Tim_S

QUOTE (electrika @ Jul 9 2008, 03:01 PM) Yes, it is possible. However... you may wish to use a CSV file, which is fully compatible with Excel; this would be much easier to implement. This would involve opening a text file and writing out any header, then write out your values. CSV is pretty widely known and documented, so I won't go into that. Tim

QUOTE (Phil Duncan @ Jul 9 2008, 12:16 AM) Taking a quick look at the data sheet for the sensor, it appears to go down to 0 Hz, meaning you can measure a static load, however there is attenuation of -5% at 0.0003 Hz (effectively 0 Hz). You mentioned AC coupling... that will take out any static/DC signal you have; switching the settings to DC coupled will electrically allow you to measure a static load. I'm not familiar with the SCXI module to help you there. Hope that helps. Tim

QUOTE (KatieT @ Jul 1 2008, 12:31 AM) If you're looking to make the tabs different sizes (rather than the contents of each tab), then you can right click on the tab area of the tab control to change properties. The area you're looking for is: Advanced->Tab Size. There are options under there as to how the tabs appear. Tim

I just had a NI salesman call me. I asked if there was a way to put a note such that I wouldn't receive the calls anymore; he was able to add "a note into my file" so that I wouldn't receive such calls anymore (this time it was from creating a couple of "what-if" carts via the website). Tim

QUOTE (Ravi0709 @ Jun 21 2008, 01:41 PM) My initial thought is that your timebase (how fast you're updating the output) is faster than you're thinking. Without seeing code, any of us are grasping at straws, though. Tim

QUOTE (Doon @ Jun 20 2008, 10:19 AM) You got me curious enough to take a short gander at the DataGridView. You wouldn't happen to have a simple example of using it? Tim

QUOTE (Antoine @ Jun 19 2008, 05:56 AM) My first idea is to use FPGA based hardware. I'm guessing you're locked into the hardware you're using, though. My second though, and I've not investigated what's possible here, would be to leverage counter timers to as to provide a triggered reset line for, say, 100 msec (think of a off-after-delay relay). I'm assuming you have a PCI-6221 instead of a PCI-6227 (can't locate a 6227 on the website); the PCI-6221 doesn't have any counter/timers, so that's out. My third-and-least-favorite thought is to keep your loop timed to work at, oh, 20 to 60 Hz (166 msec ~= 6 Hz, so this is at least double to 10 times the rate) and programically re-arm the trigger. This option is entirely at the mercy of the operating system. Good luck. Tim

QUOTE (sasinew @ Jun 18 2008, 04:29 AM) It's certainly possible. ActiveX would give you control of Word directly. The report generation VIs should also be able to generate Word documents and print them.

QUOTE (djolivet @ Jun 16 2008, 10:37 AM) I have had some demo units of the PowerDNA cube some revisions back (about 2 years ago now). What I saw was a mixed bag. The PowerDNA appears to be a nice little rugged system, but it lacked the quantity of I/O points at the rates we needed and wasn't expandable (I understand they have been working on a synchronizing signal since). Data throughput was far better than what we have accomplished using TCP to a cRIO unit (some of that is our code, some of that is using standard TCP) and the people that visited us were very willing to work with us on getting what we needed. There were some software features we needed at the driver level which UEI added to a beta (most are now part of the standard distribution) driver; the driver was returning bogus A/D conversions along with the streaming data. Note that while the hardware/software/firmware didn't perform as we needed and had a blatent bug, UEI did get on a plane and visit us multiple times (manager and technical expert) while there was only a vague possibility of a sale (we've not paid them for any of this). The PowerDNA cube is a nice little (size-wise) expandable package. The cables UEI sells are nice, heavy duty with large metal thumb screws (versus the small plastic onces I've stripped skin off with from NI). The terminal blocks were a let down; they look like the NI TBX-96, but do not have common wires next to each other. For example, on NI's terminal blocks the pins are numbered (and I'm making this up) 68, 34, 16... which will correspond to channel 0 +, channel 0 -, shield, etc. The UEI terminal block had signal + on one screw terminal, signal - on another screw terminal and shield somewhere far away from everything else. The PowerDNA system does not appear to (moderately-)directly cable to any signal conditioning. This may not be an issue for you, but my customers expect 3B/5B modules. More discrete wiring is more chances for noise or much, much worse to get into the DAQ system (things don't work so well when you let the magic smoke out). Hope that helps you out. Tim

