Circular buffer asynchronous read with crush

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• Circular buffer with reference

  I create two measurement systems that will enjoy air with instruments 13 and 10 respectively. I communicate with instruments through the series, MODBUS TCP, voltage and current. In order to synchronize the data of different instruments (which have their own data rate) in the stream, I need basically a circular buffer by instrument. I wish to add to each buffer circular instruments in a loop for each instrument and have a timed loop that records the data in a file by reading all the instruments circular buffers. Circular buffers must also be able to give me data that are not the most recent data.

  How can I create a circular buffer that I can add items to a loop and read another looping? I would prefer something but who uses a reference that I can pass both the loop of the instrument (producer) and save data of loop (consumer), like the queue works in Labview, I don't know how to implement this in a good way.

  Use LabView 2010 Fall edition...

  Thank you

  mrsound

  Native queues in LV 2010 allow you to create a circular buffer if you are using the antiderivative of Lossy Enqueue.

  Warnings:

  1. You must specify the size of the queue when get everything first, if you can not resize dynamically.
  
  
  2. To play the buffer, you can use the primitive that returns the queue information and wire a T in the items back? entry (very important to remember it). This will create a copy of the data in the queue.

• Combining a circular buffer with dynamic data

  Hello

  I am trying to save data in a test that surrounds an impact event to determine the period during which the acceleration passes a certain threshold. I want to record a second of data before and after the event occurs, I put the threshold crossing. The duration will be about 10-15 ms, so two seconds of data at 10 kHz will be a lot of data. I have my VI written so far to export the data from the buffer to an excel file, but is it possible that I could record an extra second of data and it concatenate into what I already have? I usually use the express VI of data collection for dynamic data collection and report generation specific excel live for static data, but how could combine the two?

  Any kind of conceptual thinking would be much appreciated.

  Thank you!

  What I've done in the past, is to use a queue of fixed size with the queue with loss to store data (is like a circular buffer).  Then, when the threshold is detected, recording a 1 second.  Your queue should now have 2 seconds of stored data that you can then write just to your file (use the status of the queue to get data without emptying the queue).

• Increase the length of size and recorder circular buffer

  Hello again!

  First of all:

  I have a problem with the circular buffer.

  I was able with a sampling frequency of 1000 Hz I used 6 circular buffers, each with a size of buffer for 30 minutes. It was no problem for the PC. I do not have such a high sampling rate, but I need a buffer size that is larger, something between 90 and 120 minutes with 8 pads. so I decided to reduce the sampling rate of what I need, it's 50 Hz. Because I reduced the sampling rate to 1/20 of the original sampling frequency I thought that a buffer size of 120 minutes should be possible.

  Now, after trying the new sampling rate, I still can't use the 8 pads with more than 60 minutes. Any ideas why I had this problem? How can I provide a larger buffer, no possibility?

  Second:

  I use the recorder for display. I would like to display voltage in the long term. With the recorder the maximum length is approximately 3.5 hours. How can I view on longer periods? What I need to display the length in days. Is this possible? Perhaps with the other modules or almost?

  That's it for now, thank you a lot for the useful tips.

  Good day!

  Good bye

  The maximum time width of the graphic recorder or Y/t diagram is a function of memory (RAM) on the computer, the number of channels to display and the sampling frequency. Dynamically, the memory is allocated to the maximum. To avoid using RAM available on the computer, DASYLab is limited to half of the memory of the computer.

  That being said... How you appear more time? You can reduce the number of samples using average or separate modules - in effect, reducing the sampling frequency. Alternatively, you can consider if the trigger on demand and a relay may be able to effectively reduce the samples for data to slow evolution.

  Some clients have two screens high resolution on a shorter and more low resolution over a longer period.

• Specify the end point for the digital using an output circular buffer

  When you use DAQmx and a NOR-DAQ for issuance of a digital signal using a circular buffer (buffer Renault). The program works and works, but when the 'DAQmx Stop Task.vi' function is called to end the task, he stops at the output buffering as soon as it is called and does not wait until the buffer pointer reaches the final value in the buffer. I would like that the program to wait until the buffer pointer is on the last value in the buffer, does anyone know how to specify this setting?

  If you need to stop on exactly the last sample output you will need a way to trigger the stop in the material.  The options available to you will depend on what hardware DAQ, you use, but here are some possibilities on the top of my head:

  1. set up a digital output redeclenchables task finished (not all hardware supports).  Set up a counter of output to issue a periodic trigger with the necessary synchronization signal such that the end result is a "continuous" digital output without interruption.  When you stop your loop, stop the task of counter - digital output ends his generation but the trigger signal will be removed and so it will not continue after that.

