Producer/consumer problem: several loops/queues

Similar Questions

• Shutdown producer/consumer problem

  Hello world

  I need to control one position with a controller of axes and save travel time of the position between two points. I use a producer/consumer model, but the stop key does not complete the program, the second loop is still running. I thought that hitting the stop button would create an error and end the while loop.

  Do you know where is the problem?

  Thank you for your help

  Your VI works as expected. Get rid of the misused sequence frames.

  The last image the question because the queue is destroyed if the two loops have completed. As the loop of consumer requires the queue to be destroyed to finish, this will never happen.

  Norbert

• Producer / consumer set loop of dynamic data item type

  Hey all,.

  I do a simple exercise of producer / consumer in a loop. In my loop of producer I audio Aqcuerir and in the loop of consumer I'm projecting on a chart

  Everything works as I had in mind, the only thing that bothers me is the way that I had to set the type of the element to the block "Get the tail" at the beginning.

  I knew no better way to get the kind of data that I used to just take an another "acquire its" Express VI and which hang. But that may not be the only way to get there, right?

  Note: I know that I might not need to use a producer / consumer design tend to do, but I need to get hold of technology for school work so I came with this exercise just to get a hang of it.

  Thanks in advance,

  Al.

  Al,

  You just need to feed the correct data type in this entry, which you did by getting the output of a second acquire its Express VI.

  You can also use the "Convert to Dynamic Data" function to do this.  When you drop to the bottom of the function, you will be asked to give the input type.  Tests I've done, it seems not to matter, but for example if you chose the entry to a single scalar type, you need to feed a digital constant (change to double type) in the entrance and use the output of dynamic data such as line item data.

  I don't like the dynamic data type because it is not very clear as to what it is.  Another thing you could do would be to use the "Convert from Dynamic Data" function to change the output of the VI of its acquisition to a different data type for more or less to avoid the original problem all together.

• export to spreadsheet - data 2 channels appear in alternation with loop of producer/consumer

  Hello

  I'm having trouble with the function "Export the waveform to the worksheet" - but it is not clear to me if the problem is with how I use the export feature or if I am wrong concatenating two waveforms of different modules of the series prior to export, or if my queue is wired incorrectly for producer-consumer loops.

  I use a hunts SMU-1073 with SMU-6361 and 4330 modules (tension and strain). I tried to change the example of the "entry analog cross synch" for use with a structure of producer-consumer (see VI below).

  The output of the worksheet contains a large part of the data in the string tension, followed by a smaller piece of data (with timestamp) strain, after which the alternate output data between data of tension and strain.

  Can anyone suggest where I could go wrong, or how I could solve this?

  Attachments do not work, so I'll try to post in an empty message directly after this post.

  Thank you

  Claire.

  That's what I thought.

  A number of wire.  -1 gives all the samples available in the buffer (which can be zero for some reason any).  A number will expect that there are many examples.  If the two readings can wait until they have both the amount of data requested.  This way, they will also have the same number of samples and be better aligned in the text file.

  Your loop will continue to run until you press stop or get an error.

• What is the fastest method producer consumer. Queue, RT-FIFO, event

  Hi all

  Another question completed for the pro:

  I recently inherited the labview code that uses RT-FIFO for the transfer mechanism in the architecture of the producer consumer.

  The code was first written in 3-4 years and is currently in LV8.6. It is possible that the reasons for the architectural decision no longer exists.

  I am qualified using a producer consumer queued architecture,

  I understand the RT-FIFO Architecture.

  I started using an architecture based on events from the user.

  (I have attached samples of each)

  I also see the existence of a priority queue

  Each method has its own capabilities and gaps, that hand, nobody knows the relative performance of each method.

  (Assuming that the only process)

  I would expect RT-FIFO to be faster, there seems to be a version of low characteristic of a standard queue.

  What is the perfornace hit to use a coding user-friendly queue more

  RT-FIFO description talks about commications between the time-critical and lower priority threads.

  Until today, I thought that the queues had the same capacity.

