Releasing Queue in Producer Consumer model

I am having a VI which reads data from ethernet,writes to disk,processes and displays. Since lot of processing and displays are there, I am converting it to a Producer- Consumer model so that no data is lost.
I am using 2 loops. IN the Producer I am doing the UDP read and Write to disk functions.and use the enqueing also.In the Consumer loop I am dequeing it and do all the processing and displays.My idea is to avoid any data loss in UDP reception and file writing.
My confusion- where to use the release queue?from the Producer or Consumer ? In a third loop ? Should it be in a sequence structure ?
How to set the loops stop conditions ?
My requirements for stopping - when I press the stop button the program should stop completely(the Consumer loop should stop only after dequeing and processing all the data in the queue). If i don't press the stop button the whole program should run continuously (if data does not arrive for some time it should wait without time out-i am using -1 for the time out condition in UDP read.)

Here is the ultimate Producer-Consumer loop. It queues a stop command when the stop button is pressed. This ensures that every element is dequeued and processed before the bottom loop stops. The last queue data to get processed is the stop command because after you press the stop button, the top loop stops enqueueing more elements.
If your data type is other than a string, you can create something to represent stop, like NaN for a numeric.
Notice the shift registers. This is good practice. Every loop starts with an error out of the previous loop. If an error occurs, it is passed on to the next loop iteration. Also, if an error occurs in the consumer loop, the loop stops. It is good practice to put shift registers on the queue reference also, but not necessary in this case. If you use a For loop, and the loop iterates 0 times, the output of the queue reference would be a null reference, and the Release Queue would not release the queue. With While loops, they always iterate at least once, so it isn't necessary. Its just good practice to make a habit of using shift registers so you don't forget when using For loops.
Notice also that the error in to the Release Queue is not wired. If there were an error, the Release would not take place. All errors are merged at the end to report exactly where an error occured. A timeout is included in case an error prevents the stop command from being enqueued or dequeued.
- tbob
Inventor of the WORM Global
Attachments:
ProducerConsumer.vi ‏53 KB

Similar Messages

Could Buffer replace the Queue in Producer/Consumer Design Pattern

Hello,
I have a question that the task of Buffer is to store the data and the queue is also of the same so could we use the Buffer inplace of queue in a Producer/Consumer Design Pattern.
Solved!
Go to Solution.

No, those buffer examples are not nearly equal to a queue and will never ever "replace" queues in producer/consumer.
The most important advantage of queues for producer/consumer (which none of the other buffer mechanics share) is that it works eventbased to notify the reader that data is available. So if you would simply replace the queue by overly elaborate buffer mechanics as you attached to your last post, you will lose a great deal of the the purpose using producer/consumer.
So, to compare both mechanics:
- Queue works eventbased, whereas the buffer example does not.
- Queue has to allocate memory during runtime if more elements are written to the queue than dequeued. This is also true for the buffer (it has to be resized).
- Since the buffer is effectively simply an array with overhead, memory management is getting slow and messy with increasing memory fragmentation. Queues perform way better here (but have their limits there too).
- The overhead for the buffer (array handling) has to be implemented manually. Queue functions encapsulate all necessary functionality you will ever need. So queues do have a simple API, whereas the buffer has not.
- Since the buffer is simply an array, you will have a hard time sharing the content in two parallel running loops. You will need to either implement additional overhead using data value references to manage the buffer or waste lots of memory by using mechanics like variables. In addition to wasting memory, you will presumably run into race conditions so do not even think about this.
So this leads to four '+' for the queue and only one point where "buffer" equals the queue.
i hope, this clears things up a bit.
Norbert
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

Can anyone tell me what's wrong with my queue or producer consumer loop?

A Labview engineer helped me with the overall structure of my program, necessitated by the fast data sample rate and post processing requirements. He recommended the producer/consumer loop and using one of the example files (Cont Acq graph voltage - int clk) to do the actual data acquistion. So I put together the loop and go my two channels of data acq going in the producer loop. However, nothing's getting picked up in the consumer loop and none of my data gets displayed over there.
Anyone care to take a look at it and let me know what I'm doing wrong?
Solved!
Go to Solution.
Attachments:
P-C Yanmar Program.vi ‏296 KB

Your Enque Element should be inside the while loop where you aquire the data. As it is now, the data has to stop being aquired before you send the last set of aquired data.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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Basic Producer/Consumer loops for a newbie

Labview neewbie here.
I was looking at Producer Consumer loops.
Can anybody give me a very basic explanation of how to set one up.
I want to take readings from a HP 53131A counter and store them in an excel spreadsheet.
I understand the part about labview slowing down as it opens the Excel file, and a seperate loop will help solve this.
But I dont understad how to set up the Que function.
Thanks.

