What is the queue?

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• 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

• What is a good way to use the queues for the model of consumers/producers?

  Hi all

  I am following the model of consumers/producers to use the queue to synchronize the following process: the producer is a loop to produce a number N, I will put each number generated in a table and after each 5 numbers generated, I put the table in the queue and pass it on to the consumer. I have to wait the use by consumers of the data and it will then remove the item from queue so that producers will have the chance to produce another 5 numbers. As I put the maximum size of the queue one, I expect that the producer and the consumer turns to produce / consume all five numbers and the opportunity to another. Here is my code

  

  When the checkbox is false, the code will be

  

  For the first 5 numbers, product will generate every thing right and put it in the table, and it's going to pass the array to the quere so that the consumer will have the chance to loop through the table. I except the procude loop will continue only when the queue is available (i.e. all items are deleted), but it seems that once the consumer starts the loop loop of the product will continue (if the indicator x + 1 and x 2 will be changed to numbers). But this isn't what I want, I know there must be something wrong, but I can't say it is.

  dragondriver wrote:

  As you say in 1, sequency structure to enforce the order of execution, that's why I put it here, in this example, the simple question, I replace the complete code with increase in the number, in the real case, the first markers + 1 and + 2 must be performed in this order.

  Mikeporter says:
  1. get rid of all the structures of the sequence. None of them are nothing but apply a work order which would have been the same without them.

  So even if you delete the sequence structure, there will be a fixed & defined order and it is because LabVIEW follows the MODEL of FLOW OF DATA.

  Data flow model (more precisely in the context of LabVIEW): a block diagram node runs when it receives the required inputs. When a node is running, it produces output data and transmits data to the next node in the path of the data stream. The flow of data on the nodes determines the order of execution of the VIs and functions on the block diagram (click here for reference).

  Now in your code, just remove the sequence structure will not make you order will be going to stay the same, but you need to do some very minor changes (as thread of the error in loop, before that he go to the node "Élément Dequeue").

  Come to the main point: it's a good way to use the queue for the consumer/pmodel that?
  The model you are using (and qualifying as consumer/pmodel) is much too deviated from the original consumer/pmodel which model.

  dragondriver wrote:

  For the second, Yes, it's my fault for delete, though. I'm actually the example of model of producer/consumer design pattern, but I do not pay attention to the while loop in the part of the consumer.

  While loops (two producers & consumers) are the essential part of this architecture and cannot be deleted. You can start your code using standard model.

• What makes "new queue path" to write to the File.vi worksheet? I need a better explanation than what is given.

  You are looking for assistance.

  What makes "new queue path" to write to the File.vi worksheet?  I need a better explanation than what is given.

  Thank you.

  You can call this function without wiring to a path of the input file.  If this is the case, the function prompts the user for input file using a pop up dialog box.  If a file is selected and you press OK, it is the path of the file that is out of the function as the new path of the file.  If you press the button cancel instead of OK, the "not a path" constant is the new output file pathname.  If the function is called with a wired file path entry dialog box appears, the same path of file entry becomes the new output file path.

• What is the difference between call queues and priority routing?

  and what is the difference between routing based on skills and the basic skills of routing?

  Suite...

  Priority Queuing - Set Priority step can be used to assign a priority (1-10), or increase / decrease. This allows for a given

  Contact (eg. calling) to priority over higher/lower than the other contacts that are in the same queue. In other words, the contact

  priority for all s CSQ for which he is put on hold. In the script, you must use priority defined stage to assign a higher priority or less in Call Queuing.

  Check the following URL, which described on stage "Set priority" to the title of the palette "CIM step Description.

  http://www.Cisco.com/univercd/CC/TD/doc/product/voice/sw_ap_to/apps_3_1/English/admn_app/step_ref/ICD.htm

• M127fw MFP: How to delete the print jobs in the queue?

  When I get an error message when trying to print, I keep trying to print.  This means that I can hit 'print' five times for the same document, because I hit 'print' whenever I think I might finally have something fixed.

  The problem is that HP never forget any of these applications - when it finally starts printing - it always prints every single job - meaning that I get multiple copies of jobs for which I got an error message.

  Where is the interface to view and delete these jobs? I can't find it on the printer itself.  Is there an interface where I can delete jobs in the queue?

  Go to devices and printers and double click on the printer icon. Now click on something like seeing what is printing a list of documents should appear and you can pass by and remove whatever ones you want.

• OfficeJet Pro 8600 Wireless Configuration - print is in the queue, then disappears. Do not print

  I just got the Officejet Pro 8600 as a gift and burden of implementing software and it on my wireless network.  When I try to print an e-mail or a coupon, the command changes to the printer and indicates in the queue. Then after a few seconds, the print queue (work) disappears without printing the document.  This command goes to the HP ePrint feature or the Officejet Pro 8600 network?  It shows the HP ePrint as being on USB.

  I have run all the Diagnostics, downloaded all the new software, software packages and updates.  I spend several hours trying to get to the printer.

