation details are deprived of LabVIEW. Since there is no documented API for access to her international of such data there is simply no way to access it.

  And I didn't know all the functions that are exported in the LabVIEW executable that I could easily connect with the waveform dataype. Even if I had, we still do not know the prototype (aka list of parameters and types) of these functions.

  Your only viable solution is to work with the data types supported. Your C code, or possibly the LabVIEW (table handles) native data type, either passing data in table C. else pointer would require reverse engineering of disassembly, a legally questionable approach, but also a lot of your time. And everything you would find this way I would be very hesitant to use in what feels, walks or crawls like a real-world application, since you can't be sure that your conclusions will work for any situation. It is also likely that your results will depend on some attributes may change between versions of LabVIEW.

• determination of the sampling rate and the frequency waveform data record

  Hello

  I write a simple program that collect data from a triaxial accelerometer input, convert it to a frequency spectrum, and then save the time domain and the frequency of the waveforms in an external file separated.  I don't understand how to set the sampling frequency, however.  On the DAQ Assistant, I updated the acquisition mode "Samples continues" and read samples is 2 k, which corresponds to the total number of data points that are collected.  How can I program sampling for awhile, it 30 seconds, for example?  Wouldn't be better to set up a trigger, as it will continue to collect data up to what I told it to stop?

  I also want to save waveform data in a separate file that can be easily seen by other computers that have not installed Labview.  I have currently the program put in place to convert a text string of the waveform of the time domain and then save it in a text file or a spreadsheet.  It works fine, but I would also like to record the frequency wave, which is a different type of data.  How can I do this or is there a better way?

  My program is attached.  Thanks for your help!

  Here's how you can use the shift register to build the table, and also where you can choose to play exactly 100 samples per while the loop iteration.

  

  Brian

• problem with the history of EEG waveform data

  Hello world:

  I use SIT to create a user interface in Labview to communicate with a simulink model. After I configure the SIT connection manager and run the vi, the output was displayed in waveform graph.

  Now, I want to get all the data in the history of the map of waveform. I tried to use the graphic story property node to access the whole of the historydat. But nothing copied in the part of Y in the front of the cluster of waveform...

  Can someone give me a helping hand on what is the problem? or has anyone encounter the same problem when you use SIT.  I am really confussed...

  I've attached the vi, but to run the vi, you must have a simulink model corressponding and SIT, so I'm really sorry that you can not run it

  And thanks a lot a lot a lot for that.

  / Shangning

  I just realized this data is a 2D waveform table, which contains the waveform 2000 * 1, and each waveform data contains only 1 value of Y.

• get the timestamp of waveform data

  Hi all

  I'm coming out of the timestamp from waveform data if this is possible. I am writing to file, but the express vi does not allow for fractions of a second and when I write a string waveform data for use with writing to the worksheet, the data of time is lost.

  any suggestions?

  Use Get waveform components. What part of VI? Writing to a file of measure written fractions of a second.

• Filter for waveform data

  Hello world

  I'm trying to filter the noisy analog inputs of 10 channels (DC). I'm sampling of 100 samples/channel at 1000 Hz. My idea is to filter the data with a low pass filter (cut to 10 Hz 3rd order butterworth low freq) and then to calculate the average of each package of 100 samples. Finally, I would like to receive values at a rate of 10 Hz, which can be displayed on the front panel and be written in a file of measures.

  My problem is the following:

  The Express filter VI does not filter continuously after that the VI began. It seems to reset each time the loop runs. The table of 100 samples (white) before and after (red), the filter appear in the image "filterResponse". If I take the average of this table, it is of course less without the filter due to the transitory values between 0 and 0.025 s. I built a simplified version of my VI with only one channel using the VI "Simulate signal" and my concept seems to work well which is permanently (see "filterMeanExample.vi"). I get the idea that it might have to with the kind of dynamic data that is supported by many express VI. But since I'm on the VI KEITHLEY, I do not use the type of dynamic data. In fact, I had to convert a waveform data type to get a vehicle appropriate for the file of the measurement of its release.

  I wonder how to keep the filter VI of reset each time that the loop runs.

  My VI is rather large and contains the KEITHLEY 'Acquire signals' VI which most people do not have in their libraries, so I decided to show only the images.

  Thanks for your help!

  Phil

  System: WinXP, LabVIEW 8.2.1 Professional

  Thanks for the tips, I am set!

  I used the VI of butterworth filter in the tool box to filter on the Panel of the Signal processing that accepts the type of table data. I put the variable ' init/cont' true to prevent the filter to reset its initial States to 0. I guess, it was my real problem before. The Express filter VI doesn't have this option, so I wasn't aware of this feature.

  However, an image of the current value is attached.

  Thanks again,

  Phil

• Detection of peaks of waveform data

  Hi people.

  It is probably obvious, but I can't understand it. In the attached VI sine wave detector summits are determined from a simulated signal. I want to be able to do the same thing with a waveform data (DBL), but it won't let me. How can I extract the signal of the LDM to feed the rest and make the waveform work VI right Ridge detector?

  Thank you

  Select this option.

  Use of DDT, found in the range of Signal handling, to change the dynamic thread in a waveform.

  Bob Schor

• How to read the two columns of data from the Port series

  Hello

  I'm reading two columns of data from the serial port.