  2. If you have an unused extra digital output line, add it to your task.  This line should exit 0 all except the last sample.  Physically, this additional digital line in a wire line PFI and use it to trigger a meter output.  Have the output counter generate a single pulse of some long-term (long enough to ensure that the software can respond prematurely).  Use the output from the task of counter as a trigger of break for the task of digital output.  Do not start the task of the meter until you leave your loop.  Do not stop the task of digital output until you have detected in the software that the meter has been triggered.

  If you need to stop on approximately the last sample output, you could query the TotalSamplesPerChannelGenerated property after leaving your loop and only stop the task once it reaches a multiple of the size of your circular buffer.  This is no guarantee that it stops on the last sample (if you use a device on a bus with a latency higher as USB or Ethernet the non-determinisme would be worse).

  Best regards

• circular buffer USB

  Hello

  I wonder if it's possible a streaming of data in a memory connected to the port USB 9063 cRIO.

  My application is currently broadcasting data in a circular buffer implemented in the host Pc, using network flow. I need data from 24 channels sampled at 250 Hz for half an hour. This because sometimes the trigger condition is given a web service that is updated every 20 minutes giving the timestamp of the event. So, I use the timestamp to search for data in the buffer and remove it from there.

  This can be done by 9063. I withdraw my request for a host Pc and use the USB memory. Is this possible? I'm looking for an example, but it seems that there are no examples on the web.

  KR

  Davide

  You don't need to remove anything.  Say you name the files "Folder 1" and "file 2"(très imaginatif, je sais...). "»  I would write a sub - VI, perhaps called "Open Double Buffer" that:

  1. Opens the specified file (file 1 or 2 file - you need to keep track of who), using 'Open or create' so it does not matter whether the file exists or not.
  2. File Position value 0.  This effectively "deletes" all the data already contained in the selected file, combining the steps remove old and new of the Open.
  3. Start saving until it's time to buffers to Exchange again.  Close the file and quit.  The appellant then rocker pads and we call again (or you could do this with a reentrant call...

  Bob Schor

• 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

• Difference between waiting occupied buffer and read by the wait of the other session in 10g

  Hello
  
  Can someone let me know the difference between waiting occupied buffer and read by other session wait in 10g
  
  Thank you

  http://download.Oracle.com/docs/CD/B19306_01/server.102/b14237/waitevents003.htm#sthref2988

  
  buffer busy waits

  Wait that a buffer becomes available. This event occurs because a buffer is either be read in the buffer cache by another session (and waiting for this reading end the session) or the buffer is the buffer cache, but in an incompatible mode (in other words, some other session changes the buffer).
  

  http://download.Oracle.com/docs/CD/B19306_01/server.102/b14237/waitevents003.htm#sthref3159
  
  read by another session

  This event occurs when a session requested a buffer that is currently being read into the buffer cache by another session. Prior to version 10.1, expected for this event have been grouped with the other reasons for waiting for the buffers under the event "wait occupied buffer.
  

• Global variables for circular buffer

  Hallo!

  I have another question:

  I need to have a variable circular buffer size. So I want set size circular buffer by a global varable.

  Is this possible? I tried to use the global variable like {VAR_01} to insert in the field that you want to the memory size circular buffer, but dasylab puts only a zero in the field.

  Thank you and have a nice day.

  Hilby

  Unfortunately, it is not possible to have a variable size buffer. Right-click in the textfield corresponding: the shortcut menu does not show an entry to select the global variable from a list.

• Code example for single asynchronous reading of multiple waveforms

  Hello

  I looked around but have not been able to find the code example for single asynchronous reading of multiple waveforms.  Could someone point me in the right direction?

  Thank you

  Dale

  Hi Dale,

  Have you looked at the code using .NET Framework DAQmx example? It shows this code:

  class DAQmxAsyncRead
  {
  private AnalogSingleChannelReader reader = null;

  public DAQmxAsyncRead (task t)
  {
  Create the drive
  Reader = new AnalogSingleChannelReader (t.Stream);
  Acquire 100 samples
  Handful of IAsyncResult = reader. BeginReadMultiSample (100, New AsyncCallback (OnDataReady), null);
  }

  Public Sub OnDataReady (IAsyncResult i)
  {
  Recover data that has been read.
  At this point, all that occurred during the asynchronous read exceptions are thrown
  Double data = reader. EndReadMultiSample (i);

  You can call the method BeginReadMultiSample here once again
  }
  }

  In addition, this article: http://digital.ni.com/public.nsf/allkb/485201B647950BF886257537006CEB89?OpenDocument talk about different causes of the reserved resource error.

  Kind regards

  Alexandra Valiton

• Implementation of the circular buffer for LabVIEW 8.5

  Greetings,

  Several weeks ago, I downloaded the application of a circular buffer for LabVIEW 8.5 of ni.com. The current Web page is:

  http://zone.NI.com/DevZone/CDA/EPD/p/ID/5883

  Unfortunately, this Web page has been updated since then and the files available for download (swcircularbuffer1.0.19.zip) are for LabVIEW 8.6.

