Stop the multiple while loops in the acquisition of Vision

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• I want cRIO to start and stop the acquisition by push physical button on the cRIO, is this possible?

  When you use my cRIO 9024 on the ground, I prefer to be able to start and stop the acquisition with pressing a physical button on cRIO.

  I want to say I don't want it to be "as a start-up," I don't want cRIO to start the acquisition as soon as the power supply is ensured.

  Is this possible?

  Hi Cashany,

  you will surely find this switch status. But there are easier ways (but more expensive) for a button. Fiddling with a pen or a small screwdriver to switch USER1 is not what I call "user friendly"...

  -You have at least 2 voltage inputs on your module available. Use a switch voltage on the power inputs. Use a 'real' button!

  -You have an available serial port. You can set some pins on GND or voltage and check their status inside the cRIO/RT target...

• Judgment of multiple while loop running at different rates to stop using the single Boolean stop button

  Hello

  I'm on the block diagram of 4 loops, do different tasks. They are independent of each other, but need to see the unique front panel - some of the wonders of labview!

  Now, I want to have a unique stop button which will in fact be a back button to return to the main screen by stopping all four loops on the block diagram. I used the stop button (switch released) with local variable to stop the three other loops. He stops the vi but it is not a good stop vi to stop properly and the grid on the performance of the front panel. Now all loops run also at different rates, so it is not necessary that all loops are stopped immediately when one of the loop is stopped. Can't really think of a better way. All the ideas!

  Kind regards

  Austin

  Variables local is ok in this case, but you will need to keep the control in switching mode (no lock).

  A better solution would be to have all the loops as a structure of event all listening value stop change. Or have the Stop value change event generate a user defined output event or similar.

  /Y

• How to stop the acquisition with a relaxation with the NI PCIe-6323

  Hi all

  I wonder if it is possible to stop data acquisition or pcie-6323 with a trigger pulse the same way that I begin to acquire samples with a finished sample mode trigger pulse.

  Thanks in advance

  M.

  The samplesPerChannel that you can show what the sample clock configuration defines the total number of samples for the acquisition of finishes.  In your case, you will read the data previously triggered so permanently in force this setting really only sets the size of the buffer.  If you want to just be large enough to avoid overtaking (although...) If the window you buy is potentially very short, you might want to explicitly configure the size of the buffer to something bigger and maintain the value of samplesPerChannel down so that the reference trigger can be accepted earlier).

  The numberOfSamples you specify when you start the player defines the number of samples for the next call for reading.  If you can read the small windows of streaming data to avoid having a blocking with a large timeout call.  If you do not want to change the time-out period, it is a property of the DAQStream class.

  The "continuous" examples (e.g. this one) should show how you can read back data asynchronous as it is acquired.  Your configuration looks more like a "continuous" example

  Since you want to start and stop using the same line as the trigger, perhaps an alternative to the evolution of the default read pointer would be to set up a central task of analog input with a relaxing break.  The caveat to this is that the break does not stop at the task and as soon as the line goes back to you will begin to acquire the data again - I would say using a meter to separate groups of samples in the buffer zone continued.  If you wish to purchase multiple windows of data in short succession well, then I would go with that instead to avoid having to restart the task (and potentially Miss samples during the restart of the task).

  Best regards

• start stop multiple while loops

  I have a fairly large VI that works while several loops with the strutures case inside.

  I would like to be able to close and on all looped programmatically according to events. (complete cycle or cycle started)

  I need to store my data in a table, but whenever I turned off the while loop data I gathered is lost.

  It goes like this-measure analog voltage - put it in a digital indicator... now I want to put it in a table only once by my machine cycle.

  If the opeator push the reset button, the table is available for acquisition of report generation.

  Any help would be appreciated.

  Thank you

  It's here.

• HAVE multiple AO-synchronization-2 multiple while loops

  Hi all

  I want to characterize my RF circuit by using an additional narcotics control and map PXI-6229. I wrote a simple VI in Labview, which is almost similar to the example, multiple-HAVE-AO-synchronization, seen in LABVIEW. According to my VI, 4 analog outputs with different offsets dc, amplitudes and phase values must be generated to my RF circuit and 2 analog inputs must be acquired by this circuit simultaneously and continuously. But the problem with my VI is that I try to observe two diagrams at the same time to see the changes in signals generated and acquired. However, I don't see the two signals simultaneously. The second while loop, which belongs to the acquisition of analog signals, does not start while the first loop generates analog signals continuously. How can I synchronize these two while loops in order to observe the two parties in the diagrams?

  I have attached my VI.

  Thanks in advance.

  T. Eray

  Hi Eray,

  I will be brief and I'll keep it simple. If I understand correctly, you have trouble with the data stream in LabVIEW. When you work in LabVIEW, you must understand the order in which the blocks (functions/nodes/structers) are run in LabVIEW - stream. Each block can be executed just at the moment where there values on each entry. This means that if the 2 blocks are connected with a wire, the 2nd block waits until the first ends its execution.

  In your case, that means, this 2nd loop does not execute before the first loop (with the DAQ Assistant) ends its execution, because the son comes from the inside of the first loop, then they go to some DAQmx features and then DAQmx features they go to the 2nd loop.

  In principle, what you could do is to put the content of the first loop, where you prepare the signal generated in the 2nd loop. Good course without the DAQ Assistant. Instead, you can use DAQmx writing in the 2nd loop.

