Tim_S
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Posts posted by Tim_S
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John was hoping to have a single file for each plugin to simplify distribution. Given the uncertainty of working with PPLs, deploying a directory instead of a single file might be the simpler solution.
I found a NI Forums post on how to combine VI server and packed libraries. I tried it with LV 2010 and had no luck to get it work with a class.
Tim
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Well, I built some sample project that demonstrates the concept. And it even kind of works.... sometimes.
This might be what you're looking to do. I unfortunately don't recall where I found this code to give credit, but it demonstrates how to use plugins in LV.
Tim
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I'm using an old SCXI system for all analog measurements - thermocouples, 4-wire RTDs, current inputs. I average measured samples to increase accuracy, especially on the 4-wire RTDs. The RTDs happen to be connected to a mechanically multiplexed module. The NI manual suggests scanning multiple samples from one channel before switching to the next channel to avoid wearing out the mechanical multiplexer. The channel switching is actually audible. Imagine switching a mechanical multiplexer 100 times/second - it would wear out quickly.
Wow, I remember that hardware from LV 3.1 days... My best guess is they are recommanding you keep switching tasks of 1 channel each. This could be perfectly fine if your monitoring and updates involves seconds (versus milliseconds) and your channel count is low. It wouldn't be my preferred method, however that may be the answer if that's the hardware you've got to work with.
Tim
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Yes, it's a WAG ...
Okay, there's one I'm not familiar with. What's WAG?
the whole calling chain has to go away
Just to make sure I understand this ('cause I've *cough* occasionally been known to be wrong)... If I have TopLevel.vi which calls SubA.vi which calls SubB.vi, and I put a request deallocation in SubB.vi, then TopLevel.vi has to go idle before the deallocation occurs?
Tim
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Do any of you have experience with the Request Deallocation function? I'm wondering what proper use is.
I shall be interested in how this gets answered. I've put it in code where I knew there was a large amount of memory usage, but I've not seen performance improvements in how I've used them. A contractor we had in put them in every VI he created, but that doesn't seem right either.
I guess I have a few questions with regards to LabVIEW and memory as I've never created any LabVIEW applications that manage large data spaces. Is there a hard limit on what LabVIEW 32-bit is capable of? Am I looking at a 3 GB or so ceiling? I'd never expect to have more than maybe 500 MB of data resident in memory at one time for extreme cases, but the application will be managing gigabytes worth of data space which is cached to disk and can be called up on demand for display purposes.
I've had Windows XP terminate a program (happens when program uses >= 2 GB) before LabVIEW 8.0 was unable to gather more memory.
Tim
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I've had error messages that say things like, "If you're seeing this error, the developer who wrote the code didn't read the documentation. Find him and smack him." But they tend to be few and far between.
A former coworker put an error message in that said (paraphrased) 'this condition can never happen so you'll never see this message'. Unfortunately it did happen and we received a call from an irate customer. I've been rather cautious about what I put in my error messages since, especially since I wouldn't put it past some of my customers to smack me.
Tim
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We put together test equipment. General rules for what to get in a PC for us are:
- 4 GB RAM, possibly more if it's a NVH application
- Faster dual-core processor. The only time we used 4 cores was with a LabVIEW 8.0 application and 3+ cores slowed the test by ~40% due to multi-threading. We've not tried more than two cores since, so I can't comment on what the improvement has been since.
- Does the PC has enough ISA/PCI/PCIe slots (yes, we still occassionally use one ISA card... baffling)
Video cards have only come up once when a customer wanted 4 monitors from one PC. Otherwise, the screens don't update that much information that disabling updates for a moment doesn't take care of performance issues. The performance issues I run into is with multi-column list boxes when doing something like setting colors of individual cells (red=fail, green=pass), and populating tables. Graphs don't give me issues; I've tested putting 10,000 waveforms of 16k points each on a graph and had a slight performance hit when zooming in and out.
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Lots of good discussion. Just my mesely $0.02...
This doesn't look like a bug to me, but as operating as designed. I don't believe is should produce an error, however I can see it producing a warning.
A use case for this that I can think of is a Watchdog Timer, though, honestly, I would add the non-Timeout event case in as well to clarify the code.
Tim
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Is it literally a second computer which you log into, update your local version and run the build specs, or is there a more elaborate interface which I'm missing?
We have "build machines" which are virtual machines, but you've got the idea for what we do.
Tim
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By definition, shouldn't only unread posts be listed on a page called "Unread Content"??
I'm guessing you're still logged in. I was logged out a couple of times (gotta love IE) and the unread content didn't update.
Tim
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And lastly is there any good tutorial on OOP in Labview? It sounds interesting and I would like to learn it.
There are good tutorials on NI's website.
Tim
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we are currently looking into replacing our current hardware (made in-house). In a few days we'll visit an NI Test&Measurement roadshow; I'm pretty sure the NI folks will all go like 'yeah PXI is ideal for your application' but I'd like to get some more objective information first.