  So my question is: where can I find the application of a circular buffer for LabVIEW 8.5?

  Thank you very much!

  Telmo

  The library in 8.5 is attached.

• When the function insert card reader with windows asking to format micro card?

  Hello, I have problem of a few days.when ever I insert the card reader with micro SD card windows asking to format...
  It is not happens with a single card, any micro SD card, I have insert Windows you want to format... but the card worked perfect in telephony, mobile and other things...

  I also try to use the same card reader & card in different windows 7 PC... It's working perfectly... .so help me with this...

  Hello

  Method 1:

  Follow the link below, run the fix it tool and check if it helps.

  Hardware devices do not work or are not detected in Windows

  http://support.Microsoft.com/mats/hardware_device_problems/en-us

  Method 2:

  1. check if the device is detected in Device Manager. Follow the steps to go to the Device Manager

  i. click on start, type devmgmt.msc and then on enter.

  II. research the name of the device

  If the device is not detected in Device Manager, and check if it is the hidden device.

  i. click on view under view hidden devices

  II. develop all winks in Device Manager

  III. there would be multiple entries in the device in gray Manager uninstall all entries shaded under all the winks and then restart the computer and connect the external device to the computer and check if it works

  2. install the latest drivers from the manufacturer's Web site and even ensure that the driver is compatible with the version of the operating system installed on your computer. Check if it works

  Links: http://windows.microsoft.com/en-us/windows7/Update-a-driver-for-hardware-that-isn ' t-work correctly

  Installing the driver in compatibility mode: http://Windows.Microsoft.com/en-us/Windows7/make-older-programs-run-in-this-version-of-Windows

  3. check with any other card SD one another if it is get recognized or detected or you can even check if the same SD card becomes recognized or detected on another computer

• I can't reactivate my e-reader with my existing Adobe ID and password which are both correct. I alwayss get the message "the server activation Code error: E_AUTH_NOT_READY" what kind of problem is this and what is more important, how can I resolve it quic

  I can't reactivate my e-reader with my existing Adobe ID and password which are both correct. I alwayss get the message "the server activation Code error: E_AUTH_NOT_READY" what kind of problem is this and what is more important, how can I resolve it quickly. I'm on vacation and you want to read. Thanks for the quick response.

  Yes, actually I talk about digital editions. Do you know how to solve the problem, as stated in my first mail of Digital Editions? Thank you for your kind cooperation.

• Problems with the graphics, as well as circular Buffer

  Hello

  I am having several problems with my chart. Basically, every time I move the Panel before or shake it, data do not appear to be connected and it screws to the top of the chart.

  Second, whenever my buffer fills, 50% of the time, it is this line that appears at the end of the graph at the beginning for a fraction of a second. I do not understand why it would happen only sometimes however, because many times the buffer fills, but this does not happen.

  If anyone has had this problem before and knows a good way to fix it, it would be appreciated. I tried to see and undefer updates to the front panel, but that did not help my graphic. Thus, my CPU usage is quite high.

  I don't know the details of the Galil motion card, but looks like you he might order from the UI thread. When you hold the mouse on a border of window in Windows, the user interface thread is not available for a period of time, and the call of the DLL just hangs. If you do not order the Galil with a DLL, see if the DLL is set to run in the UI thread (it will be orange.) This is the default value; LabView assumes that your DLL is not thread-safe if you identify exactly what. If the DLL is thread-safe, you can change the configuration of appeal to let it run in any thread.

• Visa series parallel read with arduinos, data are delayed

  Hello

  Currently I use two arduinos asynchronous data read from sensors of temperature and humidity. Each arduino send back 4 floats, separated by commas, with a stop of "\n" character In labview, data gets broken upward and then pushed to live plots. In addition, the data gets written to a file - arduino #1 and #2 Arduino have their data sent to different files. It is important to note that the arduinos have different rates by which they send data on the comms series. Ideally, we would like that the data of every arduino to enter and update locations independent real-time each other.

  I'm having a problem where data do not seem to be displayed in real time. I can touch a thermocouple and then ten seconds later, the temperature will change. This delay seems to grow over the short program, which is a problem since we use a direct result of the plots to determine when to start various processes of cooling.

  I wonder if due to different data rates the thrust arudiunos, if there is some kind of buffer somewhere that has a "backlog" of the fastest arrduino data and must wait for the slower arduino data until it does nothing. It is obviously a problem of data flow, but I'm pretty green with LabView and was looking for some advice or pointers. I want to mention that the arduinos send data quickly; they send every two seconds or more.

  Hello MrScientist,

  can you please try to use two separate while loops, one for each COM port, because if they're in the same loop, it can happen that they block each other.

  A second option is always read all the information on the COM port and made a ring buffer and filter information of these buffers.