Leave a consumer while loop

Similar Questions

• What is the best way to run multiple instances of the class containing infinite while loop?

  Hello

  I have a several instances of the class (say a, b, c,...) that have the same parent and I want to run the same methods overridden to all instances in parallel.

  For example:

  a.init ()-> a.run ()-> a.stop ()-> a.run ()-> a.stop ()->

  b.init ()-> b.run ()-> b.stop ()->->->

  c.init() ->           ->             -> c.run() ->               -> c.stop()

  ...

  See the attachment for more details.

  The problems are now:

  1. the 'run' - method does not return until it receives the external trigger

  2. everything to run methods return in a different time

  1 chip means I can't use autoindexed for loop because in this case b.run () will have to wait before the end of a.run (), right? Is it possible to run to the loop in parallel?

  2 chip means that an object must be able to run and stop independently from others.

  What is the most elegant solution? The solution copy - paste in the attachment works for 3 instances, but there are currently 10 and more is coming.

  Juha

  In fact, what I wanted to know was "how to add the 'P' loop '... Easy, after you ask the right question.

  In the attachment, there is a test.vi that has two numerical indicators in a certain time-infinite loops. If I leave the parallelism, the two digital are incremented infinitely. If I don't allow parallelism, only the first is incremented (he never leaves the infinite while loop).

  To solve my original problem, I can make an init-start-stop branch within a loop-parallel-indexing for and make sure that there are the same number of instances of loop as there are objects in my array of objects (object array is an autoindexed in the loop for).

  Also good point about the vis environment. I should also add that.

• Leave a while loop

  Hello

  I have a while loop that I want to go out with a stop on the front panel.

  Here is a bit of code:

  

  As you can see the code in the while loop is processed by filling four sub .vi.

  I found that if I press the button to stop at one point, the computation of the 4 sub fired then the other while loop will pass and not out at the end of the calculation of the sub 4. screw.

  What is the way to get around this please? I realize that the help of the fixed stops on the front panel is not recommended!

  Thank you

  Daniel

  Fact

  

• How to increase code efficiency in a while loop (using PXI5105 for sampling outside signal digitalizer)

  Theoretically, we want the PXI-5105 (digitizer) have 302 record with each record has a 1260 sample (the save operation is inside a while loop) in approximately 30ms, however we have found that for each period (30ms), the PXI5105 only perform about 10 records. It is so wired. I wonder if the operations inside the while loop consume more time (for example 3MS), so that he cannot have 302 records even the PXI-5105 have 60 M/s speed of sampling. Is it true, you can find my labview code and if possible can you give me some suggestion in the most short time of operation of the loop.

  

  Please find attached labview code.

  Hi g_l_g_s,

  The digitizer PXI-5105 acquires data at the speed that you specify and stores the data in its memory embedded (up to 512 MB). The data is then sent to your computer when the Multi Fetch Cluster.vi is called. In VI that you posted, you are only fetch record during each while the loop iteration. If you want to retrieve 302 records you will need to specify 302 files in the horizontal Timing.vi to configure. For more information about scanners, you might find the DevZone, hereuseful.

  To determine the amount of time it takes for each while the loop iteration, you can consider using the structure of code in the example comparison community calendar, which is located here.

• Can not on the button while loop

  Hi all... hoping to get a few design tips as I am very, very new to LabVIEW. I got a project that someone else had started and I've encountered a problem that I don't know how to solve.

  I'm using LabVIEW version 8.0.1 and I think my problem has to do with the help of DAQmx in a while loop. In "Working.vi" (including the Sub - VI 'Temp data to CSV.vi'), I copied - and stuck the while loop in a vacuum VI for testing. In this VI, with nothing else, it works - slowly, but it works.

  In the real VI, I can see the data of temperature updated every 4 seconds, so I know that the program is not frozen or something like that. However, by pressing the button "Return to main Menu" does nothing - the image of the button does not show that it is to be depressed, regardless of how many times you click or click and hold the button. I've attached a screenshot of the while loop inside the real VI; I prefer not to fix the real VI (especially because it contains references to many of the Subvi, and it is not currently contained within a LAW degree).

