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smithd

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Everything posted by smithd

  1. theres no such thing as determinism over standard ethernet... I believe cdaq will automatically pack the digital lines pretty effectively, but you can just use task manager (on win10) to see the network traffic, else use resource monitor. I wouldn't suppose there is any issue with the network. In fact, I wouldn't even expect that function to be blocking for an ethernet device, but maybe it is. Does anything else happen in task manager when you see the blip? Does it still happen if directly connected?
  2. in theory i think you can use the 'swap values' primitive between the dvr read and dvr write to swap the specific handle over into the dvr, but that may be wrong. tdms also has an e-dvr option: https://zone.ni.com/reference/en-XX/help/371361R-01/glang/tdms_advanced_functions_dataref/ that should have almost no memory overhead.
  3. fair enough, but I guess as a bottom level statement I (perhaps misguidedly) trust windows to do a better job of cleaning up failed processes than labview to clean up dead clones. This is especially true if the workers are doing anything that isn't completely core to labview -- for example, calling 3rd party dlls (or imaq).
  4. Whining mode: I know they are your and Jeff's baby but the last time I had a small (1 VI doing some pipelined processing) greenfield opportunity to try them out they were pretty cool, seemed to work well in the dev environment (if a bit slow to do all the scripting steps) and I was excited to be using them...and then app builder happened. Quickly gave up trying to make my single VI build, tore out channels and replaced it with your other baby, and it built right away. Its unfortunate because the concept seemed to work as nicely as claimed, but...app builder. App builder truly ruins all good things 😢 Helpful mode: This is a key line -- I wouldn't necessarily trust myself to write an application to run standalone for that long without any sort of memory bloat/leak or crash. My personal recommendation would actually be to spawn them up as separate processes. You can build an exe which allows multiple instances and pass parameters (like a tcp/ip port) to it. If one fails you can restart it using dotnet events or methods (or presumably win32 if you, like shaun, have an undying hatred of dotnet). You can also use a tool like NSSM to automatically restart the supervisor process (assuming windows doesn't break in this time period)
  5. Eh, I'm totally fine with security experts making it so I can't shoot myself in the foot. My main goal for my secure networking layer is to give me the most reasonably secure connection to another device without me having to know. They do have some protocols available but disabled by default (I think this includes SSL3). FIPS, as I understand it, is less about the algorithms and more about certification of a specific version of an implementation of the algorithm, which is then ossified and never changes even for security fixes. So to their point, its about checking a box, not providing security.
  6. Some would say avoiding FIPS is a feature And yeah, it will be a while for 1.3 -- they refused to do anything until it was actually standardized and now they are working on it. Seems like their attitude is "1.2 isn't broken yet" which makes sense. Their focus from the start was to fork openssl and clean it all up, which they seem to be making good progress on. I wouldn't have expected any correlation to the openssl version numbers at this point.
  7. libressl seems to have a better focus on stability, plus their api is much better. https://en.wikipedia.org/wiki/LibreSSL When I wrote my little tls library i wanted to avoid the dll issue so what I did was use the callback variant of the api here and here and just used the built-in labview tcp api. The callbacks are run when the library needs more data to enter or leave, so I just made the callbacks write to a queue which I then pull from to feed the labview primitives. Its a much much much nicer api than all that openssl stuff. Openssl docs make my soul cry.
  8. Its important not to miss the details on that performance one. They went for the specific use case of very very underpowered devices, very infrequent sending of data, etc. For example they assume a new TCP connection for every data packet, unless I misread*, while on the DTLS/coap side they ignore security handshaking, assuming you have a factory installed pre-shared key instead. It looks like it also ignores the fact that CoAP uses a rest model, meaning a request-response cycle. If you include that information they are basically saying "UDP protocols with no reliability except a super super barebones re-transmit feature work better than TCP if you close and reopen the connection once per second"..which...yeah. *
  9. If you don't need to use labview, I recently used this tool: https://github.com/glexey/excel2img You can run direct from the command line or build it into an exe using pyinstaller.
  10. Lol. Sorry for sidetracking, but I tried to get it to even open and it crashes on my machine. If you believe a KB, at some point someone before me installed a beta version of nxg on what is now my laptop (seems unlikely). The fix is to uninstall nxg, uninstall ni package manager, "Remove any supporting NXG files in the root directory, removing any trace of LabVIEW NXG from the machine" and reinstall everything. I asked NI support what "the root directory" is I'm supposed to delete NXG stuff from and they told me it meant the C drive 😕. Find an unspecified leftover NXG file somewhere on the C drive and delete it. What a joke. Lol
  11. I've looked at it in the past. Seems weird to target devices with performance such that full http is too expensive to parse but with sufficient performance for dtls over udp and for parsing/returning json and xml strings. I just ended up using full http.