  Example:

  52439 52430

  52440 52437

  52209 52214

  51065 51070

  52206 52390

  I use the serial of Visa service and I can read the first column of data from the serial port, but I can't understand how to read the second column.

  I want to both sets of chart data.

  I enclose my VI.

  Thank you for your help.

  The analysis of string function takes a "Format string" on top (with the right button of the function and choose Help, which explains all the entries).  In particular, you can say 'Give me two numbers separated by a tab' and the output will be two numbers (whole or floating, depending on the chosen format).  In particular, %d\t%d specifies a decimal integer, , whole decimal.

• Writing of continuous waveform data

  Hey,.

  I can't change the continues writing data to the worksheet found code here.  I modified the code to write data to a spreadsheet so I can get a timestamp to the data that I collect.

  My problem is this: whenever I run the code it rewrites the header of waveform information in the spreadsheet, so I could get 100 rows of data, good timestamp and then 4 rows of header information more than 100 lines of timestamp and then 4 header lines and so on.  I have been using the feature to add the entry in the spreadsheet, which I think is part of the problem.

  How can I get waveform data to write continuously in the spreadsheet and write only once the header information?

  I have attached my code and an example of the header several write the problem.

  Thank you!

  He removed a + 1 function after that loop to the bottom left of the VI.

  This is the VI saved at 8.0 LV.

• Series read the analysis of the data works fine, but the polarity and point decimal placement does not

  I'm new to labview and work on a project that accepts the biotic data. I have read the information and analysis data correctly but when I try to set up the number the polarity and decimal pt do not seem to be correct. When the polarity is negative, a 1, the number that came out is positive. I have posted before and was invited to use the concatenation and the power of 10 and I wonder if it's okay. Should I be looking for the 1 (negative bit) and negate the number at the end before the release?

  I have another question: how to accept a number between the touch screen and just write this number in an output file? I searched in the help and online but found no example.

  Any help would be appreciated.

  I have included my vi.

  Thank you

  I'm sorry, I apologize. I thought since it was a new problem to a new position. I've corrected the problems mentioned in this post me. Oh and when I created the project/vi I created it as a touch panel.

  Thanks again.

• How can you save waveform data w / an iteration variable?

  No one responds to my messages, three Ive packed in the last hour, no one knows how to do this? I don't think that's the problem.

  Please help me, I need to save waveform data, however several times a second the user said, I have one already done 'iteration timer' but it does nothing.

  Please, if you can help me, I use LV8.5.1.

  Thank you

  (I am a very new user.)

  
  

• ORA-19846: cannot read the header of the data file of the remote site 21

  Hello

  I have a situation or I can say a scenario. It is purely for testing base. Database is on 12.1.0.1 on a Linux box using ASM (OMF).

  Standby is created on another machine with the same platform and who also uses ASM (OMF) and is in phase with the primary. Now, suppose I have create a PDB file on the primary of the SEED and it is created successfully.

  After that is a couple of log, do it again passes to the waiting, but MRP fails because of naming conventions. Agree with that! Now, on the primary, I remove the newly created PDB (coward the PDB newly created). Once again a couple of switches of newspapers which is passed on to the wait. Of course, the wait is always out of sync.

  Now, how to get back my watch in sync with the primary? I can't roll method until the required data (new PDB) file does not exist on the main site as well. I get the following error:

  RMAN > recover database service prim noredo using backupset compressed;

  To go back to November 8, 15

  using the control file of the target instead of recovery catalog database

  allocated channel: ORA_DISK_1

  channel ORA_DISK_1: SID = 70 = device = DISK stby type instance

  RMAN-00571: ===========================================================

  RMAN-00569: = ERROR MESSAGE STACK FOLLOWS =.

  RMAN-00571: ===========================================================

  RMAN-03002: failure of the command recover at the 18:55:32 08/11/2015

  ORA-19846: cannot read the header of the data file of the remote site 21

  The clues on how to I go ahead? Of course, recreating the eve is an option as its only based on test, but I don't want recreation.

  Thank you.

  I tried like below:

  1 a incremental backup of the primary of the CNS where off the eve also taken primary backup controlfile as Eve format.

  2 copy the backup of the watch parts, catalogged them on the day before.

  3 recovered Eve with noredo option - it fails here with the same error pointing to the 21 data file.

  OK, understood. Try not to get back the day before first, rather than restore the controlfile and then perform the restoration.

  Make it like:

  1. take incremental backup of primary SNA, also ensures the backup controlfile format.

  2. copy pending, get the location of the data file (names) by querying v$ datafile on the eve. Restore the controlfile ensures from the backup controlfile you took on primary and mount.

  3. Since you are using OMF, the path of primary and standby data file will be different. (/). If you require catalog data from the database files pending.

  (Reason: you restore controlfile from elementary to step 2, which takes place from the main access road). Use the details that you obtained in step 2 and catalog them.

  4. turn the database copy by RMAN. (RMAN > switch database to copy ;))

  5 Catalog backup items that you copied in step 2.

  6. recover the standby database using 'noredo' option.

  7. finally start the MRP. This should solve your problem.

  The reason I say this works is because here, you restore the controlfile to primary first, which will not have details 21, datafile, and then you are recovering. So it must succeed.

  In the previous method, you tried to first collect all the day before, and then restore the controlfile. While remedial classes, always watch seeks datafile 21 as he controlfile is not yet updated.

  HTH

  -Jonathan Rolland