styrum

The NI definitions of tag, stream and message/command are given, for example, in this cRIO guide (p. 29): http://www.ni.com/pdf/products/us/fullcriodevguide.pdf

It is indeed amazing and sad how attractive and popular "straw man argument" is. I won't even say anything else.

The matching discussion on NI forums: https://forums.ni.com/t5/LabVIEW/Eleven-Ways-to-Update-an-Indicator-from-within-a-subVI-Their/td-p/3938618

Yes, checking the watchdog queue takes a lot of time (if not most of) in each sender iteration. Please check out a "sequential version" in the latest posts or try putting a Disable structure around those Preview Queue Element nodes in the sender VIs (you will have to stop everything with the stop button on the toolbar of the Main then).

styrum Member ‎06-18-2019 04:17 PM Set Control By Index added. Wow, it is fast! "Speed" calculation in the "sequential" version corrected to count the iterations of the receiver loops. Fastest update of indicator from subVI (5).zip

Ok, OK, my bad, I left Debugging enabled. This is not a commercial app. This is is just some "food for thought", and something to play with, which you would otherwise not have the time to put together yourself. But now you can find some time (much less) to play with it. The goal was to get people to play with it, find flaws, "unfairness", etc. So I am glad that happened so quickly. Here is a version that has debugging disabled plus a "sequential" flavor of the whole thing. Some disclaimers right away: 1. Yes, I deliberately do not count the iterations completed by sender loops but not completed by the corresponding receivers by the time the senders are done, because I do want to count only fully completed "transactions" in evaluating "performance" 2. No, I don't say that lossy and non-lossy methods are comparable "1 to 1" in general context. But for the declared purpose of this particular experiment, updating an indicator in a UI VI, where the user is interested only in the latest value, it is fair to put them "together". Fastest update of indicator from subVI (3).zip

Sorry, I only have LV.2016.

Well, the very point of putting together this code is for people to see the numbers for themselves and that I didn't "cheat" on any of the tested methods to make some look better than others. Their significantly different performance numbers are real. In summary, the main findings are: 1. (Widely known) Passing a control reference to a subVI or a VI running in parallel to the VI where the control(indicator) is located with the purpose of using that reference to update that control/indicator is the worst you can do. 2. (Not so well known) Using "user events" in event structures for the same purpose mentioned and moreover, for implementing asynchronous communications in messaging architectures between "modules", "actors", parallel loops, etc. instead of regular queues and notifiers and now channels is (softly speaking) not a very good idea either from the performance point of view. 3. Even the fastest "channels" are not better than the "good old" notifiers and queues. At least channels give more features and allow to do things impossible before. Which hardly can be said about user events. DQMH is one of the frameworks which rely heavily on such use of event structures one can recall right away. There are others, I bet.

Yes, I know, you wanted to do this some day too. So I did it for you. Just run (and then stop) the Main VI from the attached set (Saved in LabVIEW 2016 32-bit). I suspect (and hope) the numbers will be quite a surprise and even a shock, especially for the fans of one particular method and some very aggressively promoted frameworks which use that method. Fastest update of indicator from subVI.zip

Maybe that will work too (again with a control, not with a constant). But there is no explanation there regarding the type expected as the Conpane (variant) parameter of that Set Conpane method. How do we get that Conpane from a VI we want to take it from before we can feed it to that method?

OK. So OCD is "obcessive compulsive disorder" I figured. Sorry, sickos patients, my native language is not English, but I still know what past participle is and even, for example, when to use past perfect tense in English (How many Americans do?).😋 "Cast Operator: () (programming) A type cast provides a method for explicit conversion of the type of an object in a specific situation. v. cast, casted" (https://english.stackexchange.com/questions/94565/can-casted-be-the-past-tense-of-cast)

For whoever is looking to do anything like this or anything else as far as programmatically changing code in a VI goes, I think I should remind that the best way to find and get a reference to any object you want to mess with on the FP or BD of the target VI is one of "hidden gems", <LabVIEW 20XX>\vi.lib\Utility\traverseref.llb\TRef Find Object By Label.vi

Thank you, Darin! That's exactly what I needed! By the way, what does OCD stand for in this context? BTW2: After calling Change to Constant the constant appears instead of the terminal exactly at the same place the terminal used to be, just as if I right-clicked on the terminal and selected Change To Constant. Well, at least in LabVIEW 2016.

I want to use a Call By Reference or a Start Asynchronous Call node in my TEMPLATE code. Which means I MUST have a type specifier constant (or control) wired to the Open VI Reference. In my CONCRETE code created based on the template code using VI scripting I need to replace the type specifier, or rather the VI which that type specifier extracts the connector pane from, so that the Call By Reference (or Start Asynchronous Call) node can use a new connector pane within themselves instead of the one it has in the template code. Normally (manually) we just drag and drop a VI with a desired connector pane onto type specifier constant or control. But how can we do that (tell it which VI to use) programmatically?

How can I programmatically change the VI which such constant uses (which we just drag onto it normally)? It is a just a "Constant" class according to its ClassName and can not be typecasted to anything else and doesn't seem to have any property or method to set that VI.