  I'm this coding the wrong way? I have the feeling that it might be caused by my settings DAQmx (continuous samples, 2 samples to read, 250 mHz). The very low rate would be the cause? Is there a better way to have readings of temperature taken every 4 seconds (approximately)?

  You have your case of event the value "lock the front panel" until full?  If so, then no other presses the button will be recognized until the ongoing case event complete.

  It is never a good idea to have a code in an event business that takes a long time to run.  It will make your UI seems to lag or even functional.  Any time I see someone with a while loop inside a case of the event, I'm afraid.  (By the way, I am also concerned all nodes comments hovering over the structure of your event?  What are doing?  Why some operate on the default data?)

  In general, events should take is no longer running then what ordinary person could be expected until they feel like the user interface is delayed.  Perhaps at the top of 1-2 seconds.  You should look at a model of design of producer/consumer with events.  The structure of your event should respond to UI events, then pass orders by a queue path to the part of your program that does the real work.

• 2 while loops can work at the same time?

  I have two while loops in my program; We can read the data and the other does nothing until I hit stop on the first. I want the first and the second to run out of the time constraint, I have for it when I hit the Start button to always run. I use a DAQ and transfer data from one to another while loop. See the attached file.

  Main issues:

  How to tie the Start button?

  How to get the second loop to work with the first?

  Thank you

  Your problem is that the loops are dependent on the data.  If you want to run two loops at the same time, they cannot have wires linking one to the other.  Focus on the architecture of producer/consumer .  It uses queues to send data of a loop to the other.

• I can constant maniuplate outdoors to separate while loops?

  What I want to do is subtract the constants incrementing in while loops 1 & 2. I removed the meat of the code, as it would get in the way of the question. Basically, a value is read (outside the structure of the case) each time, iI want to increment the "number of times read. The same thing happens in the second loop (they are basically independent of each other). I can't escape outside the while loop because the code never leaves the loop. I use a global variable? Thanks for any response.

  

  You will need to put in globals or functional globals to make your available outside your earrings acquisition counter values.

  You'll need a third loop at the same time to do the subtraction of values you have in your globals.

  You can also examine the help of queues and the authors of notifications.

  Another way to do would be to unstack a notifier received notifications whenever you receive a tag and then have a processing loop that manages the authors.

• How to set up the execution in a way independent while loops?

  Hello

  I hope someone here can help point me in the right direction for that.  My system at this stage is still quite simple, I just data collection of 2 resistance probe and a pressure sensor, their output in the Panel before and sometimes to write.  I have put architecture in place to call parallel loops running at the frequency I would ideally like to do.  that is, I want the RTD to update every seconds and the pressure transducer for updating chaque.5s, I want to write to the file at a rate defined by the user and I want the Panel before updating a half second (correspondence with the pressure transducer).

  Now, in the structure, I wrote, it should run all the while loop once before it can restart the sequence.  Technically, the code works, but it takes ~1.5s to the RTD to collect and update and so the whole VI takes ~1.5s to complete.

  I don't care if the RTD is slow to update, but as I use the sensor as a gauge of the cell pressure I need to know at a high frequency that the pressure is in the cell, and I don't want to wait 2 seconds for the information.

  I know I'm starting to get into a much more advanced architecture for this and ive spent the last googler 6 hours trying to find a procedure for how it works but I can't figure out a way to have the whiles stop waiting for RTD loop finish.  I guess that this is to divide the VI in several screws and construction of a library, but the resources I could find about it were not very useful for a beginner like me.  If someone could point me in the right direction on where I should look then that would be great!

  Thank you

  Zach

  Zach,

  Because you created the tasks of data acquisition elsewhere, we do not understand how you have set up. Continuously, starting and stopping tasks may be slower than setting up of a permanent task and let it run.