Multithreading will not make excell open faster but using concurrency you can have more than one operation operate ate different speeds. The nice thing about the produce consumer model is that the if the consumer is slow or unreliable (freeses up) the producer doesnt care and will continue. To use a queue is very simple, 1. create the queue, name it(optional) and give it a data type (ie int, array of floats ...) in the produce loop use the enqueue vi to add items as needed to the queue, in the consumer dequeue these items (using a timeout = -1 the loop will wait for a new item and not consume resources) the consumer can process the data acquired in the producer loop.
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

Running one sub vi in background while the main vi uses it's generated data, producer/consumer?

Hi,
I would like to have a subrutine running at the same time as the rest of the main vi. The subrutine will be constantly producing data, and the main rutine should do different tasks depending on which data has generated the subrutine in that instant. I have read about producer/consumer design http://zone.ni.com/devzone/cda/tut/p/id/3023 but I don't know how to implement this with LV 5.1 Somebody know if it's possible, or there is something missing in my old LV version? The name of the sub vi about queues mentioned in the link are different than the one I have, and I don't achieve to connect correctly the ones I have... (that are create queue, destroy queue, insert element queue and remove element queue).
Or, does anybody know other way to do what i want?
Please, some help..
Thanks a lot.

Hi javivi,
The queues in 5.1 are capable of supporting the producer-consumer model. See the queue example under "Execution Control Examples". It's showing a simple string value being "inserted" and "removed". To insert non-string data-types, use "Flatten to String" before "Insert Queue Element" then "Unflatten from String" after "Remove Queue Element".
What "different tasks" will you do based on the data? How is the data being read by the program - are you reading an analog-input? Is it a "continuous" acquisition?
Cheers!
"Inside every large program is a small program struggling to get out." (attributed to Tony Hoare)

What is the Fastest producer consumer method. Queue, RT-FIFO, Event

Hi all,
Another curly question for the pro's:
I have recently inherited some labview code that uses RT-FIFO for the transfer mechanism in the producer consumer architecture.
The code was first written 3-4 years ago and is presently in LV8.6. It is possible that the reasons for the architectural decision no longer exists.
I am skilled using a queued producer consumer architecure,
I understand the RT-FIFO Architecture.
I have begun using a user Event Based architecture.
(I have attached samples of each)
I also see the existance of a priority Queue
Each method has it's own capabilities and deficiencies, That aside, does anyone know the relative performance of each method.
(Assuming single process)
I would expect RT-FIFO to be fastest, it appears to be a low feature version of a standard queue.
What is the perfornace hit for using a more coding freindly Queue
The RT-FIFO description speaks of commications between time critical and lower priority threads.
Until today, I believed that Queues had the same capability.
I have included an event method I commonly use for peer review and to help to fellow users..
It allows:
1. Multiple producers with different data types
2. Processes repecting order of production.
3. Allows for asynchronus checking of functional notifiers such as stop, start and abort.
4. In a non real time system it can include front panel interactions.
What I don't understand about it is what overheads, or thread priority changes that may be experienced by using this architecture (it solves a lot of problems for me).
Thanks in advance,
iTm - Senior Systems Engineer
uses: LABVIEW 2012 SP1 x86 on Windows 7 x64. cFP, cRIO, PXI-RT
Solved!
Go to Solution.