  12. I see, yeah I don't know of any movement on the ni side to improve data comms. Rabbit is 'available' via systemlink, but...requires systemlink. Its also just about 2020 and we don't have any secure network api built into the product.
  13. oh yeah i meant you just have to download for windows. I know its pretty easy to compile for lrt, but you have to do the compile.
  14. I'm confused by this question -- there is an available zeromq library if that fits your needs. Its not perfect but its good, and its up to version 4.2.5 (current main lib release is 4.3.2). If you don't need linuxrt support you can just use https://github.com/zeromq/netmq
  15. Cross post is here: https://forums.ni.com/t5/LabVIEW/Errror-538179-Modbus-TCP-IP/td-p/3999197/page/2?profile.language=en StephenD in that thread is correct. I don't have labview installed here, but the error literally just means that you are using the base class for something. The base class has no implementation, so I added an error which says "hey you just tried to do something with an uninitialized, dead base class". I added this error message because I think I had a case structure where I accidentally selected "use default if unwired" and so that case structure was returning an uninitialized parent object. Other situations to look for: Uninitialized shift register (ie action engine) used before initialized Pass object through a for loop without using shift registers -- if the for loop executes 0 times the output will be a dead parent object case structures as described above diagram disable structures you forgot to wire through You should be able to probe your code (turn on 'retain wire values') and you should see a point somewhere that the initialized object gets invalidated. Or you could put breakpoints in your action engine cases and see if one of the error cases is called prior to the modbus object being initialized. As a general statement I don't use action engines/fgvs because I find them to be confusing to manage, but then labview objects are also confusing to manage. The modbus master object is internally reference based and the wire can be safely branched. I would typically not do this either -- I'd have a single loop which talks to a device and is responsible for writing data to that device or reading data from that device.
  16. I don't really think the metaphor matches. Left handed scissors are obviously intended for we 10% and are marked as such. In your examples, its not clear who xctrls and ppls were designed for, nor what "using as intended" actually means. In contrast: left- and right-handed knives. They do this fun thing where they just steadily slide outward and make all your cuts super weird if you're using the wrong hand, but they still kinda cut so its very non-obvious. Its funny to watch, and its not really marked unless you look carefully at the edge, and you also have to know that you were supposed to look and check the edge in the first place, which many many people do not. And then if the knife slides off the edge of what you're cutting, you might just cut right into your hand. This seems like a more fitting analogy to xcontrols, myself
  17. I've definitely used it, although we ended up going with a different db so the code never got used for real. I think I had tried it on lvrt but I can't really remember. I tend to think that talking to a central db from an rt target tends to break the nicely distributed nature of the systems and so I'm more likely to use your sqlite on rt, but I get that for test systems and the like (now that PXI RT Linux is a thing) might be more likely to talk directly to a postgres database.
  18. https://stackoverflow.com/questions/39576/best-way-to-do-multi-row-insert-in-oracle
  19. i think if you put the img display in snapshot mode its synchronous? I agree that imaq needs refs, but why does it need named refs? Thats the part thats horrifying
  20. Yes, I don't really care about that, and I will use block diagram cleanup until its pried from my cold dead hands 👻 Some of the key parts (like the engine) are relatively neat (by my standards) but due to the complexity its definitely still a hot mess. And of course a lot of the code dealing with all of the data types is scripted because aint nobody got time for that. Your other comments are fair though, some definite mistakes were made in the design, but all told I think it does a decent job. Yeah, I made an aborted attempt (https://github.com/LabVIEW-DCAF/ModuleInterface/tree/StreamingAndEvents and https://github.com/LabVIEW-DCAF/ExecutionInterface/tree/StreamsAndEvents) but...then I left NI. The nature of labview merging is such that those branches are probably now useless edit: theres probably a few implementation-side branches too like https://github.com/LabVIEW-DCAF/StandardEngine/tree/StreamsAndEvents
  21. Labview doesn't provide a way to check the status of the TCP connection except by trying to use it. Serial modbus has no physical way to check the connection except by using it. In both cases you need to use it to see if it still works. On the master (client) side you will see any of the TCP error codes (56, 62 and 63 being the most common as I recall) for the TCP master. For serial masters, you will only ever see 56. I suppose some VISA-specific codes are also possible, like if there are parity bit errors or if you're using a usb-serial device that gets unplugged, that sort of stuff. Modbus protocol errors are - 389110 as mentioned above. On the slave (server) side you will never see an error from the data access methods because the access is local. You can check (via a property node, I think) on the status of all connected masters (clients) for TCP. Serial is 1-1 and has no concept of a connection, so I think it just tells you the last error to occur for the serial comms process.
  22. cRIO is all linux, PXI now supports linux: https://www.ni.com/product-documentation/55164/en/
  23. I wouldn't do this. Its probably ok in this limited case, but its possible to make labview crash in this way. A better route is the variant, which has the same capabilities (cast to an opaque untyped blob and back again) but without the danger.
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