  Kind regards

  Martin

• Stop correctly with While loop

  Hello

  I can't stop the information that moves in stages with a while loop I created (see below). I joined the program (LabView 8.5) for reference, just in case.

  Currently, whenever I press the stop button designated for the control of the scene, the stages will not stop until the last part of the scene movement pattern is complented (in this case part 7 of the stacked sequence). Now, I have tried various things, but it was the best I could do to make the stage stop at all. (all other attempts resulted in a clumsy scene movement afetr the boss or not at all stop). Any ideas on what I can do? I'm positive that comes to a while loop on the stacking sequence was probably not a good idea. I also stacked sequences are usually wrong (or it seems) but I it is rather tedious otherwise.

  Thanks for the help, Amend sorry if this question seems pretty basic, I haven't used LabVIEW much until last week.

  It's one of the reasons why the stacked sequences should be avoided at all costs!   They can ALWAYS be replaced by a state machine with several advantages.  No. 1 among the benefits to replace a sequence of stacked with a state machine is the ability to STOP a stacked sequence between state transitions should complete each picture before stopping.

• Stopping at two while loops, running with queuing

  Hi all

  I'm using labview 8.2.

  I have two while loops in my code (called the main loop and the other average loop - seen on the screenshot file).  I just want to stop both the while loop at the same time (it's ok it the average loop takes a bit longer).  I use global variables to stop (as I have tried the local one, but I don't think that LabView sees in the middle of the subroutine).

  Please give me some suggestions on this.

  Is attached a screenshot and my labview code

  Using a ' functional global' is almost identical with a "global" variable Indeed, before the existence of "global variables", a functional overall, it is how people have this feature.

  The usual way to stop a loop containing a "wait for queue ' is to destroy the queue and use the error on the terminal of the 'expectation of queue' directly in the terminal of the judgment. In this way, you don't have to queue up some kind of end the command to stop it.

  Add a queue to destroy after the stops 'main while loop. Delete the global variable and the error from the stop "waiting in the queue" in the loop "average" it is wire terminal.

  General advice, always try to avoid using local and global variables.

• Synchronization of multiple While loops

  Hi all

  I work with 4 all in curls that are independent from each other that is, there is no data flow in one loop at the other.

  I noticed that every while loop takes different time to iterate.

  However, I want to while loops to begin and end at the same time after each iteration.

  How can I synchronize their?

  Thank you for your response.

  Concerning

  Aveo

  Hi Aveo,

  You can use a few 'occurrences', 'Notifier', or "Rendesvouz" to synchronize your loops.

  Or use timed while loops - they can work in harmony...

• Sharing data between multiple while loops, competitor rates

  Hello

  I am trying to Exchange data between competitor while loops running at different speeds.  What is the recommended way to do this?    In practice, I have 12 indicators and 3 cards I would update (on screen) in the slower loop, although the data acquired and stored on disk in the fastest loop.  The image below is a simplified version of what really works my candidacy.

  I currently use local variables and shared to achieve this.  I heard however that local variables are evil because of their use of memory (data are copied instead of who passed by reference).

  Thanks for your suggestions,

  Adam

  

  Hi Adam,.

  Yes, here you go.

  Mike

• 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

• While loops inside while loops, how to stop?

  Hey, I'm confused with a simpler question to multiple while loops. My goal: stop or pylone2, just jump out of the small loop and stay in the big one. and if I click on stop 3. the entire program would cease... How can I do this? The following script does not at all... Thanks in advance!

  Yes you are completely right Mike... now, I solved the problem with another structure of the event and the Boolean variable local... Thank you very much!

• Error with parallel while loops

  Hello

  I need to connect 6 different instruments gpib. I am using parallel loops, but the problem is when I try to open 2 or 3 Subvi simultaneously (the intstrument drivers), I just open one because of everything in a loop to run the Subvi. The program should be able to open all the Sub - VI independently.

  Can give you some ideas?

  Thank you

  A. Castillo

  Look at the detailed help for functions to notify.  Then follow the links to the examples included with LV

  Another problem that you have, whether you use your curls greedy or reporting or another technique, is to know how to stop your hand while loop.  All the subVIs must be called before the loop stops.  This is the fundamental paradigm of LV

  You will probably need to rethink your primary architecture to something that will actually do what you want.  Plan and design before your departure from the coding.  Note requirements for the program and determine which parts are dependent on othrer parts, then select a program architecture that can meet the requirements.

  Lynn

• While loop, wait for the function and the stop button!

  Hello

  I have a while loop and a stop button. Inside my While loop - I have a 'Wait (x ms)' function. If I press the stop button, it does not block the program immediately, he expects ms x then stops the program. How can I get rid of this?

  Thanks in advance for the help!

  
  

• Stop and start the task in while loop

  I try to start and stop an output meter (creates pulsed output) in a while loop and I don't know how this is possible. I have a while loop running who is taking measures from a digital compass. If my title is within acceptable limits, the outputs of the meter (2 of them to turn to the left and right) must be turned off. If the title is out of the acceptable range, let say too far to the right, I want to start one of my outings of the counter to activate the object to the left. The issue I am having is that if I put the block 'Start the task' in the while loop the system will try to start each iteration of the loop, even if it is already on. I don't know if there is a problem, but it does not appear effective from a programming perspective. I remember reading somewhere that stop and start tasks can really slow a loop. Any suggestions?

  I actually just to understand it. If you use some if statements and the "fact of task is" block you can make it work.