  

  I've included an event method that I commonly use for review by peers and help from other users...

  It allows to:

  1. several producers with different types of data

  2. process 37 production order.

  3 allows asynchronous verification of functional notifiers such as stop, start and abort.

  4. in a system not real-time, it can include interactions of façade.

  What I do not understand on this subject, that's what are overhead or thread priority changes that may occur using this architecture (it solves a lot of problems for me).

  Thanks in advance,

  Hi Timmar,

  Here's a KB article on some frequently asked questions about the RT FIFO: http://digital.ni.com/public.nsf/allkb/7AE7075AF1B2C58486256AED006A029F?OpenDocument

  The more relevant question is #4, I posted below.

  What is the difference between RT FIFO and queues? 
  Functionally, RT FIFO and LabVIEW queues are two pads of first in, first out. However, here are the main differences between them:

  • RT FIFOs run deterministically in LabVIEW and evanescent code queues are not. This comes from the fact that queues use block calls during read/write to the resource shared, while RT FIFOs use non-blocking calls.
  • RT FIFO are fixed size while queues develop when items are added to them.
  • RT FIFOs will execute the code, even if there are input errors. They can (and will) produce new errors and spread the existing errors.
  • Queues work with any type of data, while the data types that can be used with RT FIFOs are limited. Generally any type of data involving allocations of extra memory can be used with RT FIFOs to preserve determinism.

  Let us know if you have persistent questions!

  Ryan

• Buffer could replace the queue in the design of producer/consumer model

  Hello

  I have a question to which the task of buffer to store the data and the queue is also of the same thing so we could use the inplace queue buffer in a design of producer/consumer model.

  No, these examples of buffer not almost equal to a queue, and never "replaces" queue at the producer/consumer.

  The advantage the most important of the queues for the producers/consumers (which none of the other mechanics buffer sharing), it is that it works activities to warn the reader that the data is available. So if you would simply replace the queue by mechanics of tampon too developed that you have attached to your last post, you will lose a large part of the object using producer/consumer.

  Thus, to compare the two mechanics:

  -Tail works activities, while the example of the buffer is not.

  -Tail must allocate memory during execution if several items are written in that corresponding queue. This also applies to the buffer (must be resized).

  -Given that the buffer is actually simply a table with overhead, memory management becomes slow and messy with the increase in fragmentation of memory. Queues to play much better here (but have their limitations, there also).

  -Overload of the buffer (the table manipulation) must be implemented manually. The queue functions encapsulate all the necessary features that you will need. So the queues have a simple API, while the buffer is not.

  -Given that the buffer is simply a table, you will have a hard time sharing the content in two parallel running loops. You will need to implement an additional charge using data value references to manage the buffer or lose a lot of memory using mechanics as variables. Lose the memory, you will probably encounter racing conditions so don't think not even on this subject.

  This led to four '+' for the queue and only a single point where 'buffer' is equal to the queue.

  Hopefully, this clears things up a bit.

  Norbert

• trigger several events to user in an architecture of producer/consumer

  Hi all

  I use a producer/consumer architecture, where the case within the property are selected with enums sent via a queue.

  Enums are queued in the producer, which is a Structure of the event inside a While loop. Then each of the events in the producer is associated with a case in the well (to make it easier).

  Now I would like to run several events in the producer, programmatically in a given sequence. The events involved in the sequence are basically all triggered by changing the value of a Boolean value (button).

  Please find attached a schematic representation of the sequence, I would like to implement.

  I heard of 2 solutions:

  -"Writing to the node (Sgnl) Value property of the variable [I] want change."

  -Dynamic user events

  In any case, I don't know how to make sure this is done for several events in a specific sequence?

  Thank you.

  Florian

  
  

• Producer consumer with the third loop model

  Hello everyone and thank you for looking at this.

  I have a problem that I thought for a while now on the execution of a third loop in a design model of producer consumer (with events).

  I use this type of model for a UI and am happy with how it works. However if I want to add a continuis loop model to test for example how can I control the loop?

