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LabVIEW Information

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    LabVIEW 2014
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wohltemperiert's Achievements


Newbie (1/14)



  1. Wow, thanks for your information. I wasn't aware of this behaviour at all and I was just about to implement the VISA lock solution. I will read it.
  2. I talked to a friend of mine and his proposal is to use the VISA lock, which works in a similar way as DVR.
  3. Thanks a lot for your quick reply and sharing your presentation! I'll watch it.
  4. Dear al, I've got an architectural question for the serial communication. I am currently working on a machine which is communicating with LabVIEW program on PC. There are totally 4 COM ports that are involved. COM1 (RS485) is used and shared by multiple threads/users, where as COM2, 3 and 4 (RS232) are used only by a its own thread. I created a VI for send and receive with time out and so on. In order to prevent race condition of access to COM1, this send receive VI is not re-entrant. On the other hand, however, I need this VI to be re-entrant, so that it can be used by communications of COM 2, 3 and 4. Do you know how I can solve this dilemma? Thanks a lot!
  5. Hi JoeQ, in my current application, I am dealing with 16 NI USB DAQ devices, with each of them running at 200Hz and recording data (DBL) at 3 analog channels + 1 channel time stamp simutaneously. You said, you normally had 2 data paths with one of them for display. Does the data path for display have some kind of a fixed data length? Could you please describe a little bit more, how you did it with peak detection, or you could suggest some other ways? Thanks in advance!
  6. Hi drjdpowell, thanks for your reply. I think your method is a really elegant and more resource saving way for dealing with the issue, if zooming is not needed. I've also tried to think about a simular solution in terms of keeping only the data to be plotted and dumping the raw data, when I was going to finish my application without the zooming function. But I was not able to figure out the way as you did by compressing the array. Now I am going to try out the alternative with SQLite first, keeping in mind that there is another alternative. Hi Manudelaveg, I've been asking myself the same thing, when I was looking for a ready-made solution for my issue. I have no experience with the TDMS format and I think it could come into consideration, if it provides the possibility to "select" and decimate data from a large database as SQLite. Do you think it's possible?
  7. Hi Schaun, I've attached the error message. My assumption is, the time stamps for the start and end of the time range are causing the error message, since they are formatted using the system default decimal point, which is in my case a comma. I've tried the following workarounds by forcing the vi to use point as decimal point each time data is converted between string and value, and the example vi seems to work now with comma as default decimal point of Windows setting (see attachment): - adding %.; to the format string - replacing the VI "SQLite_Select DBL" with "SQLite_Select Str" and adding the Value False to the VI "Fract/Exp String to Number" (this modification was also done for the timeout case) Do you think these workarounds would solve the whole issue with the decimal point? Are there any other aspects I've neglected? Thanks for your reply in advance!
  8. Hi Shaun, thanks for the rapid reply. Your tool kit seems to solve my whole issue which actually also includes the aspect of zooming. I still have some questions and I would appreciate it very much, if you could provide me some answers: - Is it possible that the tool kit also works with numbers with comma as decimal mark (for Germany), coz when I first tried the zooming out, the VI "row col count" has reported error and the error was eliminated, after I had change the Windows settting for decimal mark to point. Or maybe you know a elegant workaround, without having to change the setting on Windows. - Is it possible to manage and make parallel access to several "tables" within the same database or they have to be held in different databases? - without going through all the examples and documents: Is there any description for the syntax used to where clause? Thanks for your reply in advance! Best, Fred
  9. Hi everyone, my current application has to deal with real time data acquisition (200Hz or above) on multiple channels simutaneously and plotting the acquired data on XY-graphs (including decimation) in real time. Such acquisition typically lasts several days and a very large amount of data is therefore being created, so that the memory of the PC could run out very quickly, if the data is kept in the memory of the PC. Since the XY-Graphs have to be replotted periodically (at least quasi in real time), it seems to me that, the whole range of data somehow has to be available, no matter if decimation is being performed or not. What I have been thinking about is, trying to stream the accquired data to the hard disk and read the decimated data points into the memory for plotting. Has anyone ever dealt with this kind of issue and could provide me with some tipps or experiences? Thanks in advance! Best, Fred
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