Are you running into a situation where the difference in time between producing an event, and consuming it, is actually causing your problems? If not, this is not a question worth worrying about. Use whatever is most appropriate for your application.
There's no need to make wild guesses - build a VI, benchmark and test! The attached is a reasonable starting point, although I think the event structure may be slow due to setup time but may respond quickly once running. If you experiment with this, you'll probably find that there's no definite answer to which is fastest. Changing the size of the RT-FIFO, or of the queue, makes a big difference in speed. At least in my testing, a single-element RT-FIFO is fastest, but an infinitely large queue is faster than a small queue, and a longer RT-FIFO is much slower than the single-element version.
It's important to realize that RT is not another word for Fast or Efficient, it's another word for Consistent. For the purposes of real-time (deterministic) execution, it doesn't matter how fast the RT-FIFO functions are so long as they execute in exactly the same amount of time, every time (with the exception of a "forever" timeout value, of course). You can use either a standard queue or an RT-FIFO to communicate between loops. One use for an RT-FIFO is when a time-critical loop is enqueuing the data. It guarantees that the amount of time needed to put data into the FIFO will not vary. Enqueueing data in a standard queue will sometimes be faster than other times, depending on whether there is already space available in the queue or space needs to be allocated for the new element. If this variation is unacceptable, then use an RT-FIFO; otherwise, the standard queue works just as well.
If the architecture shown in your image is working for you, I don't see any reason to change it.
EDIT: oops, almost forgot to attach the code I used for testing!
Attachments:
Event vs Queue.vi ‏21 KB

Stopping producer consumer loop at the same time

In my application I am using producer consumer architecture. In the producer loop, I am acquiring data, processing and outputting the result (feedback control system). Also in the same producer loop I am inputting all the data to a queue and then in the consumer loop I am writing data to a file. I have a stop control on the front panel and error from the queue and error from the data acquisition all wired to OR gate to stop the while loop. ( I attached the picture of the code). Whenever I press stop form the front panel program wont completely stop. I think it is because consumer loop still running. Is there way to stop the both loops at the same time. I tried creating local variable but it slows the program. Front panel stop control mechanical action is set to switch when released.
Attachments:
app.PNG ‏262 KB

In the consumer loop you should check the error after the Read Queue function.
TOn
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Unsynchronized Producer Consumer Problem

Hi I would like some help implementing an unsynchronized producer consumer with an unbounded queue (implemented using an ArrayList) I have both the producer and consumer sleeping for random amount of time (producer wakes up faster). The problem is that sometimes the producer never gives the consumer a chance to run.
Note I have a notify after I add stuff to the ArrayList. I dont know whether its my choice of collection object or the fact that I have not defined a wait for the producer.
I don't know whether I have explained my problem clearly so feel free to ask some questions. Thanks

Maybe I should not have used the word unsynchronized.
But what I am trying to do is have the producer
putting more objects into the buffer than the
consumer can remove. The problem is that my producer
does not let the consumer run ever.The basic model is like this:
// Producer
while (!done()) {
synchronized(queue) {
    while (queue.isFull()) {
      queue.notifyAll();
      queue.wait();
    queue.put(next job);
    queue.notifyAll():
// Consmer
while (!done()) {
synchronized(queue) {
    while (queue.isEmpty()) {
      queue.notifyAll();
      queue.wait();
    job = queue.get();
    queue.notifyAll():
    process job
}I expect I've missed a subtlety or two in the whole get/put/wait/notify cycle--I always have to reconstruct it from scratch in my head, it's not something I carry around. It should be pretty close though and should show you the main pieces.
As mentioned, if you use the concurrency package, some of that gunk is hidden from you.

Progmatically stop vi with producer/consumer architecture

I can't seem to get my VI to fully stop, so that I can go on to do some more things in the program. I am trying to progmatically stop the vi (pictured below), so that I can return to my main gui (not pictured). The main gui just consists of a login, exit test system, and run test. Once the user presses run test, the vi pictured below opens.
I am using a producer/consumer architecture with a state machine. The problem I run into is that when I press the "Main Menu" button, it should close the pictured vi and return to the main gui. I tried using the vi server, and when the user presses the Main Menu button, it fires an event and then it goes to the Stop state in the consumer loop, which opens a reference to the vi's (one for the strip chart vi and another for the gage vi), closes the front panel using an invoke node and then closing the reference. I also tried adding in the abort vi method after the close front panel and it still gave me the same result.
Here is the catch, it does close the vi's, but it does not stop the while loops (producer and consumer), or it stops only one of the loops. I thought of putting in a constant in the event structure for when the Main Menu event is fired, but that will stop the producer loop before the consumer loop reveices the info to go to the stop state, so the consumer loop does not end.
I also tried a "dummy" control that was connected to the comsumer loop Stop terminal (for the while loop), and then progmatically changed the value in the stop case to true and then read that value in the producer loop to, hopefully, stop both loops, but it did not work either.
I am sure that it is something so stuipidly simple that I cant see it right now
Kenny
Kenny
Attachments:
test system.gif ‏252 KB

