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xtal

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Posts posted by xtal

  2. NI WEEK LAVA Roll Call

    in NIWeek

    Posted

    I'll be there as usual - Sat-Sat and staying at the Radisson (best pool - this high-elevation desert rat can't handle the Austin heat anymore).

    And I hope to never have to give another NIWeek presentation again since I gave at least one for every single conference until last year.

    I'm hoping Norm (hint, hint) or someone can keep me updated on what's going on and where folks are.

  5. Lotus Notes database

    in Database and File IO

  6. Annoying NI sales calls after visiting ni.com

    in LAVA Lounge

    Posted

    QUOTE (Michael_Aivaliotis @ Jun 4 2008, 04:23 PM)

    Anyone else annoyed at this?

    YES! Consider me also annoyed. And I don't think I was doing anything more than just clicking around and looking at new products and random other things. I did NOT click on the "call me now" or other type of link.

    However, that being said, NI isn't the only company that does this. I won't name names, but I was also browsing the content of another company's website and downloaded a couple of app notes. Within an hour, they were calling me and trying to do a hard sale on me. I told them I wasn't interested and was just collecting info, but I got at least 1 phone call and 1 e-mail per day for the next week. And that wasn't the most annoying part...each time I got an e-mail, they misspelled my name in a new and interesting way. If you are going to spam me to death, at least have the courtesy of spelling my name the way I typed it in the registration.

  7. Pick your niweek 2008 badge icon... NOT!

    in NIWeek

    Posted

    QUOTE (Aristos Queue @ May 21 2008, 06:13 PM)

    And, for the record, if you don't like the badge options, there's always duct tape and construction paper. Of course, that sort of defeats the whole purpose, finding those who picked similar icons who might have similar interests. If the icon set is open ended, there's really no point to the whole thing.

    I'd rather be unique and creative with my lovely origami/duct tape badge critter than pick one of the existing icons. But I always have enjoyed dancing to the beat of my own drum.

  9. TC CJC Accuracy

    in Hardware

    Posted

    QUOTE (ASTDan @ May 7 2008, 09:50 AM)

    The accuracy of the measuring device can only be as accurate as the transducer. Here's a table of TC accuracies I found: http://www.microlink.co.uk/tctable.html. Omega has simlar charts based on the number of coefficients you use to calculate the polynomial.

    In our specs, we usually use an accuracy of +- 3 deg C for TCs in general regardless of how we measure them. Also, TCs can drift over time depending upon what the operating temp is and oxidation levels. We've seen a 5 deg C drift for type K thermocouples used in high temps over the course 2-3 years.

    For situtations where we need better accuracy, we use precision RTDs.

  10. using labview at work

    in LAVA Lounge

    Posted

    I also work in a Biomedical company and use LabVIEW daily for automating the processes that manufacture our products, for profiling various equipment like ovens, and for data acquisition, charting, and analysis of R&D data.

    Like any other tool, once you learn how to use LabVIEW appropriately, you'll be surprised how much you can accomplish.

  12. Using scope_identity()

    in Database and File IO

    Posted

    QUOTE (Mike C @ Apr 28 2008, 03:02 PM)

    I have tried using a semicolon to indicate where each query ends but it did not work. I suppose the LabVIEW toolkit cannot execute more than one query per SQL statement. I did take a quick look at the blog and it seems that there is still a more than one query per SQL statement so it will probably not work. I'll give it a try though.

    The toolkit can definitely send more than one query at a time. It doesn't do anything magical under the hood...it just passes the string directly to the ODBC driver in this case. Since you don't get any errors from the ODBC driver that indicate problems with the connection, I can only guess that there is a syntax problem.

    Another option is to use the UDL file to connect and use the SQL Server driver directly. I've found ODBC to be difficult to work with and using the SQL Server driver is usually faster and has more functionality and supports more datatypes.

    Also, can you run each statement separately for testing purposes? Starting with a simple query and making it progressively harder until it fails will give us a better idea of what part is causing the problem.

  17. Memory Leak on Database Reopen

    in Database and File IO

    Posted

    QUOTE(jpc @ Nov 27 2007, 10:09 AM)

    We are using MS SQL Server 2003, and MS SQL Server ODBC Driver Version 2000.85.1117.0 according to the ODBC Data Source Administrator Drivers tab. When I set up the ODBC connection and run the connectivity test, it lists the driver version as 03.85.1117. The strings are going to be specific to the ODBC connection you make and the database you use, so I made them string controls in the demo VI. The ODBC Data Source Name was created in the System DSN tab of the ODBC Data Source Administrator.

    Well, John, I have a Good News/Bad News situation to report. The good news is that I have the exact same version and drivers for SQL Server and I had no problems creating a small table and reading from it using your VIs. I used both a UDL connection and a System DSN as you are.