  In my example (see table), I use a local variable to run them (or stop) the test and the same to close the application.

  I don't know why, but this feels wrong to me. Is there a better way?

  Thanks in advance

  Chuck

  Nickelback says:

  Is the problem with the consumer loop only runs when it receives a message from producer loops event.

  Nothing says that you can't have a consumer loop enqueue States to itself.  Of course, this is more in a State Machine in queue with the possibility for another loop to the States of the queue.

• Cannot terminate everything in a loop to the producer/consumer

  I have attached a simple vi which was built from the producer/consumer (events) model.  In vi I set up a counter.  I want to be able to complete the meter when you press the stop button.  This does not work as expected.  The meter goes to its full count before the program stops.  The vi works as expected when run in execution to highlight mode.  Cannot understand it.

  Thanks in advance.

  Race condition.  No matter what time something behaves differently with that highlight run it at full speed, and suspect it is a problem of synchronization due to a race condition.

  As soon as your producer loop has the command queued up, she is ready to handle the next event.  If you press the stop button, it is ready to deal quickly and the stem while the ends of the loop and Stop immediately gets back to false.  This probably happens before the loop of consumer has the opportunity to read the local variable of the button stop in the moment, it's true.  Have your consumer while loop redefine the Stop button to false instead ensuring consumer loop has a chance to see if it is true.

  

• error 1 to queue in a producer/consumer architecture

  Hi all

  I use an architecture-based on producer/consumer queue, as shown in the screenshot below (which is a simplified diagram of what I want to do).

  As you can see:

  1 / in the producer of the loop, I read data from two LV2: map Wafer and HAD current

  2 / in the loop of producer, these LV2 are used as output of a sub - VI, called 'Wafer map change. The Subvi, allows the user to change the 'Wafer map' picture indicator located in the loop of consumption, by double clicking it.

  3 / when the Subvi has run, it displays the picture indicator updated (Wafer card) and the new 'Course DUT' coordinates.

  4 / the two variables are grouped and transformed into a Variant.

  5 / the variant is then enqueud in the queue of the 'hand '.

  6 / this variant is converted from inside the loop of consumption, and photo indicator is unbundled.

  7 / Finally, the map LV2 Wafer is written and the modified photo indicator.

  This type of data flow worked earlier, but now I am facing the following error (it's my french translation):

  Error 1 occurred: Add an element at the end of the queue in GUI.vi of automatic Test Bench

  Possible reasons:

  LabVIEW: An input parameter is not valid. For example, if an entry is a path, it may contain a character that is prohibited by the operating system, as? or @.

  NOR-488: The command requires a PDC GPIB controller.

  I have no idea how it appeared. But now I'm stuck, and I would be grateful if someone can help me with it.

  Thank you.

  Kind regards

  Florian

  Your method to allow the judgment seems suspicious.  Say that there is an error in the loop of consumption.  This stops the loop of consumption and the stop button set to TRUE.  But the value of the stop button will not be read until the next iteration of the loop of producer.  So if you decide to hit the button on the Insert, the queue was already destroyed, then you will get your error.  And all these local variables just shouts "RACE CONDITION" for me.

  Get a mechanical action of the Stop button latch when out.  It is the default setting for a button.  Then place the terminal inside the event (which you already have).  A REAL outside this case, wire OR with wire error to stop the loop of the producer.

  You need to do is create a command to stop the loop of the consumer.  This order will be sent in the case of changing value of stop button.  You should probably send this command after the loop of producer, just in case where the loop of producer created an error.

  You can also use a node property of the button stop to set the Value property (signs).  This will cause the structure of the event to raise.  This will cause the producer loop stop if the consumer has an error.

• Timed loop in loop of producer/consumer

  Hello!

