Reference to a while loop

Similar Questions

• What is READ the array returned by the DAQmx meter? How can I know the two functions DAQmx READ data stream in the same WHILE loop?

  I have a question about the order of execution.  In the WHILE loop, I have two things to measure, period and tension using the DAQmx READ functions for voltage and the meter.  In the end, I want to collect these data as points almost simultaneously as possible, as a pair and then send them together to another piece of code (not shown here) which them will result in some sort of command for an engine.  It would be run, and then I want to perceive the tension and the period at a time later and do the same thing.

  (1.) I'm a little confused on what the meter of the READ function is back because it's a table.  What is a picture of?  I thought that it was up to the value of the individual periods between rising edges.  The output of the counter 1 DBL d's a table. How many elements in this table, and what determines the size of this table?  Are the elements of the array the individual delays between the edges?  How many values are stored in the array by executing?   We take the AVERAGE of the last 15 items, but do not know if we are throwing some of the data or what.  How to understand the composition of this painting?  How can I change the composition of this painting?  Is it possible to measure only one period at a time, for example the time between TWO edges?

  2.) Will this WHILE loop execute as it gathers tension and a "period table ' (remains to be understood by me) by TIME running in a loop?  In particular, we want that the value of the tension associated with the value of the AVERAGE of the period "array", so we can use two data items to create orders of next control every time that the two values are reported.  The structure for the delivery of vi will be attached data in pairs like this?  I understand that one of the READING functions run not before the other function of READING in the WHILE loop.  I want that the period "means" and "strain (Volt) collected at the same pace. This vi will he?

  Thank you

  Dave

  Hi David,

  I suggest including the DAQmx Start Task function. If it does not start before the loop, it starts the loop and work very well, but it is not as fast and efficient. In the model of task status, task wiill go to run the checked each iteration of the loop and then back the time checked running when it restarts.

  The status of the task model: http://zone.ni.com/reference/en-XX/help/370466V-01/mxcncpts/taskstatemodel/

  Kind regards

  Jason D

  Technical sales engineer

  National Instruments

• How to run a while loop continuously without iterate loop inside the fi, a condition is met

  I enclose a VI that once the answer 28 comes the loop must stop and loop should continue an iteration. Can you show me a way for her

  You can stop the loop when a certain condition occurs: http://zone.ni.com/reference/en-XX/help/371361H-01/lvhowto/add_cond_to_for_loop/

  Add a register to offset for the while loop and to implement the feature as below:

  

• Control and Simulation in a loop / while loop with TCP/IP reading / writing of synchronization

  Hello, I have a problem with reading TCP/IP and written in two loops. The problem is NOT to get the two loops to read and write to and from the other. This has been accomplished. My problem is when I run control and the loop simulation on my laptop and the while on a RTOS remote on the controller on-Board of LabVIEW in a remote PXI chassis, the while loop the remote system running on four 4 times faster than the loop control and simulation on my laptop. In other words, for each iteration of the loop control and simulation on my laptop, there are 4 four iterations of the while loop on the remote system. I need to know how to get a degree of kinship (1:1) with these iterations of the loop. When I run a longer simulation in real time, say 10 seconds, the control and Simulation loop begins to slow, i.e. the simulation time slows down until it is no longer in real time and the "Late Finish"? Parameter is set to true and the LED lights and continues to stay lit. At this point, the system destabilizes due to what I believe is being well sampling rate too discreet and I have to end the simulation. How can I get a ratio of one to one between the loops and also to avoid slowing the loops causing destabilization?

  To give an overview of my application, I implement a control system in a network, seen in "image2.png". This is achieved using my laptop as a subsystem 1. Reference signals are generated from the laptop and the error signal is produced. Control measures taken and the control signals are sent via TCP/IP to the remote system. Position feedback is returned, and the process repeats. My system has Core I7 Procs w / 3 GB of RAM, up to 1 GB/s speed via ethernet and LabVIEW 2011 installed with all necessary modules and networking tools. The attached VI Custom_Wireless_Controller works on my laptop. The remote system I'm working on that has the 7830 NI R Series with FPGA card. OTN runs on the PXI chassis with an enbedded controller that has networking capabilities of up to 100 MB/s via ethernet. I use the FPGA for the acquisition of data and apply control signals to my plant. The plant is the PCE twist connected to the FPGA through the cable of the ECP - RIO of NOR. Subsystem 2 is this side of the CNE. The FPGA collects position, he sends to the controller via the network, receives signals from the network drive and writes signals to the plant power amplifier that operates the plant. This process is repeated and the VI and is titled Custom_Wireless_Plant.