    The bad news is that I still can't reproduce what you are seeing. The memory reported by Task Manager for LV doesn't budge regardless of whether the DB VIs return an error or not. Does your memory start disappearing as soon as you disconnect your Ethernet cable or should I let this run for a long time?

    So I guess we need to figure out what is different between your and my systems.

    I'm using LV 8.2.1 on an XPsp2 machine. My database is located on a networked machine and disconnecting my Ethernet cable creates the same error you are working with.

    Other than our LV versions being different, what else can you think of?

  18. Memory Leak on Database Reopen

    in Database and File IO

    Posted

    QUOTE(jpc @ Nov 26 2007, 05:22 PM)

    To confirm the leak in the Error Helper.VI, I commented out its use in the DB Tools Select Data.VI (see the 2nd attachment) and reran the test. No memory growth.

    I tried to reproduce the problem you are seeing and couldn't with the VIs you attached. Which SQL database app are you using, what driver and version, and what exact strings do you use to open the connection?

    Usually these types of problems are leaks in the ODBC database drivers themselves and therefore nothing that can be addressed or fixed in the database toolkit. Plus, if the problem is in that Error Helper VI, there's nothing in there that is specific to the toolkit...that's just plain LV code and would be reported as a bug in LV, not the toolkit.

    Please let me know if there is anything specific I need to do to reproduce this and I'll help report it to the appropriate people at NI. I only have access to SQL Server, though.

  19. Memory Leak on Database Reopen

    in Database and File IO

    Posted

    QUOTE(jpc @ Nov 26 2007, 05:22 PM)

    To confirm the leak in the Error Helper.VI, I commented out its use in the DB Tools Select Data.VI (see the 2nd attachment) and reran the test. No memory growth.

    I tried to reproduce the problem you are seeing and couldn't with the VIs you attached. Which SQL database app are you using, what driver and version, and what exact strings do you use to open the connection?

    Usually these types of problems are leaks in the ODBC database drivers themselves and therefore nothing that can be addressed or fixed in the database toolkit. Plus, if the problem is in that Error Helper VI, there's nothing in there that is specific to the toolkit...that's just plain LV code and would be reported as a bug in LV, not the toolkit.

    Please let me know if there is anything specific I need to do to reproduce this and I'll help report it to the appropriate people at NI. I only have access to SQL Server, though.

  20. Equalizer

    in LabVIEW General

    Posted

    QUOTE(EJW @ Oct 26 2007, 01:46 PM)

    Ok, here's one for you long time Labview gurus. I was writing my own media player in labview, and i thought it would be cool to add an EQ. Unfortunately, i have no clue how to do this. I am assuming I would use

    and band pass filter to get each band i want, then modify the amplitude somehow, and then, the part i really don't know, is how to combine it all back into one signal. Anyone want to take a stab at this?

    I'd appreciate any input, thanks much folks!

    We actually had an Equalizer demo we presented quite often that was part of the examples we shipped with the original DSP boards (waaayyy back around 1990ish - hey, you said "long time LabVIEW gurus"). Yes, it was a bank of bandpass filters. Those VIs are super old so I don't think I have them anymore. When I return from my business trip in a week, I'll make a note to look around in my old things and see if I can find something to help you.

  21. MySQL and LabVIEW performance issues

    in Database and File IO

    Posted

    QUOTE(tmot @ Oct 25 2007, 04:56 PM)

    ...the time it taks for writing data to the table is still 40-60ms. So, I now wonder, is this a normal case for you too? I mean, can one say that saving data to a MySQL-table over ODBC will take about 50ms in general?

    Maybe. Without knowing the specs on your computer, none of us can say what the throughput might be. I suggest you reread the suggestions in more detail. Writing once to the database might take 50ms. However, making a single call to a stored procedure that stores 1000 records might also take 50ms. I really think you should take a look at optimizing this from the database side. Write a stored procedure to write 1000 records and call it instead of the DB Tools Insert Data. Does the queue still grow unbounded? How long does it take to execute the stored procedure?

  22. MySQL and LabVIEW performance issues

    in Database and File IO

    Posted

    Usually the words "high-speed" and "database" don't go into the same sentence. I'd highly recommend splitting the control/deterministic code and writing to database code into separate loops. Use some sort of queuing/caching/data buffering mechanism to collect the data while the database writing code continues to write. Another possibility is to do a binary stream to disk with the data and then have a separate loop read that data and write it to the database.

    As others have pointed out, you can try to steamline your SQL code or write a stored procedure for writing the data to a database and you can design the tables to be more efficient. However, I think the best and quickest route is to separate the two operations and let each go as quickly as it can. The database writing will be slower, but at least it won't slow down the rest of your code.

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