Message Pumps in DQMH

[joerg.hampel]

On a first - quick - glance, I can't see anything wrong with your block diagram. Maybe the problem lies outside your captured part? Which events are you triggering, what does the helper loop do, ...?

If you want, we can do a quick TeamViewer (or similar) session tomorrow in the morning. 

[drjdpowell]

Your problem is that you are sharing a single Event Registration between two parallel event structures.   Events are not designed for this and have this odd behavior.  Crete a separate Event Registration for your helper loop.

[joerg.hampel]

Of course, James. That escaped my tired eyes 😞

[FabiolaDelaCueva]

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@drjdpowell wrote:

Your problem is that you are sharing a single Event Registration between two parallel event structures.   Events are not designed for this and have this odd behavior.  Crete a separate Event Registration for your helper loop.

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For a detailed explanation of why we should not fork the Event Registration wire, check out this post:

https://forums.ni.com/t5/Delacor-Toolkits-Discussions/Registering-to-broadcast-events-from-many-modu...

The general rule should be a Register for Events Node for each Event structure (with dynamic event terminals visible) handling events.

[M.Lichtenheld]

Thanks @ all. Problem solved.

That way it works great. 

[drjdpowell]

Any mention of randomly missing events should immediately make one think of a shared event registration.  I still remember debugging this in one of my applications 10 years ago.

[joerg.hampel]

Makes me realize that I do mention a second event registration node in my article, but I do not explicitely state the importance. I'll edit the text accordingly. Thanks again for pointing that out, James.

Edit: Update done.

[drjdpowell]

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@joerg.hampel wrote:

 ...in my article,...

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Can't post an image in a reply to the article, so a suggestion here.   Remove these wires, as you don't need them and they reduce readability of what you are doing.  

[psmorris]

That's interesting James, I knew you didn't need the input wire (unwired = unchanged) but I didn't know that you don't need to wire the output of the register for events node... I always thought you had to "update" the event structure after changing the registration...

Nice to know!

[joerg.hampel]

I'm always having a hard time with these "seems to work without" things, as it's hard to find official documentation or comments about these things...

Agreed, the LabVIEW help states "Registered events stay registered until you explicitly unregister them [..]", so wiring an event source that doesn't change is unneeded.

With the Event Registration Refnum going from the Register For Events node's output to the Dynamic Event Terminal on the right side of the event structure, I'm not really sure if I agree that deleting this wire makes the code more readable - but that might just be me having to get used to it.

Anyway, thanks James for taking the time to look at the article and point those things out!

PS: Edited for clarification