Hi Kenny,
I think of two solutions to your problem. First, use the message queue to pass the message "stop" or something from producer to consumer or second (and I think, better), use occurrences. I made a little draft how it could work.
You have to pass the occurence- Refnum to both VIs, the producer and the consumer, when the producer finishes execution, then use "Set Occurence".
In the consumer blockdiagram you react on the generated occurrence.
If you set in the VI- properties "Open Frontpanel when called" and "Close if originally..." the VI Frontpanel should disappear itself when execution is stopped.
Hope this helps,
Dave
Message Edited by daveTW on 08-14-2006 04:53 PM
Greets, Dave
Attachments:
occurrence 1.png ‏1 KB
occurrence 2.png ‏5 KB

How to change the transmission rate of data flow in producer/ consumer pattern

Hi All
I am new to labview and trying to design a application to transfer image data in different rates, that means I can change the transfer rate in the transmission process. In fact,I refer to the the Queue Basic.vi to achieve this function by Changing the delay value of dequeue and enqueue.The program is divided into three parts:
The first part is the sender in vc used to split and send image data.Data size is 226kb and each time we send a 1kb packet;
The second is labview rate-change part，use producer/ consumer pattern and queue to transfer data;
The third one is the receiver in vc,receive data in sequence and synthetic images.
The entire transfer process is: image data was sent from the sender to producer loop through DLL, then enqueue--dequeue in consumer loop--DLL--receiver.The sleep time in vc sender is equal to the delay value in producer loop and this makes it look like the data generated as in the loop.
Now this is where my dilemma is：
When transferring data, if the producer loop and consumer loop delay value are equal(both 20ms), I can see image synthesis at a constant speed and no data lose; if I change the consumer loop delay value and make it greater than the producer delay(one is still 20ms and another is 50ms),that means receive in a lower rate and store data in queue. I can see Elements in Queue
increase but the image data randomly lost, and the image synthesis speed is not reduced.
My question is why image data loss and I can't see the image synthesis speed reduced when change the delay value in consumer loop?
Do anyone know how to solve the problem? Are there any examples I can refer to? Any suggestions are greatly appreciated!
Attachments:
image1.JPG ‏56 KB

thisoldman,
I don't have '/usr/lib/modules/3.17.3-1-ARCH/build/Documentation/VGA-softcursor.txt' on my file system. Does it contain the info about changing the blinking speed?
P.S. The other two links I found yet before starting this thread. I only found in them the recommendations about changing "the color and shape of the cursor and turning blinking on/off" (as I mentioned in the original question). Did I miss the info about the blinking speed?
PPS: I found the vga-softcursor.txt here: https://www.kernel.org/doc/Documentatio … cursor.txt
But that file doesn't tell about changing the blink rate either.
Last edited by nbd (2014-11-23 20:55:41)

Producer consumer timing

Back again
Thought I was getting somewhere now I am at another brick wall.
Bit of background:
I have a producer consumer set up. In the producer loop there are 2 DAQmx read VI's reading from a Pressure task and a Temperature task. These are multiple channels, 1 sample, outputtng a 1D wave form. This loop is set to run every 20ms. The two tasks were created using DAQmx Create Channel VI's and DAQmx Start Task VI's. The producer loop feeds a display on the front panel with the sensor values and this hopefully is refreshed at the 50Hz I have asked for. Secondly the loop bundles up the waveforms and puts them in a queue where they are picked up for logging by the consumer loop. In the consumer loop I have a wait 1000ms timer and a Write to Measurment File Express VI to do the logging. This is supposed to log at 1 per second.
The queue is set to enqueue at opposite end, and the max queue length is set to 1. I.E. I only want to log the value at that specific second, but I want to show the data on the front panel at 50 times a second.
Now heres my problems:
1) I replaced the DAQmx Create channel's with a MAX project task wired into my DAQmx Start Task VI. As expected the thing picks up and displays the sensor values as it did before. However there is now a problem logging. Before when I had the DAQmx Create Channel, the logging recorded my values correctly at 1 second intervals. The time stamp in the X column went up by 1 second for each set of results. But now, with the MAX project task (needed because of custom scales and differing min/max values for different sensors), The logging still seems to happen at 1 per second, but the time stamp intervals are the same as the sampling rate set in the task!!! (ie at 50Hz the time stamp goes up 20ms for each result even though the results are being recorded at 1 per second)
2) The timing just seems out of whack.
I keep getting errors that the requested data no longer exists, that it was there but then was over written. Increasing the buffer size or sampling rate is supposed to remedy this... but what sampling rate? the rate set in the task? or the loop iteration speed? I dont understand.
Secondly, despite telling my consumer loop to wait one second between picking up stuff out of the queue to log, it seems to be going round nearly the same pace as the producer loop. To top this off the producer isnt going round at the speed I asked it too either! I put indicators on the loop counters to see this. they are going round at maybe 2Hz.
I have included my VI's
What am I doing wrong, its really bugging the crap out of me!
Attachments:
EngineMon.zip ‏90 KB

