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Ducc

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  1. Ducc

    Encoder + DAQmx

    The DAQ Assistant is doing stupid things. If I disable the z-index feature, the main program works. The only problem is I need the z-index. Otherwise, the encoder doesn't stay zeroed. If I just run the VI in Figure 1, everything works perfectly! The encoder is always zeroed and the z-index behaves. But when Figure 1 is called from another VI, it starts acting stupid. Even more annoying is that when some VI's call it, it doesn't happen. I can't figure out what it depends on. Maybe some loop configuration? I might go insane.
  2. Ducc

    Encoder + DAQmx

    Hi, I've recently purchased an NI 6220 daq card to work with my encoder. It's all wired up correctly (as far as I can tell), and I can get the card to read the position of the encoder just fine. Figure 1 The extra stuff just makes sure the output doesn't go negative or above 6.28 radians. Now these two screenshots show the VI that uses the encoder code you saw above (Figure 1). The grey icon "encoder" is Figure 1. Figure 2 Figure 3 As you can see, the For loop switches from True, to False over and over until the loop ends. When true, it takes data. When false, it just waits. Both true and false cases check the encoder to see where it is. The problem: when the encoder moves from the daq section to the waiting section, the value of the encoder jumps to a value of 2.0xxx radians (which is probably the z-index triggered value). The encoder is NOT in the position in which the z-index should be triggered! I can't not reproduce the behavior in another VI, and replacing the encoder subvi with a new link does not fix the behavior. Please let me know if you have any idea what might be going on. Thank you very much, -James
  3. The problem is the adlink DLL doesn't seem to want to work. I may be doing something wrong, but I've done it successfully before with other DLL's. It's not that hard, right? Just link the DLL, tell it what function to use, and add the necessary inputs and outputs? The reason I can't just buy different hardware is that this program will run on multiple machines; I'd have to buy a lot of cards. If I can't get the DLL working, is it my problem? Can Labview work with all DLL's?
  4. As the topic suggests, I'm trying to get an ADLink PCI-8133 DAQ card to work with labview. I'm using the card to read the position from a stepper motor. ADLink has a labview package (DAQ-LVIEW PnP V1.21.zip) but it does not support the 8133. I think a competent programmer could write all the Labview drivers (assuming they had access to the dll's) in a week, which leads me to suspect the dll's written for the 8133 are incompatible somehow. Any suggestions? What do you do when you come across hardware that won't work in Labview? Are there any workarounds? Thanks, -James
  5. I would also like to know where to get a "standard deviation of the mean" VI. There seems to be so much missing from the Student Version of Labview 7.0. Maybe I just can't find it?
  6. Hey, I have some data that should be roughly linear. There is the chance for outliers in the data, and I want to remove as many as possible. From my readings in statistics (of which I am largely ignorant), 2-d data filtering is really a function of the data itself; in other words, it's hard to filter the data if you don't know what it looks like. However, since my data is linear, I see no reason a generic filter wouldn't work. 1. Is there a place where I can find filtering VI's for linear data, available for free? 2. If not, are there techniques you can recommend to write my own? Thanks! -James
  7. I was about to post the same question, except for Excel (or any spreadsheet) files. No matter how I wire things, I'm getting broken wires and "bad data type" errors.
  8. oooooh! Yea, that's exactly what I wanted. Thanks
  9. Heh heh. I did didn't realize I had already done it before I posted that. I think I need my head checked. So my questions changes. Is this the most efficient way to do this? I'd describe the process, but I imagine you can look at the code and understand better than reading a description.
  10. Hi. I've tried to find a good guide for this, but I'm coming up short. I have a set of data that I need to break out of an array, do some stuff to, and put it all back together. I seem to be able to get the data out, but I'm having a hard time putting it back in. It seems as if LabView don't care if it's a 1d array column, or a 2d array row. Here is a graphical description of my problem. Can someone point me to a good "labview array reference", or give me some hints here? Thanks! EDIT: I should note that I'm also concerned with speed. The faster this operation completes the better. Millisecond saving is valuable.
  11. Yea, I didn't really understand that post. I figured out how to make it work, but I don't know why it does.
  12. I apologize in advance for my vocabulary; I'm not foreign, I just don't know what to call stuff. I have a case structure inside a loop (state machine), with the case selector wired to a list of available cases (you know, the dropdown box thing that everyone uses for state machines). I had Initialize, Clear Data, Run and Save Data in that list and the case structure showed the names at the top. Everything is good. Then I added "No Event" to the list and all of the sudden the case structure switched from names to numbers. So I undid what I just did to go back to the names, and this time I manually added the case to the case structure's list. The case appeared in red (is this bad?) but at least the name is written out. I can't get the list to include "No Event" (or anything) without the case structure going back to numbers. Is there a limit on the number of cases you can include before it only shows numbers? (um, I just put quotes around “No Event” when I placed it in the list. It didn’t go to zero but it didn’t show up in the case structure either. So I deleted the quotes and it worked. What’s up with this?)
  13. Cool, thanks guys!
  14. Oh, I forgot! Some NI rep told me about some way you could make two loops that operated independently of each other... one loop controlled the GUI, and the other loop did all the machine interfacing and junk. That way, you could let the user do things while something else was working in the background. What's that all about?
  15. Hi, I hope this hasn't been asked a million times already. I searched. I have some experience in Labview (I wrote the somewhat basic software that my lab uses) but I don't consider myself a programmer. I'm an engineering student that sometimes has to program to get work done efficiently. That being said, I need help with the "rules of labview". I've been charged with writing a couple other programs over the summer, and I'd like to know things that regular programmers already know (OpenG is good?). I’d like to learn more about state machines. And so on. Are there any good labview resources out there? I need explanations about how things work, and to be exposed to things I'd never have considered (state machines). Thanks! -James
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