QUOTE (ned @ Jun 12 2008, 09:36 AM) I don't know if using VI server to run the containing VI will help; I expect you'll get the same results. As for detecting if the application has crashed, something to consider is a separate "watchdog application". This separate application regularly checks for your application or regularly receives a ping from your application (within a timeout). If the watchdog application detects your application went out to lunch, it can restart the monitored application. My VB counterparts use this to ensure that their critical RT applications stay running (funny what users will shut down when they perceive the system is running show).

QUOTE (Michael_Aivaliotis @ Jun 4 2008, 04:23 PM) I provide information to our quoting department what hardware to use, how much it will cost and how much software will cost, so I'm on NI's website regularly using their hardware system configuration tools (which are extremely handy). The call for (sometimes each) of the four what-if scenarios gets very annoying. QUOTE (Justin Goeres @ Jun 4 2008, 06:17 PM) Maybe there should be a checkbox in our ni.com profiles labeled Do not EVER make a follow-up call to me based on my browsing activites at ni.com. A profile flag would be an excellent idea.

QUOTE (Chelectro @ Jun 3 2008, 10:13 AM) If you are acquiring the signal as differential, then you will automatically get signal + with respect to signal -. If you can see both signals, then you are not acquiring a differential signal. Without looking up the channels, it sounds as if you have the wiring correct (the signal + should be connected to channel 0 and the signal - should be connected to channel 8). Tim

QUOTE (Mahmoud @ May 22 2008, 07:36 PM) My company builds ATE and lab equipment that includes engine cold test (which includes engine control module simulation for ignition events and cylinder cutout). You want something FPGA based and not a M-Series card. It may be possible to do what you need with a series of counter/timers; unfortunately, the 6250 card likely doesn't contain enough counters to decode TDC position much less create the timing signals you'll need. Tim

QUOTE (Dan Bookwalter @ May 22 2008, 09:07 AM) From what you've posted, I believe your best bet is to simplify your application to one VI (if possible) and then contact National Instruments technical support if you're still having issues. Tim

QUOTE (Mahmoud @ May 21 2008, 08:21 AM) What kind of task are you trying to perform? Based some assumptions of your rates (20 RPS and 360 ppr), you're not going to be able to respond to many things with Windows. There are alternative methods of DAQ if you're trying to make measurements with post-DAQ-analysis. Throw out your Windows routines and get something that is FPGA based (cRIO or the RIO boards work well) if you're trying to control engine components. QUOTE (Mahmoud @ May 21 2008, 04:04 PM) any information of how to do this ? Read the documentation for the board you are using; it's a matter of using the encoder as an external clock. Tim

QUOTE (gparant @ May 20 2008, 08:03 PM) Our local NI field support has copies of everything NI has put out since... well, I think they showed me a copy of LabVIEW 2. The Field Engineers are pretty good about handing out older versions of licenses of software you've purchased.

QUOTE (fuzzycontrolfreak @ May 18 2008, 01:41 AM) Setting the sampling rate as part of your data acquisition will set the dt based on the samping rate. QUOTE (fuzzycontrolfreak @ May 18 2008, 01:41 AM) This brings me to another scary thought, what if my DAQ is not able to sample at the specified sampling rate, due to computational time or whatsoever, will the FFT block assume samples are being fed at the specified 'dt' intervals, rather than actually referring to the actual time stamp of each sample?! The FFT should be ignoring the t0 and only use the dt and Y data of the waveform. If your analysis is not able to keep up, you'll have to look at alternative archetectures to acquire/analyze your data or look to optimize your data acquisition and analysis. Tim