  I appreciate the help really and look forward for her and for any question!

  Well, the first step is to understand what you have set up right now. Your control and Simulation loop on the side of the controller is configured as 'Runga Kutta 4' and you have a loop timed on the other side. In addition, you have the primitives of TCP/IP on the control and the Simulation diagram and means he will perform (a message) on the size of each minor step, which in your case is 4.

  So, you have two options:

  1. replace the Solver side controller Runga Kutta 1 (this must synchronize loops)

  2. hold RK 4, but create a Subvi around two primitives of TCP/IP and configure from the VI to run than the major (continuous) step-size. If you do it right, you should see a 'C' on the upper right part of the VI you have created.

  Please let me know if what I said is not clear...

• 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.

• Measurement of time in a While loop

  Greetings gentleman;

  I'm kinda new to Labview, and although I sought an answer without assignment, I wasn't able to find one.

  So here my question, I would like to know how I can measure the time a loop sequence, in other words, what time is my point of view VI to run the main loop together?

  A little explanation, the attached VI tries to be a Markov chain, it takes some values in the first case structure based on the previus loop, then, if the values are correct, it passes to the next step and so on. It's pretty simple, and yet, my problem lies in the measurement of time. Since it is a 'distribution', it would take infinite time to execute a simple loop if it does not fulfill the characteristics, but it is scheduled to meet them so an average time should work.

  So, if you look to the while loop, should the big one, I want to measure how long I take for a ride.

  Thanks for the help, I'd be happy to read some ideas on how to measure this.

  Kind regards

  IRAN.

  You will find examples in the example Finder OR by searching for 'speed test' or ' reference '.

  Essentially, you create a flat sequence structure inside of your loop. In the first image, you measure the current number of cycles. In the middle frame, you run your code. In the last image, you measure the number of cycles again and subtract the first number of this. This gives you the run time to execute the code.

  You can see a page of the community about it here.

  There is a high-resolution time tick count VI hang out somewhere which is great for benchmarking and improving efficiency, used instead the number of cycles (ms) primitive.

  Edit - remember where he was

  https://decibel.NI.com/content/blogs/EvanP/2010/10/04/tick-count-us--microsecond-timing-granularity-...

• Series of reading and DAQ in same While loop

  Hello world

  I have a while loop that has a DAQ reading and a reading series of VISA.

  DAQ readings slow while loop for series com & therefore the iterative nature of the measures to constantly check byte-by-byte (for the full range of the code: 22 bytes) does not work. (it will check 8 bytes, 24,.. etc. because more bytes is collected in a buffer before it can browse new loop.)

  Is it possible to synchronize these two data acquisition devices?

  Data acquisition speed is fast enough, so if there is a way to keep the series bytes in a queue and take only the first 22 bytes for every while loop iteration?

  Thank you for your help. I can't join VI, but I can give you a reference image.

  I recommend having separate loops of data acquisition and reading series.  If you simply connect the latest value, the local variable is great for sending to playback in series to the other loop for logging.

• 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.

• 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

• Why the execution time increases with a while loop, but not with "run continuously?

  Hi all

  I have a problem of severe weather that I don't know how to fix it because I don't know exactly where it comes from.

  I order two RF switches via a data acquisition card (NI USB-6008). One job at the same time can be selected on each switch. Basically, the VI created for this feature (by a colleague) resets all the outputs of acquisition data and active then those desired. It has three entrances, two chain simp0le controls and a cluster table, that contains the list of all the outputs and some practical information to know what is connected (specific to my application).

  I use this VI in a complex application, and I have some problems with the execution time, which increased whenever I said the VI, so I did a test VI (TimeTesting.vi) to determine where the problem came. In this special VI I record the execution time in a csv file to analyze then with excel.

  After several tries, I found that if I run this criterion VI with the while loop, execution on every cycle time increases, but if I remove the while loop and use the funtionnality "Continuous run", the execution time remains the same. In my high level application, I have while loops and events, and so the runtime increases too.

  I someone could explain to me why execution time increases and how can we avoid this? I have attached my VI test and the necessary subVIs, as well as an image of a graph that shows the execution time with a while loop and «run permanently»

  Thanks a lot for your help!

  Your SetReset_DO VI creates a channel whenever it is called.  And that you never delete a task.

  When running continuously, that it's as if it only runs once and LabVIEW has internal mechanisms to close references that will not be used again.  When a VI is used as a Subvi, LV does not know if she will be called again, and lacks these things until the first level VI stops. You have a memory leak.

  Just as you open and close your file outside the loop for, create your channel out of the loop.