  I have a loop of producer/consumer LabVIEW program configuration to allow me to properly capture the images that are large enough (8MP) at about 14 frames per second (FPS). The program works very well when the consumer loop is a while 'loop' (recorded at 14fps without problem), but I wanted to do a loop timed, so that I can vary the FPS as requires it. A curiosity arises when I do that. Anywhere under 12 fps, the loop works very well and the data is saved correctly. However, when I bump it up to 13fps, the calculated consumer FPS goes haywire and starts to jump between 9 ~ and ~ 13fps (processing of data gets bogged down?). When I set the FPS at 14, the loop runs at a constant maximum 7 fps. Is there something I can do to remedy this situation?

  I have attached my .VI

  Thanks in advance!

  

  Palanski,

  Are you using LabVIEW Real-time? Loops clocked to a windows OS do really increase determinism more than a while loop with a wait until the next timer multiple. Before you change the loop of producer-consumer in order to include a while loop was programming works correctly? You can also vUtiliser the VI analyizer to see how long things take to run. I let the loop of consumer to the producer in the traditional game upward and change the FPS by controlling the timer to wait, after benchmarking your code, it should be done in the same way as you did for the timed loop

• State machine in queue with the producer consumer

  Hello

  I am trying to build a VI where the user allows some Boolean controls on the front panel.
  VI uses a producer consumer in which based on Boolean values clicked architecture.
  some States are queued one recorded in a table.
  After the user is done by selecting, Boolean values should get disabled and the table of States
  should be indexed one after the other.
  It is an attempt to solve the review model car wash.
  However, the VI does not generate the required results.
  Can someone help me please understand what is the correct way to this implementation.

  Thank you

  Its because you have wired the consumer while loop the first stop. Remove and in your loop of consumer, make a comparison of the States that you receive and if it is equal to stop, stop the loop of the consumer.

• Learn how to use queues producer consumer event

  Hi all

  I'm trying to understand the good programming techniques for the use of the elements of the queue in a producer / consumer event-driven program. I am looking for some demonstration programs have an idea of the functioning of these looops-based. Currently, I'm not sure on how to deal with errors that occur before an event from the queue (see screen capture below).

  If a queue receives an error, it seems that the queue item is never received. I have an OR statement to stop the producer loop when it receives an error message. However, because the question has never been in queue, dequeue in the consumer just loop element crashes then the consumer don't never closed loop the while loop.

  What are some good techniques to handle errors that are placed in a queue? I could probably cable a timeout on the dequeue, but I prefer not to use this approach if possible.

  Thank you

  
  

• producer consumer loop run only once?

  Hello here

  In my VI, the loop of the producer seems to operate continuously, but the loop of consumer only run once.

  I did not use producer/consumer patterns before, could someone give me some ideas why this is happening?

  My code is attached.

  Thank you in advance.

  Faouzi

  It would be the wrong choice to use a structure of the event into the loop of the consumer.  As it is configured, you must generate a leave mouse or mouse event enter on the graph of waveform for the loop of consumer to complete its first iteration.

  Remove the structure of the event.  you don't need to update a chart.

• Convert single while loop with variable Timing literal to the producer consumer

  I have a controller for a biological system that updates every n minutes or every minute 2n, under certain conditions. My app has a synchronization controller calculates if the current iteration is n or 2n and feeds the output of this calculation in a loop of "Timing" VI in my all. If I understand correctly, this is similar to the issuance of an order of sleep() in a language similar to C and should be avoided. I'm refactoring my code and I heard that they are well suited for this kind of things. Here's how it should work:

  1. Loop begins at the time T, T is saved.
  2. Schedule controller runs and calculates if loop will get minutes 2n or n minutes. This controller will take a number of milliseconds to complete, so we are is more to time T.
  3. Now that the update interval (n or 2n, let's call it u) is known, the loop must until T +u fill.
  4. The PDC is executed, but a number of milliseconds to execute.
  5. The rest of the time until the next iteration of loop should produce the CPU for other processes.

  It sounds to me like it's the kind of a real-time system, although as long as we are in the minute of the original deadline, there will be nothing wrong.

  What the producer-consumer loop would look like? Assumed that the synchronization and the main order controller are separate from the VI.