  Thanks for any help you can provide.

  Hi @bksechols

  Welcome to the Forums of HP's Support.  I understand that when you send a print job to your printer Officejet 8600 to printing to the queue, then disappears without the printing of the print job.

  To help you, you please provide additional information?

  • How is the printer connected (USB cable, ethernet or wireless)?
  • What operating system do you use?
  • All print jobs fail? If Yes and you are using a Windows operating system, please try printing HP and Scan Doctor for Windows.  HP printing and doctor Scan is a free utility (tool) that allows to quickly solve common printing, scanning and connectivity problems.
  • When you send a print job are sending the address of electronic mail of the ePrint printer? If so please check The HP ePrint, print not print job if you send the print job using the print command, please see the document of your HP printer print jobs are stuck in the print queue .

  I look forward to hear from you.

• Windows 8, the error message indicates printer does not print. It prints, but does not remove the queues

  I use Windows 8 Pro, 64-bit on a printer of a6700y Pavilion with a printer PhotoSmart 310. When I print, I get an error message saying that there is an error, and the document will not print. The document prints correctly, but will not remove the file in the print queue... I have to manually delete the file in the queue. Of course, it's a software problem. How can I solve this problem?

  Hi eri2198859,

  HP has designed a quick and easy tool that diagnoses and solves many problems of printing, scanning and connectivity: The HP Print and Scan doctor. HP recommend you to download and install Print and scan doctor no matter what time you need to solve a problem with your HP printer from the link below.
  
  I would like to know what are the errors you receive?
  
  http://www.HP.com/go/tools

• Size of the queue for Signal form write XNET

  Hello

  I am using the XNET library to play a preset on an output signal waveform. I work with LabVIEW 2014 SP1, 14.5 XNET on a W7 Pro 32-bit operating system. I use an NI PCI-8512 map. This is my first app using the xnet library.

  In my test application, I give the user the ability to set the waveform to play. The total duration and the sampling frequency can be set. The output MAY report is cyclical, with a cycle time of 0.01 s (10 Hz). I chose to use the same frequency for example my wave form and writing of the CAN.

  I have difficulty working with the size of the queue. In this example, it's good but I did not really why. I tested different values in the size of the queue and 100000 seems to be good up to 60 seconds. But for the longest (about 5 minutes), this method is not good...

  

  What is the right way to work in this mode and how use efficiently the property size queue? Information and example of using software and hardware OR XNET are not very convincing...

  Thank you in advance!

  You can add several items at the end of the queue until the queue is empty.  So if you want to write 10,000 points, and your buffer is only 1000 points, then wait and monitor the number of messages remaining in the buffer, and once it is less than 100 say adds an another 900.

  I used this method for flashing on CAN and LIN.  I needed a way to watch specific at specified times images, and a single point of frame link would not repeat (which could write the same byte twice what would be bad) I could have made the rivers and used avoiding, but a better solution was to use queue and add more pictures at the end of the queue to try to keep it as complete as possible.

• Name of the queue in reentrant vi

  Hello.

  I have reentrant vi which generates the handles of the communication. Initially, this reentrant vi creates its own queue. Should I give to this queue name? What will happen if this vi reproduces several times? They will share the same queue (by name) or they will create new ones?

  Thank you

  It is always better to manage the names of queues where you need to retrieve the queue reference elsewhere in your code. For a reentrant VI spawning queues, the usual way to do this is through the property node "name of the VI. If the VI is reentrant, the name VI string contains the number of the clone and this one is unique

  Kind regards

• initialize the queue

  I'm working on a state machine in queue configuration. I use a def type with all of my States possible in what elements of my queue. At the beginning of my program of the queue must initialize with a specific order, as shown in the snippet below. However, when I run the code and probe the queue at the end, I end up with 0 entries in my queue. Am I missing something? This is my first time with queues in labview.

  

  If you look at the queue on the wire that is a reference to the queue and not the queue itself.

  To test the use of the Get queue status VI application and probe them elements # in the queue output.

• Writing in the spreadsheet with the queue

  Hello

  I am a beginner with queues and I have a few questions.  I have attached a simple example of code that I wrote to better implement a consumer who can queue data and write on a worksheet after running the code.

  First of all, I noticed that the queue still has residual remaining after the code ends.  It then writes this element to the file to run the vi.  I can't figure how to get rid of this element.

  Second, anyone have any suggestions to improve this code?  I've been playing with it for quite some time and I finally got to work like that, but it is certainly configured differently from the other examples I've seen.

  Thirdly, I am reading the number of items in the queue, but the two in the loop of the producer and the consumer, told me that there is no element.  How can this be?  My output file seems to work and I certainly put items in the queue.

  Finally, in the future I'll use data from the queue in two places.  Here I've implemented a notifier to do the job.  This is the best method?

  Thanks for your help!