The reason you would use get time and date in seconds to to ensure that you log every second. If you use the 1 second wait then you do not take into account the exicution time of your loop. If you add more to the loop in the future than you will see that you do not log every second as you thought. If you loop took 500ms to exicute and you have the 1000ms wait then the actual excution time for recoding to file is 1.5 seconds not 1000ms as you desired. The way I did it will always give you one second unless you exicution time for your loop exceeds one second.''
I did make one change to the vi. I shoulod have put the write in the true false case so that the write only happens when the 1 second has expired.
Tim
Johnson Controls
Holland Michigan
Attachments:
VDU3.vi ‏59 KB

Time Stamps in Producer/Consumer Setup

I am trying to acquire signal from a Gas Analyzer, Flow Meter, and 3 RTDs. My hardware is a NI 9215 and NI 9217. I need to write the data to a file with a time stamp at which the sample was read. The program is written in a producer/consumer setup in which the data is being acquired in the prodcuer loop and sent to the consumer loop to be written. I can get the samples written to the file okay. However, I have not figured out how to put the time stamp in the data file correctly. I thought the time stamp was created with the corressponding measurement at the Data Acquisition VI. However, whenever I open the data file, there are only 0s in the time column. So, I've tried to use Format/Date String to add the time stamp. I can get it to work if I place it in the consumer loop. However, the time stamp is not accurate. It puts the same time stamp up to six digits of precision for two consecutive samples. I've tried to figure out how to add it to the producer loop, but I don't know how to add it and the measurements to the queue at the same time. Please tell me the best way to acquire signals with the exact time stamp and write them to a file using a producer/consumer design.
Example:
Date             Time       RTD1 RTD2      RTD3   CO2    Flow
5/26/07      5:20:01.25       57         56         56.5      100       0.5
5/26/07      5:20:01.30       57         56         56.5      100       0.5
5/26/07      5:20:01.35       57         56         56.5      100       0.5
Attachments:
Producer-Consumer From Scratch2.vi ‏75 KB

Okay, I've put it in a For Loop and it will connect now. However, whenever it runs the time stamp increments for a couple seconds and then it just repeats. How do I correct this?
Attachments:
Producer-Consumer From Scratch2.vi ‏88 KB
pleasework.txt ‏20 KB

Input and output on same device, producer/consumer structure

Hello interested people,
I have a question about using the same device for both digital inputs
and outputs. I have written a simple program of one while loop
that continuously polls the device, processes, and requests. I
have addressed the device using two DAQmx Asst. and I have attached
them with their error in/out cluster terminals to provide data flow and
eliminate the chance of addressing the devices at the same time (which
produces an error). Now I want to change this program structure
to a producer/consumer loop foundation with state machine.
In this design, I will have the DI in the producer loop and the DO in
the consumer loop, under one of the states. I can't simply
connect the error in/out ports in this configuration, so my question is
how to avoid the error caused by addressing the same device
simultaneously with two different tasks (input and output)? I
have attached two VI's, the "One Loop" vi is the original configuration
(simplified), and the Producer-Consumer vi is a NONSENSICAL program
that simply represents the desired configuration. (I don't need
any comments on the programming of this vi, it is only an example for
illustration of the problem).
I am thinking about bundling the input data and the error cluster, both
from the PXI 6528 DI, into one cluster, queueing that up, and
unbundling the de-queued elements for some kind of data flow between
the producer loop and the "Request" state of the consumer loop.
Is this the right approach, or am I barking up the wrong tree?
Thanks
Attachments:
One Loop DO DI.vi ‏102 KB
Producer-Consumer DI-DO.vi ‏106 KB

