I need tips about queued message handler

[smilegv]

Hello, I have to use, for the first time a queued message handler. I'd like to know what is the best way to share data between cases in a loop and from a loop to another, I think with local variables  isn't  the best way...

However all the tips on the queued message handler are welcome!!!

Thanks

[Norbert_B]

As "Queued Message Handler" is a name used for slightly different implementations, can you please provide a small example of your code?

Depending on the "sharing" of data, you can internally use a shift register for one QMH.

Distribution of data to other QMHs, you would use the queue of the target QMH. The target QMH has to inlcude a case storing that data in e.g. a shift register.

Norbert

[crossrulz]

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@smilegv wrote:

I'd like to know what is the best way to share data between cases in a loop

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Shift registers.  Doesn't matter if QMH, State Machine, Producer-Consumer, etc.

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@smilegv wrote:

I'd like to know what is the best way to share data ...from a loop to another

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Well, now that completely depends on what you are passing around.  Streaming data?  Use a Queue or User Event.  Last known value (ie Tag)?  Global Variables, Action Engine.

[Bob_Schor]

In "recent LabVIEW Versions" (LabVIEW 2012 and more recent, possibly earlier as well), you can open a new Project, choose "From Template", and choose Queued Message Handler.  It will create an NI-Standard Queued Message Handler with comments, documentation, and suggestions on how to modify it for your own needs.  It includes passing data between States on shift registers, and passing data betwen loops (the QMH and an Event Loop) using Queues.  By studying this, making some modifcations and "trying it out", you should be able to figure out a lot about this Design Pattern.

Bob Schor

[drjdpowell]

Also have a look at the JKI "Statemachine" template (which is actually a type of queued mesage/event handler).  Uses shift registers.

[Yamaeda]

Sending the data tobthe message handler is done with the queue, sending it back, which should rarely be needed, can be events.
/Y