  You have not indicated that you use the DAQ hardware.  It is often better to leave in the DAQ hardware clock set ignition rather than rely on software distribution. The pressure loop reads 1000 samples at a time and calculates their.  If you're not sampling at 2000 s/s or faster, the loop ends late due to waiting for data.  In two loops DAQ, you do not use the calendar information.  Acquire the data in tables rather than waveforms.

  The Dequeue functions in the loop at the bottom have no wait times for this loop will not iterate until all three queues have data. As the pressure loop runs faster than the loop of RTD, the queue of pressure slowly fills.

  The upper and lower loops are vying for the data.  The preview queue item does not delete data from the queue, but the functions of the Dequeue elements in the loop of the low fact.  If data is deleted form the queue before the upper loop resembles it, it will never be saved. With your installation there is no way to ensure that you get all the data or that you do not read and record the same data more than once.

  You don't have anything set up to stop one of the loops.  You use the Cancel button to stop your VI?  If Yes, STOP! Other aprticpant on the Forums said: "using the button abandon to stop a VI is similar to the use of a tree to stop a car.»  It works, but can have unintended consequences. "Things like closing of files, freeing up the queues, by closing the task of acquiring data, and other things can occur when the program is interrupted.  You do not shut down your computer by pulling the plug.  Stop your program also neatly.

  Ok.  I have highlighted some of the things that can keep your program to run as desired.  What can you do about them?

  1. you probably don't need call loops.  Normal so the loop should be good enough.

  2 put a stop button on the front panel. Put the terminal in loops (bottom) and connect it to a function to send a Notification and the status of the Terminal loop (stop sign).  Put wait Notification functions in each of the other loops.  Put a period shorter than the time loop minimum on all of them if the lops can work.

  3. see the comments above regarding the DAQ bed material.

  4 use the Dequeue timeouts to adjust the pitch of the loop the loop where the data is used.  Also make sure that all data is removed.  You need to think about your time together and what are the bottlenecks.  Except if you expect this system to grow to much larger dat sets, I probably acquire ALL data (pressure and RTD) at the same rate and reduce the displayed amount by the average like you do for pressure data now.  If you want different final data rates, just average different amounts of data.

  5. it might be useful to learn how to work the State machines.  Display, averaged and recorded files could be managed in a loop by a simple state machine while allowing for more flexibility in the calendar.

  6. Another good reason to consider a state machine is that initialization and shutdown processes can easily be handled in the corresponding States. At this point you do nothing with errors. A state machine would enable you to handle errors (for example, the cancellation of the selection of the user files) without stopping the program.

  Lynn

• While loops and event structures

  Is there a problem using more then one While loop with an internal structure of the event, in a single VI?

  In my (only a partially attached printscreen) VI there is more then 2 all in curls with a structure internal even who controls a different devices.

  Event structures are being controlled by a box structure.

  From time to time the VI gets stuck and resetting local variables.

  

  Hello

  Using two while the loop is not a problem, it depends on how you structure the code.

  Generally, we use two while loop for Producure-consumer, master - slave structure type of applications. Try to use the structure of State machine inside while loops, see standard state machine examples in the palette of NOR find example.

• To use or not to use: while loop?

  Being relatively new to LabVIEW and excited by the event programming Structure makes me think that a While loop should almost never be used.

  A While loop uses "polling" to see if a condition is fulfilled or not before you stop the execution, which eats memory. (No pun intended) while event Structures

  don't constantly gobble up CPU memory and waiting for something to happen, and then runs.

  Can someone give me a simple and good example of when it is appropriate to use a While loop? Do not hesitate to talk about certain situations more complicated, requiring a While loop

  which cannot really be addressed with the programming of the Structure of the event.

  While loops and structures of the event go hand in hand. You almost always want to place the structure of the event within a while loop. If you do not you will serve a single event. The while loop will allow you to repair all the events. It is important to note that when there is no event loop will not be doing anything. He will be inactive and essentially no time consume CPU. The structure of the event will have to wait for the next event.