Hello,
It sounds to me like you really have two modes:
1. user interface actions determine execution
2. user interface is locked, and execution is automated.
I think it would make sense to use the producer consumer for an architecture. Basically you would do the following:
1. program the producer to handle the user interface as you normally would.
2. provide one additional event case in the producer which would be your "automated handling" case. In that case, you could put a state machine which could run until whatever conditions were met to put your program back in "user interface mode".
Keep in mind that you can use custom USER EVENTS to programmatically generate events ie. you can trigger the start of your "automated handling" form anywhere in your code at virtually any time.
I think this would allow you to take advantage of the producer consumer architecture in its intended spirit, while integrating an automated routine.
I hope this helps!
Best Regards,
JLS
Best,
JLS
Sixclear

Running subVI in parallel with itself using producer-consumer pattern

I'm using the procuder-consumer pattern to create what I call threads in response to various events much like in Producer Consumer with Event Structure and Queues
I have several physical instruments, and would like to run the exact
same test in parallel on each of the instruments. I have a subVI
that takes as inputs a VISA resource and a few control references among
other things and then performs the desired experiment. I have a
separate consumer loop for each physical instrument, with this subVI
inside each consumer loop.
My test VI worked great; each consumer loop was a simple while loop
incrementing a numeric indicator (not using my real subVI above).
However, my real program can only run one consumer loop at a time much
to my dismay. Reworking my simple test VI to use a subVI to
increment the indicator rather than just explicitly coding everything
resulted in the same problem: only a single consumer loop ran at a time
(and as I stopped the running loop, another would get a chance to
begin). The subVI in this case was extremely
simple taking only a ref to the indicator and a ref to a boolean to
stop, and incrementing the indicator in a while-loop.
Is there a way around this? Now that I've spent the time making a
nice subVI to do the entire experiment on on the physical instrument, I
thought it would be fairly trivial to extend this to control multiple
instruments performing the same experiment in parallel. It seems
only one instance of a given subVI may run at one time. Is this
true? If it is indeed true, what other options do I have? I
have little desire to recode my subVI to manually handle multiple
physical instruments; this would also result in a loss of functionality
as all parallel experiments would run more or less in lock step without
much more complexity.
Thank you.

You need to make your subvi reentrant. Then it can run several instances at any time with each instance occupying its own unique memory space. Click on File - VI Properties - Execution, and check the reentry execution checkbox. Then save the vi.
- tbob
Inventor of the WORM Global

Producer/Consumer Design Pattern with Classes

I'm starting a new project which involves acquiring data from various pieces of equipment using a GPIB port. I thought this would be a good time to start using Classes. I created a GPIB class which contains member data of: Address, Open State, Error; with member vis such as Set Address, Get Address, Open, Close...general actions that all GPIB devices need to do. I then created a child class for a specific instrument (Agilent N1912 Power Meter for this example) which inherits from the GPIB class but also adds member data such as Channel A power and Channel B power and the associated Member Functions to obtain the data from the hardware. This went fine and I created a Test vi for verfication utilizing a typical Event Structure architecture.
However, in other applications (without classes) I typically use the Producer/Consumer Design Pattern with Event Structure so that the main loop is not delayed by any hardware interaction. My queue data is a cluster of an "action" enum and a variant to pass data. Is it OK to use this pattern with classes? I created a vi and it works fine and attached is a png (of 1 case) of it.
Are there any problems doing it this way?
Jason

JTerosky wrote:
I'm starting a new project which involves acquiring data from various pieces of equipment using a GPIB port. I thought this would be a good time to start using Classes. I created a GPIB class which contains member data of: Address, Open State, Error; with member vis such as Set Address, Get Address, Open, Close...general actions that all GPIB devices need to do. I then created a child class for a specific instrument (Agilent N1912 Power Meter for this example) which inherits from the GPIB class but also adds member data such as Channel A power and Channel B power and the associated Member Functions to obtain the data from the hardware. This went fine and I created a Test vi for verfication utilizing a typical Event Structure architecture.
However, in other applications (without classes) I typically use the Producer/Consumer Design Pattern with Event Structure so that the main loop is not delayed by any hardware interaction. My queue data is a cluster of an "action" enum and a variant to pass data. Is it OK to use this pattern with classes? I created a vi and it works fine and attached is a png (of 1 case) of it.
Are there any problems doing it this way?
Including the error cluster as part of the private data is something I have never seen done and ... well I'll have to think about that one.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Releasing Queue in Producer Consumer model

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