Jordan Kuehn

The (advanced) software track seems light, but I'm going into this with some reasonable expectations coming out of the pandemic and also the rebranding as a smaller event. At least that's what I'm trying to do. https://www.ni.com/en-us/events/niconnect/austin.html#pinned-nav-section4

I'm hesitant to download and open/run this. Do you have some screenshots/snippets? Anything you'd like to discuss about it?

I use this on cRIO with the system exec vi: timeout 0.1 ping -c1 127.0.0.1 Replace the 0.1 with the time you want (s) and the 127.0.0.1 with whatever IP address or hostname you want. I use this to determine if I want to attempt to open a shared variable connection to an expansion chassis since the timeouts on that API do not work.

I have approval for the trip and will be bringing a few other engineers. LAVA BBQ happening?

My simple test is quite like yours. It failed without the expected length wired. It worked with it wired. Thank you for the example. I will look into adjusting the inflate VI to auto-run a few more rounds, thank you for the suggestion. I just provided the big picture use case if the additional context might shed some light on what I'm after. Definitely working up incrementally to using it in that implementation.

So I just tried that without success. I had several screenshots to post of what I did, etc. and then I tried it with providing the expected length and it worked just fine. Is this input required? I read the description where you say it will work for up to 94% compression unwired. I'm compressing a JSON string of basically an array of clusters (quite compressible). Would it be disadvantageous to wire a sufficiently large constant to this input rather than bundling the actual expected output with the data? It did also work in when I tested with a large input. My use case here is to reduce bandwidth requirements when transferring JSON encoded status information via MQTT to a 3rd party system (non-LV). I hope to give them the requirement of inflating via zlib after delivery and then proceeding to use the JSON data as they like.

I will give it a more thorough test! I copied from one VI indicator to a constant in another application instance. I think. Knowing that it *should* work is already very helpful. Thank you both.

I can split this off onto another thread, but I copied a deflated string produced by Linux RT and tried to inflate it on Windows and it did not work. I took the original data and deflated/inflated all within Windows just fine. Is there a compatibility issue between the two OS implementations?

I agree with ShaunR. Despite it being posted as replies to several posts all in one day, I don't think it's overly spammy and they were mostly relevant to the discussions at hand. It was enough to get me to poke around at the product page and file it away in my mind should the need arise.

Got it! I got the files installed, put them in a package build spec in the project explorer. Configured the source file to go where you said and wrote a simple script to run the ldconfig as a post install action. See screenshots below. I installed the package and ran the same test code that errored on deployment and it worked great this time. No manual moving of libraries on my end. Package attached. Thanks for all the help! openg-zip_1.0.0-2_x64.ipk

I would be happy to see if I can build a package to share or at the very least move the files over to get it working in my application. However, I do not see that directory on my machine. I did reinstall while running VIPM in admin mode but still nothing. I opened the vipm package via winrar and looked around inside and this is what my post install vi looks like (I'm in Windows):

I do not see a way to do this in 2021. Perhaps it is because I have the Linux RT image installed and not a custom image to begin with, but right now, even in MAX, I only see the options to configure feeds and to install packages from those feeds. If a package were available or I could build my own (I’m not sure all of the details for this library installation) I can put it in my project and install it as a dependency without it being in the official NI feed. Am I missing something here? I remember the old way of installing software, but I do not see where that is available anymore. I’ll grab some screenshots when I get to my desk if that would help. Edit// I think it was like this in 2020 as well now that I’m looking back. I believe it’s the Linux RT image that switches the software installation dialog. I can play with that some too a little later today to see if I can get it working like Mads described. But that would not work long term for me since all of my development is utilizing packages (and SystemLink) now. Edit 2// Here is what I see when selecting the base system image to use. I believe if I go with the "Custom Software Installation" it will give the old method back, but that is described as "Legacy". And as you can see here, I only have the ability to add packages via the configured feeds. Some NI feeds, some my own.

Is this still true in LV2021 with Linux RT? I am getting the same error, but the software installer has changed in current max and utilizes packages. In opkg I see a few perl and a python zlib package available, but not lvzlib.

Perhaps this same issue that is a bug, per AQ's reply: https://forums.ni.com/t5/LabVIEW-Idea-Exchange/LV2021-Deactivate-Wire-Auto-Routing/idi-p/4183557

Thanks for the link and bringing it to our attention! I focused on this part (my emphasis added):

FPGA certainly. I have use for the code I posted when say thresholding a value and wanting to ensure that it has exceeded that threshold for a period. That value could be anything. A plain signal or it’s derivatives, a float switch with a digital input, etc. At high rate in an FPGA you’d normally use it for say a mechanical switch that makes intermittent contact rapidly as the contacts first come into contact with each other. I’m sure there are more examples!

That certainly fulfills the debounce nature in a more pure manner, debouncing both low and high. Mine is more of a conditional latch with optional single pulse output or latched high output. I think you got my point though about using a counter. As far as it being pretty or not, I don't know that I'd ever look at the BD again after finishing testing. The counts can be adjusted based on where you use it. Certainly sample rate will be a factor, but also expected noise/bounce vs desired responsiveness.

I have something like this that I use.

So that's what AQ means. Apprentice Questions?

Oh that’s perfect. Just like OP on that post it’s the reboot time that’s the issue for me. This line is what I was missing: /etc/init.d/nilvrt stop && /etc/init.d/nilvrt start I’ll give this a try. Thank you.

Rolf, I've been looking for this information myself. Not quite in this use case as requested, but simply to restart the application. Do you have any reference for simply restarting the runtime engine and relaunching the configured rtexe? SystemLink is capable of doing this, but I haven't managed to figure out how yet.

Awesome, I will give it a try. The cluster writing would be great as well!

So, I think you have pulled it apart fairly well in your summary. I believe the issue with the regular Write function is that it can fragment the data and builds the index on the file to take care of this. That combined with flushing, segmenting file writes, and defragmenting after completion will address it for many use cases. The waveform issue is that first the advanced write won’t take the data type due to the properties next to it, and that’s all it is like you said, and array of doubles, some standard components (t0, dt), and possibly some variants. Then second even if you were to write an array of doubles using the standard write vi it is not as performant. When using the advanced VI you specify the block sizes and it streams that to disk exactly as written. (I’m sure there’s a little more complexity at the c level here.) So you must write the same size every time, but it is quite fast and does not leak memory. So, I see a space here where in general advanced tdms functions could be chosen given the condition that subsequent writes follow the same size as the first write (allowing to read that and perform the configure), and then to further that, could automatically unbundle a waveform type to package the properties up and write the array. It’s a thought, and something I’ve encountered a few handfuls of times over the years and it’s a pain every time.

Hooovah, I appreciate this toolkit and the work you've done to make it. I have a common problem that I run into and eventually just have to bit the bullet and roll my own solution. When streaming large datasets to disk I have to use the TDMS Advanced vis to get it to avoid a memory leak. It is even worse with waveforms, though I would like to be able to write those directly you can't with the Advanced vis. So I wind up stripping the t0 and dt off and saving as waveform components, flushing the file to apply them, configuring block sizes, etc. Could this library be adapted to use the more performant vis, with some preconditions, say that all subsequent writes must be identical in size/composition, so that I can stream waveforms to disk? I attempted to use your size based file writer and ran into the same memory leaks I encountered when using the regular tdms files, described here.

Anyone have any news if NI will be bringing this conference back? I see the Austin Convention center has a listing for May 24-26, 2022.