• Nested while loops

  Attached is a very simple with two nested all VI in loops and two buttons on the front panel.

  1 button, when you press left the inner loop.  2 button pressed leaves the outer loop and the program must end.  I put in a probe at the end of the outer loop and of course a REAL will to the terminator when I press the 2 key, but the program does not stop.  Apparently, all inner loops must be completed prior to the outer loop can terminate.

  Obviously, someone at NEITHER took the decision to design a long time ago, but the rationale is intriguing.  If one end of the loop becomes a REAL it must end, no?

  Although the example is trivial, the problem that it illustrates is a real for me.  I want to offer a panic button stop is a vast and complex and I don't see how I can do with things as they are.

  What you see is the result of the dataflow paradigm used by LV as you said, all the code inside the loop must complete / finish before the outer loop stops.

  Providing one Stop button to stop all in one comprehensive program can be a complex task. The key issue is that EACH loop, function, sub - VI, case structure, structure of the event, the structure of sequence and so on... must stop to stop the loop.  If you have something like a file entry or a reading of GPIB instruments which take 100s of milliseconds or seconds to complete, the shutdown will take at least that long process, assuming that the tedious node was running when the judgment was issued.

  One other point: you put inside terminal 2 touch it the case of the event that responds to the key. Which ensures that the button will be read so the mechanical action works as expected.  With her out of the loop it will only play once.

  A registrant can be used to 'spread the word' when it's time to stop.  The time-out he will keep waiting forever and will also allow the other parallel inside code while loop to run during waiting for him.

  Lynn

• How to acquire a position of the data series in a while loop that generate a position once a time in labview?

  My program is complete in a while loop. Once it runs, it will use kinect to keep my data of position of the head, so it will generate a position once. I want to reach 5 positions and can calculate 3 speed and acceleration 2. How can I get 5 times while it generates 1 time?

  If your data are made at the edge of the while loop and you right-click where the wire exits the while loop, you can select "Enable Indexing" that will produce a table of the data received as large as the number of times in the loop. You can also check the "examples: help find ' ' Producer/consumer', which will allow your receiver (producer) loop to get the data and send it to a processing loop (consumer).

• For loop within a while loop

  I have for loop within a while loop... admission to the for loop N comes from the VI selection... the while loop I a condition essentially statement it stops just after to finish all the iteration in loop...

  Entrance to the N loop is bascially driven by a local variable... that's the problem Iam having:

  When I press the Start button to run the program... regardless of the output of the select VI is gives the N of the for loop, then the loop starts and then ends in place... and when the output of the select statement takes a different value (the N of the loop for) loop not work until I restart the program again... What can I do so that the for loop runs again for another value of N, the RUN program button is enabled.

  1. clean your diagram.  Style guides suggest keep the pattern of a single screen.  With a little effort, I was able to get your DB less than 1600 x 1000 pixels.

  2 then I can see (some) it happens all at once. This thing does nothing?

  3. local variables can lead to race conditions.  Output in Angle position may be a race condition, although is probably not what you wanted to do.  What does the wired local time at the moment present terminal meter? (Ooops! Two controls with the same name - which can be quite confusing as well!)  If you need or want two components of façade having the same text, use the legends.  Make the labels is different so the comic is more readable.

  4. having more than one Dequeue function on the same queue will lead to unpredictable results.  When an item is removed, it is removed from the queue and is not accessible to any other Dequeue function.  In parallel loops, you have no way of guessing which Dequeue will seize any particular element.

  5 use Boolean reverse instead of Select with wired False to true and true cable at the entrance to false entry. Better, just make the case of forgery in the structure of the case within the for loop the real deal. No required reversal.

  6. I was not looking for to determine the logic of the code within the structure of this case. It seems I could have posted a much simpler way to do this several weeks ago.

  7. use multiply from the Digital Palette rather than a node form multiply by 4 or 1.8. Uses less space BD and is much easier to read.