  Jason

  The reason why you do not get the last element of the queue (at least not until you restart the VI) is that you have your automatic indexation tunnel that collects all the data to send to the writing on file SS service cable for moving to register.  So this last piece of data from the queue to get into the shift register, but it is not getting into the 2-D chart by the tunnel of automatic indexing up to the next iteration of the loop.  When you rerun the VI, as the shift register is not initialized, it is already there and became the first point of your next data execution.

  Why did you put the register shift in?  Just remove and just use the tunnel of automatic indexation.

  I don't know what you really want to do with the 2nd loop to say if the Notifier is correct or not.  But if you do not want to lose data in the other loop, then you need to use a second queue and have your producer loop enqueue data in the two queues, a queue for each consumer loop.

  With regard to the elements draws in the queue, seeing how your code is configured, the queue will almost always empty because the dequeue function will be ready to pull out the element immediately after the enqueue function puts in.  Unless you have your loop producer much faster than your consumer loop running, you will not see a build up of the elements.  (Try putting an expectation of more of 100 msec in your loop of consumer.  Then you will see elements accumulate in the queue.)

  I don't know why you put the spreadsheet feature writing after the loop.  Normal use for queues in an architecture of producer/consumer must transmit the data to a separate loop that contains the functions write file.  This way he can work at his own pace, but write the data and make sure that you do not lose it.  As you have now, if your code runs a long time, you may run out of memory when at the tunnel of automatic indexing table becomes too large.  And if your application crashes before you complete it with your stop button, then all data are lost because you did not it writes the file.

• number of items in the queue

  I'm working on an upcoming project that will need to use a loop of producer/consumer structure. Right now, I have added a simple test of how I want the VI to work, but I'm having a problem. When I run the VI, the "elements of # in the queue" increases ever from time to time. I used the Undo button to stop execution when the consumer is in an infinite loop (which I know is bad). I'm trying to ensure that all items are consumed and stored in my database.

  Anyone know what is happening with the VI?

  Thank you

  Eric

  
  

• Photosmart C5180 - impossible to remove from the queue of the printer

  Hello

  I am trying to print something, but I can't delete the first document in the queue (what's more, I want to print). It is frozen on the "remove" status, but nothing happens. I tried restarting both the printer and laptop, but still nothing. Help!

  In addition, the State of the printer on my laptop says ' paper' (but not on my printer) and yet it is not paper. Any help very welcome!

  Hello

  This can help with the paper stuck in the print queue.

  In Control Panel, open administrative tools and select abuse.  Scroll down to the print spooler service, right click and select Properties, then click the Stop button.  Now search for C:\Windows\System32\Spool\PRINTERS, then delete the work inside this folder - you may need to click a command prompt to get the authority to open the PRINTERS folder.

  Restart the computer and you should find that the document has been removed from the queue.

  Kind regards

  DP - K

• Sequential simultaneous writing of the queue

  Hello everyone, nice day.

  I have what should be a very simple matter.

  I'm currently implemented a producer consumer-consumption-consumer architecture. (Loop acquisition > write disk acquisition > read data from disk data > display of the user based on the data.) In plain language, I have a created the data loop, a loop of these data, a loop of disc storage and a loop displays a user interface. (This isn't supposed to be a real-time application, and I am aware of the charge created by the writing and the reading of the disc). Just stick with me on this one.

  So my problem occurs concerning the second loop. This loop is responsible to write the data be queued (produced in the loop 'Acquisition') on the disk. The problem is also, feeds on a queue to the loop of "reading disc". This configuration causes a few obstacles. The main obstacle arising from the nature of queues of LabVIEW. The loop "write to disk" writes only a part of the queue of the 'Acquisition' at the same time. This general is not really a problem, until you consider that this loop also determines the execution of the loop of "reading disc", with the use of queues. As a result, this loop determines the rate of the next loop and was therefore likely to slow demand and leave a large number of items in the queue. In addition, you must keep in mind, I'm only queueing about 7 MB of data per element, and my HARD drive has a write speed average of 60 MB with a 64 MB cache. Therefore, my installation I can only write one item at a time, therefore making me use only 7 / 60MB of bandwidth from my drive.

  My question is; It be possible to have the loop "write to disk" write several items in the queue at the same time. I hope that I can write simultaneously enough items that I can use my bandwidth 60MO together writing and speed up execution of any sub routines that depend on data written to disk.

  I know there is probably best architecture for this application, but for the moment, I am limited to this architecture. If you have any suggestions for other architectures, I'm more willing to listen to, but coming back I am looking for a way to improvise simultaneous tail reads and then write them to disk with my current structure.

  Thank you all, thank you for the help.
  Taylor S. Amarel
  Learning is alive.

  You can put your element Dequeue function in a loop For and set N to a number so that you get several items from the queue at a given time.  Turn on indexing and you will have a table of data.  Write the table in its entirety on the disc.  This should speed things up a bit.  Don't forget to use shift registers for the sons of the error and the reference to the queue in the loop For and also put a little delay in the loop to stop 100 percent CPU usage.