Stopping at two while loops, running with queuing

Similar Questions

• 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

• How can we enter and update digital panel forward when a young while loop runs?

  Hi all

  In my code, I have a while loop making quick gripping (sampling)

  How can I update other digital controls in the front panel when the while loop runs?

  right now, once I have enter a number in this digital control, the computer seems to be no answer to the elbow. Looks like the computer focuses on the while loop.

  any ideas are appreciated.

  Thank you

  Jack

  
  

• Two while loops in parallel - 2 does not run

  Hello

  In this simple configuration, there are 2 while loops:

  • 1st - for installation
  • 2nd - operation, where variable X increments

  The problem is: after 1st run variable X is not reset to X 0, if VI stops immediately after it starts.

  The reason - 2nd loop is not executed, X 0 if value is not propagated to X.

  Thanks in advance

  Pavel

  

  You want to first one case installation and after perform the different number of steps, based on the parameters for installation.

  A perfect place for one State (a single necessary loop usually) machine. You need an idle state when waiting for user input. After that the user starts the initialization state, which calculates the number of steps for other States required. At the end the system automatically moves back to the idle state, and waiting for the user to install and launch another race.

  No need to sequence meal structure at all. With a state machine, you can just do much more (like abandonment of sequence to Midway, is not possible with the structures of the sequence)

• 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

• problems of operation of two while loops in a VI

  Hi forum,

  I am developing a project for the acquisition of data continuously for two types of signals (voltage and temperature), each consisting of 20 channels. The sampling frequency is different so I used two call loops of different period to take account of the sampling frequency. It is within the VI that is deployed to the target device. On the host VI, I have two loops while put each containing a VI write_to_measurement express so I can connect the data to two different filepaths. However when I run the program, that a signal is registered correctly while the signal remains would have only one row of data. Looks like one of the while loop is only on the iteration while the other is running smoothly. This is an example of the famine of memory? How can I solve this problem! Any help greatly appreciated! Thank you!

  Vincent

  What asked Fan Ravens is why do you use static variable to stop the loop?  You do something remotely?  Simply use a local variable in your second while loop to stop him.  You need to change the action of the button stop, but that would be the way to do it.  Stop buttons are perfect for debugging and development, but generally I will use one other mechanism to stop the program runs outside the environment of LV.

• 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

• Stop the multiple while loops in the acquisition of Vision

  Hi, I want to close multiple while loops with a STOP. I use the software for the Acquisition of the Vision for the recording of multiple cameras and I would like to finish this record from all cameras simultaneously. I don't know how to do this since I am knew to LABView. I would add my VI here and maybe someone can help me.  Thank you!

  A local variable should be sufficient for your application. Read the following article:

  Parallel stop, while loops in LabVIEW with a stop switch

• For loop runs with the value of N unwired

  In this case will be a loop run connected to the loop N worthless? I have seen a few examples of the loop for run without a certain number of times set to be ran wired or for example a size of table or something like that.

  PauldePaor wrote:

  Here's a program I am and as you can see the image that the program runs without the loop N being wired. The program will run without problem

  As everyone else has said, you don't have to plug something on N.  If you wire up a table for loop for input "auto-index", the loop for will run automatically the smaller table size.

  Perhaps an example will help:

  

  This makes a loop on my table size (in this case, long of 5 elements).  On the edge of the loop for which resembles [] brackets, indicates that it is auto-indexé.  The loop should go through each item one at a time (1, then 2, then 3, then 4, then 5).

• Control 2 while loop and a queue

  Hello Mr President

  I need handel while loopps as they run in order. I can use the structure of sequence, but the question is in my program, I also have one already queued. Please help me how I can handel this question

  Thank you

  You certainly want a State Machine. You can't do what you want using a sequence structure, as you said. If you need an architecture that can operate several different cases in a certain order, but also to repeat the States if necessary.

  The Computer of State Simple model that comes with LabVIEW is really the best way for new developers to become familiar with LabVIEW using a semi scalable architecture.