  Lynn

• Possible timeout in VISA read/write in While loop

  As the title says, I have a while loop that is constantly written followed by reading using VISA read/write.  I'm waiting for buffer correspond to a certain one, which the true value would end the loop.  In this loop, I have an indicator showing how many times he runs. All of this is repeated in another while loop.

  My problem comes the counter arrives at 10, then stops at the "write" command.  Do not know why.  I tried to increase the time-out of the instruments, but nothing has changed.  I added a delay of 10ms in loop, which also has not changed anything.

  For reference, I use a tektronix scope series 3000 of the MDGS and checking its state of relaxation.

  You said chill to read earlier!

  But it is not supposed to have to write it either.  Experimentally, access all VISA nodes, right-click and choose the Mode of synchronous i/o.  Make it synchronous instead of asynchronous.  The watch symbol will disappear from the top right corner.  See if that changes anything.

  What kind of serial port are you using?  What is an integrated in the PC?  A USB to serial port adapter?  Makes the chips on that, Prolific and FTDI?  You can try with a different serial port or a brand of adapter?  A lot of people have had problems with prolific chips.  And I have also heard of people having problems using adapters who had fake chips in them.

• void / vi... read vi inside while loop

  Hello

  I'm new to Labview... My main Vi keep reading data from serial port and parks (in words) in a table (put all in a while loop)...

  The table is also inner while loop... Now I still want to analyze this (element by elemnt) table and create an another VI who takes this array running as input... so the new VI should simply have this table entry... but the problem is that I can't see the data running in new vi... .any suggestions... ??

  ebuckbuck wrote:

  Thanks Apok...

  I'm not sure hoiw reference books here as when I create refernce of table VI main (24 sep... (VI)... it does not produce yet of any substance in following VI (who called)... Attached are my two files... .and I just want my main VI as for the output as array2 Terminal...

  Thank you very much

  ebuckbuck

  in this example, we want to move an indicator (main.vi) digital of the second loop (sub.vi)...

  

• How to use count imaq objects in a while loop?

  Hello, I am using objects IMAQ County and works well, but when I use a loop and I want to change the picture that I analyze to see results instantly, the search box, and the locations of the remains of the objects in the picture, even if I return to the original (for example at the threshold) values, objects of the location and the green rectangle remains there as the next image :

  

  This is the pattern I use:

  

  I used this same setup with the 3D IMAQ view and it works well, I change the values and changes in 3D view so do I.

  I use unduly the IMAQ dispose?

  Thank you very much for your help and comments.

  Bene

  The problem is due to the way works IMAQ Vision: the thread of the image contains a reference (handle), to the image, not the image itself. Means that once an image has been changed somewhere, the mods are propagated worldwide.

  The solution is simple: just add an IMAQ clear Overlay immediately upon entering the while loop (and add a small timer inside the loop).

  As an example, see the vi attached.

  

• 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

• Updated entries on day of a Subvi with while loop

  Hi there guys! It's my first serious experience with LabVIEW, so the question may seem trivial to you, but it's not obvious to me how to solve this problem. So I do an installation that integrates a number of flow regulators, a temperature regulator, DAQ, some taps and a mass spectrometer basic tasks. All these must be automated using LabVIEW. I started by doing a VI for each separate task is going very well. Now I need to combine the latter in an experience of master VI, and of course I run into trouble.

  The problem is that I want of course to control this experiences with some selected buttons/dials/what is on the face before of the main VI. However, each of these VI runs a while loop in which fact acquisition of continuous/data communication / whatever. Of course, I want to change settings online. If I just naively tie them at the entrance to the Subvi these will be read only when the Subvi is started, not during each iteration of the while loop.

  I added a very basic example of the problem, so we are all on the same page. The main VI has a button, the State which should update something in the Subvi. However once the Subvi is started it takes control of the execution and the hand-VI seems to be ignored (appears to hang) even if the program has a lot of spare time to read the buttons and put on day of admission. What is the official solution for this kind of problem? My experience in programming that I prefer to keep the intact Subvi, so I can use it as a reusable standard library. Of course a similar question can requested the sub - VI output which will be updated only once the execution is completed (which is never during normal operation).

  PS. I'm using LABView 8.6 on XP

  The best way to set up a BT program must initialize first your settings, and then launch a while loop where you communicate/aquire data or whatever, then after the while loop is finished close and clean up your references.

  Inside the while loop, you can place your code in many of the screws and it is possible to run those in parallel, but I defenetly does not recommend the use of loops in slot face, especially without having to open the front panel or a stop test.

  If your code is completely executed up to your Sub - VI, the main.vi will wait for the sub - Vi ends before continuing the code.