You'll want to talk with your local NI representative about your application. You'd have to get much more indepth into what you're doing to help you with a solution, which is what many of us do for our day job. As such I don't think you're going to get a lot of help from these forums.
Otherwise...
The DAQ synchronization is a hardware and driver level capability; some NI cards can do this so pay attention when you pick your hardware.
I'm not certain if LabWindows can be compiled for the RT OS. LabVIEW can be.
Tim
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Excellent! Do they perform Masochism Tango as well?
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Any ideas how to troubleshoot?
What do you mean by losing control?
Have you tried watching the front panel with highlighted execution?
Tim
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Does anyone know how to do the same programmatically in LabView?
I believe you can get the same through .NET if you're using Windows. Unfortunately I'm not finding code that does this in my "oh, neat" library.
Tim
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I'm looking for suggestions on how to best handle UI events (stop, start logging button, possible menu options, etc.) within the the following design:
producer loop: serial comm with proprietary control system
producer loop: serial comm with NI analog related hardware
producer loop: serial comm with heise pressure transducer
consumer loop: parse data/strings/responses from producer loops, updates UI (w/ parsed data, graph, DI/DO LEDs, etc.)
Perhaps another loop (events) to monitor UI events?
another suggestion?
The answer is it depends. It depends on what everything else is doing, how fast it has to respond, and the requirements of the system and the systems it's hooked to (the serial links in this case).
You can perform UI monitoring in one loop and the other tasks in other loop(s). If you are going to receive messages and have to turn a response around in 1 second, then a single loop may be fine unless you have to always receive data and save data, which will block execution if the user has to interact with a file dialog box. (I phrased that awkwardly, but I think the idea is there.)
Tim
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See this.
Excellent! In multiple languages even!
That's getting bookmarked. ('Cause I know I need a swift kick every now and then!)
Tim
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Can please send me the simple code to communication via Ethernet.
Why not look at the example code that ships with LabVIEW?
Tim
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I was at Lazer Zone, which is a pizza/laser tag/mini-golf/game place and happened to look at this touchpanel control for a room where you shoot foam balls at each other. The controls looked familiar. I realized the control system for the room was written in LabVIEW. I was able to verify this when an employee came over and logged into the system to start the game by the icon in the corner of the pop-up.
This geeked me to where I had to point it out to people I was there with. They thought it was neat, but, well, they aren't LabVIEW programmers.
Anyone found LabVIEW used in other unexpected places?
Tim
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That would be a lumbar microdiscectomy, to be exact. Yup, today I am getting my back opened up and parts of my spinal column removed.
Good luck with the surgery and recovery.
I'm not supposed to sit for more than 30 min at a time. At the moment, sitting is very painful and I'm lucky to get 10 min in a chair before the pain becomes too severe. That would be why I haven't been on LAVA much -- it's hard to type when you're walking around.
People seem to text quite well with their iPhones and Blackberries while walking. That might not be so good of an idea, though, as people have been known to fall into manholes.
Tim
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My problem is coming up with an algorithm that will measure the line and relay coordinates back to my program where two stepper motors will move the solar panels into a better position.
I recommend taking an actual image (really a set of images) and trying to evaluate each one. You're going to wind up using filters to process the image so you can get rid of the extraneous and measure what you're looking for. Posting code of what you've tried will provide more fruit as it shows you've at least tried something.
Tim
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Ok, but I do not understand how to stream to the raid disk without having to go through the processor.
I presume that you still have to use the IMAQ driver and do a grap on the camera and then do something with the
imaq image. It seems that NI only supports triggered image capture not video.
The driver and hardware handles the streaming to disk.
You can perform video capture with NI hardware. Check the examples as there is one in there (assuming you have IMAQ driver installed).
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My question is what hardware is recommended to support the video portion of the system.
I've not tried what you're proposing, however it seems you are going to be sending a lot of data strait to disk. RAID, of whatever flavor, itself won't help that, however it may let you link enough hard drives to have the space you need. I believe your bottleneck is the hard drives ability to write data fast enough. Anything with very high bandwidth may also be designed for a computer room and not a shop floor (15k RPM drives do not survive long when exposed to 108-degC temperatures instead of nice A/C environment).
Tim
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We started with best intentions but deadlines forced the usual shortcuts.
Sadly I quite understand this...
Image Encryption
in Machine Vision and Imaging
Posted
Are you looking for color, black and white or thermal? What resolution do you need? What frame rate do you need? Are you looking for USB, firewire, or ethernet connection? Is the camera in a hazardous environment? What's the distance from the camera to the area you are looking at? How big is the area you are looking at? You've got these and a whole mess of other questions to answer to pick a camera which are all based on what you're going to use the camera for. NI does have some vendors that they have partnered with, which you can get to on their website; the salesmen are typically very helpful about helping you pick out one for your application.
Good luck
Tim