  Here is a large example of the works of a state machine:

  • States: Init, slowed down, exit, DoThing1, DoThing2, DoThing3
  • Each State contains code that could take some time. Ideally, not too long because this is how long your code might not meet.
  • The idle state contains a structure of event for all of the user interactions.
  • The front panel has a button that says "do the 1 thing.
  1. Loop iteration 0: Application starts, the first State is Init. Init State made the initialization stuff and tells the application to go to the idle state when finished.
  2. Iteration of the loop 1: request goes to the idle state. He's sitting there, waiting for the structure of the event.
  3. Time passes, and then the user presses the button 'do 1 thing ". There is no code or minimal code, within the occurrence of the event. The output of this state of the event tells the application to go to the State of DoThing1.
  4. Iteration of the loop 3: Application passes to the State of DoThing1. Here, there is code that does a few things. The output of DoThing1 State tells the application to return to the idle state.
  5. Iteration of the loop 4: Application goes to a State of rest where he waits again to the structure of the event.
  • Each State can tell the application to go to any State they want. You want to reset? Return to the Init State. You want to put an end to the program? Go to the exit State. You want each State to start another (such as a sequence)? Have DoThing1 out of DoThing2, which DoThing3, which outputs Idle.

• stop another WHILE loop

  I have two while loops running independently.

  The first has a Structure of the event that controls the STOP button for a user by clicking.

  The second series a bed to a port.

  When I get an error messages entering the serial port, I want to provoke the other WHILE loop stop.

  What is the best way to do it?

  Connect a case structure wire to the error and write to a signaling value property of the button stop in the case of error.

• How to upgrade a shift with two independent loops while register?

  Hello everyone, I have a panel with two clusters with indicators control... a left and a right. I have messages from serial port, and I'm currently updating the left and the right within their own while loops. I have a single variable, which must be updated based on updates on both sides. Basically, I need follow the last selection update on each side... If I had 1, 2 and 4 on the left side and 3 on the right side... I would need to follow 4 was the latest updated the register shift variable for uses more in my vi. Can someone give me an idea how to upgrade this a variable based on two while loops that run independently in the same sequence context? Thanks in advance, cayenne

  Thank you both of you for the suggestion.

  I managed to find a way to get the values that I needed without EI... but I read the link to the Nugget in their subject, and I can't expect a use for them in the future.

  Cayenne

• Can someone tell me what's wrong with my loop of consumer queue or producer?

  A Labview engineer helped me with the overall structure of my program, made necessary by the rapid sampling rate data and post-processing requirements. He recommended the producer/consumer, loop and using one of the example (Cont CQI graph - int clk voltage) files to actual data acquisition. So I put the loop on foot and spend my two channels of data acq past in the loop of the producer. However, nothing is get picked up in the loop of consumer and none of my data gets displayed there.

  Someone wants to take a look and let me know what I am doing wrong?

  It seems that the only time where you have to write the data in the queue (in the loop of the producer), when you stop the DAQ while loop or the acquisition of data generates an error.

  You may need to place the element from the queue node in the data acquisition while loop.

• 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

• Two questions in table "While loop"

  Hello

  I have two questions about creating tables in while loops. I'm using LabView 8.5.1.

  In its simplest form, my current while loop (delay set to 0, 2 s) has 3 variables that have been changed by moving a slider. They are each sent to a line in a block of 'Building the table' (data type is DBL 1 d) - this table is then written to a spreadsheet file, such as the three values are written to a new line (one value per column) whenever the while loop runs.

  Question 1

  How can I add a column 'Time' in this worksheet? In other words, get at the present time the loop works since then, from 0 seconds in the spreadsheet, via the table block building.

  I can think of how to do this with a loop For, but given that the While loop runs through an unknown number of iterations, I can't figure out how to get the counter to work.

  Question 2

  How can I text column headings on the worksheet?

  Thanks for the help and if you need anything anyone stating, please let me know

  To answer question 1:

  There is a function of 'Elapsed Time' you can put as the first colum of the data.

  This then reformatted your spreadsheet as
  Time Data1 Data2 Data3

  Time Data1 Data2 Data3

  Time Data1 Data2 Data3

  etc...

  

  To answer question 2:

  Build a table of positions, then write this table in the file only once, outside the loop.

  Your table with the data and time will write inside the loop.