Producer/customer architecture sync

I built a producer/customer architecture type code and I ran into the problem that if the producer loops ends normally [because it produced the specified amount of data], it kills the queue as well so the consumer loop cannot output the data which is still in queue because the queue is destroyed - data is lost.
How is it possible to syncronise the two loops, how can I make the VI wait until the consumer empties the queue?
Thanks,
Krivan

Just out of curiosity:
as seen in the attached picture I moved the release queue VI from the producer loop to the consumer loop. This way I wanted to ensure that the queue is only released if the queue is empty. Now this implementation works according to the tests I have made so far and I don't use notifiers and the error handling is much easier.
Are there any drawbacks of my implementation? (Because in Felix's nugget various issues have been mentioned)
Attachments:
consumer.PNG ‏25 KB

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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

Producer/Consumer Architecture

Hello All,
I am currently working on an application using State Machine Architecture where I have to monitor various parameters (7 temperature values & 3 pressure values), along with this I have to On/Off a Clutch using a digital Output for set time (e.g. On for "X" seconds OFF for "Y" seconds), but as soon as the pressure and temperature values go beyond upper or lower limits or whenever the user presses the Emergency Stop (that means I have to monitor Digital Input as well) so I am moving to different error cases depending on which values go beyond limits or emregency pressed etc..
But this realisation is not working fine as I have to monitor and control several other things in addition to acquiring data....till now I just have used State Machine Architecture, I have seen Producer/Consumer Template but not quite sure how to realise such kind of application which involves data acquisition along with user interaction and monitoring.
Could someone please put some light on giving similar kind of example or what else I can try with this problem.
Regards
James

Hello James,
A Producer/Consumer architecture will certainly do the trick for you. I am sending you an example that has the Data Acquisition section in the producer loop. However, you can also put your User Interface in the Producer loop and have the Data Acquisition in the Consumer loop. The Queues are used for sending data from the Producer to the Consumer(s) loop(s) (you can have multiple comsumer loops).
You will just have to design specific cases to react to different user inputs.
By the way, this example is from LabVIEW Basics II training course. If you have never taken LabVIEW Basics I and II, I highly recommend them. You can self-pace the class or take it with an instructor.
LabVIEW Courses
Hope this helps!
Message Edited by Kalin T on 03-23-2007 09:57 AM
Kalin T.
National Instruments
Attachments:
ImplementedProducerConsumer.zip ‏250 KB

External reporting tool (Cognos) to produce customized reports from BPM 5.7

Can I use external reporting tool (Cognos) to produce customized reports from BPM 5.7? Is it possible to query BPM DB for historical data (not BAM dashboard)?

Hi Steve,
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Hi all,
I am using a Producer - consumer architecture for my data acquistion as in the belwo diagram.. at some time i am stuck insde the while loop continously acquiring data .. is there any way i use one stop button as a functional gloabl variable and stop inside (consumer while loop) as well as producer architecture....
Why i need this ?? so many design rules say that global variables are not a good idea...
Thanks in advance...

FGVs will work fine for your application. You can also wire your error cluster to your stop button. Your producer loop should throw an error 1 when the stop button is pressed, which will in turn stop your consumer loop. But you would need a slightly different design for this. Your consumer loop is designed to not advance until the stop button is pressed. Instead of using and enum, you can use your producer loop to control the trigger to take a measurement. No need for the while loop in the consumer loop this way. You could set up your consumer loop to take a number of measurements, and then quit or take measurements for a certain amount of time. Either way, you can stop your while loop when it times out.
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Hello.
I have some question about producer consumer pattern.
People say that consumer shound NOT add elements into producer queue. Lets say that some states in in consumer need to stay active for eg 5 minutes. We also should be able to pause/resume state execution and exit program in any time.
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Attachments:
testRemoteLogging.zip ‏124 KB

VI server
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State machine VS producer consumer architecture - Time Analysis

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[ LabView professional Development System - Version 11.0 - 32-bit ]
LabView Gear:
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2. The Imaging Source USB 3.0 monochrome camera with trigger : DMK 23UM021
OPERATING SYSTEM - [ MS windows 7 Home Premium 64-bit SP-1 ]
CPU - [Intel Core i7-2600 CPU @ 3.40Ghz ]
MEMORY - [ 16.0 GB RAM ]
GPU - [ NVIDIA GeForce GT 530 ]

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Abhilash S Nair
Research Assistant @ Photonic Devices and Systems lab
[ LabView professional Development System - Version 11.0 - 32-bit ]
LabView Gear:
1. NI PXI-7951R & NI 5761
2. The Imaging Source USB 3.0 monochrome camera with trigger : DMK 23UM021
OPERATING SYSTEM - [ MS windows 7 Home Premium 64-bit SP-1 ]
CPU - [Intel Core i7-2600 CPU @ 3.40Ghz ]
MEMORY - [ 16.0 GB RAM ]
GPU - [ NVIDIA GeForce GT 530 ]
Attachments:
Control 1.ctl ‏6 KB
Control 2.ctl ‏6 KB
Motor-UNI_Directiona Dev 3-TIME_ANALYSIS-2.vi ‏54 KB

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I am trying to devolope Producer/Consumer program to communicate with MS SQL database.
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vasicekv wrote:
Thank you Jim, it really helps me!
Do you also know any other library to communicate with database in labview which is reentrant?
I mean I am focused on speed my labview-databse communcation up.
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knapkerd wrote:
I am trying to aquire two separate tasks (one with analog and one with digital signals). The digital signal needs to be aquired at a much higher rate (10 times higher). The data from both of these aquisitions is required for writing to the same file and doing calculations. I was wondering if it is possible to use 2 Producer loops and 1 Consumer loop? I would need to use an enqueue in each producer loop and then dequeue them both in the consumer loop. Will this work?
Thanks.
--Robert
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Do you want to do this with 2 different queues? If so, you may need to put some timeout functions on your dequeue functions in your consumer loop otherwise it will only run as fast as it gets the data from the slower queue.
Message Edited by Ravens Fan on 05-07-2008 11:38 PM

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Producer/customer architecture sync

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