  8. as has been suggested, learn how to work the machine architecture and the State of producer/consumer.  They can make your life much easier.  Do not try to convert immediately to these models.   It's too much bite to at some point.  Learn how they work first.  Make a few simple examples.  Then rewrite this program in this format.  Probably faster than fixing what you have now.

  Lynn

• Code Golf: stop two while loops with guaranteed ratio iteration

  Proposal

  In the vein of the tradition of Perl, I would like to see if there is any interest to solve a few puzzles programming in LabVIEW. Can someone post a problem and define the rules to solve.

  Here's a question for beginning/intermediate to sharpen your "palette".

  Description

  With a user action, how you would stop two while loops such as the relationship between iterations is the still the same? Concrete to view this situation is to take action: both instruments use the same source of synchronization to take measures, but second divides the clock down so that it is a little slower than the first whole factor. For example, if the slower instrument is four times slower, then at the end of the VI, the slower instrument takes 100 measures the fastest instrument took 400.

  Rules

  • You can use vi.lib
  • You cannot include any other subVIs
  • Your solution should pass for loop1 interval as low as 25 ms

  Model (joint in LabVIEW 2009)
  

   

  If people are interested in this, then we will find a way to improve future problems. Please post your suggestions and criticisms, but only if you also post a presentation ;-)

  MacNorth wrote:

  [..]

  If we choose the first suggestions, the VI has yet to recover the data at different speeds. You can dedicate a loop for each instrument to disassociate a jitter and latency introduced by their connectivity or the inner workings. This adds a margin of safety when there is a conflict of thread and the pilot. You can also implement a simple counting as altenbach loop and renounce the multiloop complexity.
  [..]

  It is a very good point. But I wanted to make sure, you should / need to discuss the benefits, but also the disadvantages of the design. Implementation of an application is most often a process of 'special cases '. If a framework/design for a single application model does not necessarily correspond to another application.

  Designs are always strongly according to the requirements and constraints. What gives here designs will result in educational services, of course, but not necessarily as reference models for specific applications.

  Advantage of simple loop:

  • No synchronization between several loops required
  • Can easily implement any whole factor between services (quotent & function remains for a case structure

  Disadvantage of simple loop:

  • Take advantage of the multi core systems (at least not much)
  • Can easily run out of the time constraints (material not "not responding" enough, fast manipulation of data takes too long,...)
  • Code will accumulate within the structures of the case, where the readability could suff

  The advantage of multiple loops:

  • See essentially the disadvantages of single loop (several loops solve those)

  Disadvantage of multiple loops:

  • More complex, especially for the sync switch (not beginner friendly, requires a more/better design)
  • May contain easily questions source such as race conditions and locks

  A little side note:

  Even if the equipment works different acquisition rate, this does not necessarily that the software must use different rates for data extraction. You can use the same model of an hour, but get X times more values for the task faster than the slower running. The 'only' thing to care of are the sizes of buffers and bottlenecks in the data transfer.

  MacNorth wrote:

  [..] The best advice published OR shutter multiple while loops (https://www.google.com/search?q=labview+stop+multiple+while+loops) are laughable (and the 'solution' in my model). [..]

  No, it's not laughable. For many applications, this approach to shutter at the same time several loops running is OK. The constraint: only for simple parallel running loops.

  More complex loops (producer/consumer and similar) with the more complex data relationship ships require more valiant approaches such as queues, declaring events or user.

  My 5 cents only,

  Norbert

• Control of the event: how to stop the race while loop within a structure of the event

  Hello

  I have some problems with control of a while loop inside a structure of the event (see annex VI).

  I have 3 buttons (the "Start measurement, stop, exit the program"). When a measure is running, it should be possible to stop the measure by clicking on "Stop the measure", but it does not work.

  Someone at - it an idea?

  Thank you very much and best regards,

  Michael

  Hi Michael,

  create a process parallel to your measurement. You can use the design model "producer/consumer with vents. You'll find it with «File-> new...» ».

  Another possibility would be to remove the "lock frontpanel" sign, in the case of event start measurement.

  Mike