QUOTE (Anders Björk @ May 16 2008, 07:23 AM) That's an interesting thought. I don't see anywhere in the documentation that would indicate such and the sample graphs of the express VI configuration show the X axis as frequency, not order. Thinking about it, I would expect a power spectrum to return an x-axis in Hz as that's how a power spectrum is defined mathmatically. The documentation for the express VI indicates it operates similarly to the FFT Power Spectrum. Replacing the express VI with the FFT power spectrum produces an error because the dx is 0. Correcting the dx with a constant (say 0.001), the VI runs correctly and produces a graph that displays the x-axis out to 490 Hz (slightly less than half the sampling rate). Tim

If you open up the express VI, the sample graph shows the bandwidth output goes to 0.5 Hz. I assume this is how the express VI works as it does not appear to have a means of setting the bandwidth and changing the sampling frequency and number of points of the input data does not change the output bandwidth (though this seems hard to believe). I would suggest nixing the express VI and using the power spectrum function. Tim

QUOTE (george seifert @ May 7 2008, 08:53 AM) I think the answer to this is the same as the answer to if a system is "real time"... it depends on your perspective. If your perspective is (sub-)nanoseconds, then no the VIs do not execute at the same time as a single processor can only perform one task at a time. If your perspective is in milliseconds, then the VIs execute simultaneously. The first caveat is that both VIs have to have all the data for their inputs at the same time so they start at the same time. If data flow is such that one VI obtains all of it's inputs before the other does then the first will start and can terminate before the second starts execution. The second caveat is that many PCs out there have more than one processor; this allows the PC to perform two (or more depending on the number of processors) tasks at the same time. Two subVIs that both have all of their data can start, execute and terminate at, quite literally, the same time down to the (sub-)nanosecond level on a dual processor PC. The assignment of threads to processors is at the mercy of the operating system, which could decide to run two threads on one processor because, say, someone assigned a database to run on the second processor exclusively. Tim

QUOTE (sara @ Apr 30 2008, 04:25 AM) Assuming that you have a board that outputs a logical "high" by default... One means we used to resolve this is to have one output that controlled an on-after-day physical relay. The relay would provide control power only after the PC had control of the outputs. I unfortunately forget the relay logic we used. Tim

QUOTE (Aristos Queue @ Apr 25 2008, 01:58 PM) Is there scrolling sheet music to go along with this?

QUOTE (reem @ Apr 27 2008, 03:44 PM) Without knowing what hardware you're using, I would suggest creating a task and then writing chunks of the output as needed. You would change the amplitude and frequency as you write out chunks, though I would recommend completing at least a half-cycle (waveform is a 0) to avoid discontinuities. Tim

QUOTE (SPM @ Apr 27 2008, 01:40 PM) LabVIEW is a programming language; Measurement Studio is a group of controls. You would have to pick a programming language (C/C++, VB, etc.) to use Measurement Studio in to create a front end. This point may resolve your issue. I've not used TestStand, but I have talked with a company who has created LabVIEW front ends for TestStand before; they did not seem to think it was difficult to do so and my little tests indicate that the two play nice together (though there is a learning curve there!). The dataflow paradigm is not an issue any more than the object-oriented nature of C++ is an issue compared to C. There are differences in thinking and programming and each has advantages and disadvantages; neither is better or worse. LabVIEW has an advantage for what you're talking about in that it is (in my opinion) easier to develop complex programs in and it is a NI product so there is one place to go for support and the finger-pointing that can occur is minimized. That being said, I worked with a man about 15 years ago who could whip out a complex Fortran program with GUI in a half-hour that suited his needs; to learn a new programming language and convert his libraries over was cost and time prohibitive.

QUOTE (farnoosh @ Apr 26 2008, 12:50 PM) Have you tried using the Web Publishing tool? It's located under Tools->Web Publishing Tool... (at least on LabVIEW 8.0). This will publish a VI's front panel to a webpage. I've not used it, but it sounds like what you're looking for. Tim