Conflict to sample rate (specified real vs)

I use NI 9234 to acquire my sensor data using labVIEW 8.6. I have been using labView for only the past two weeks, so please bear with me as my knowledge is so fundamental. I'm reading several channels over time. My problem is when I finished my VI, I discovered the whenever I change my bit in VI code rate, she even more fast (several sampling rate than what I said).

I've never used a time base external with a data acquisition card, so it's a bit outside my field of knowledge. You may consult the manual to see if it's possible.

Personally, I wouldn't bother. If you want a lower sampling rate 1,652 kHz, you could always decimating up to a lower rate. For example, if you enjoy at 1,652 kHz and then take each sample 16, you would then end up with an effective 103,25 Hz sampling rate.

If you want to exactly 100 Hz you could make, because they suggest in the link and use the 'resample waveforms (continuous) .vi"to re - sample data.

Tags: NI Software

Similar Questions

  • sample rate real vs min sampling rate

    I'm sure it's an obvious answer, but here goes.

    I have a USB-5132 ' scope and using niScope horizontal configuration Timing.vi I put, among other things, the minimum sampling rate. In my case, I chose 20 MHz, which of course gives a sampling of 50 ns period.

    I use niScope reading (poly) .vi with the WDT variant to read waveform data.  I noticed something very strange - waveform limit testing throw error 1802 "signals have a dt of different values '-if I put a waveform components unclusterizer Get on the wire of waveform and looked at the value of dt of the wave." He told me that my dt is 40 ns, which of course is of 25 MHz. I also plead for only 2000 samples.

    So what causes this shift? Why the digitizer does not accept everything just my desired sampling frequency?

    Austin Walton wrote:

    Andy,

    The setting of minimum sampling frequency is the frequency at which digitized
    the samples are stored, expressed in samples per second. This setting is rounded
    up to and including the next legal collection that supports your device.  Ownership of the actual sampling rate calculates the actual sample used for the acquisition rate.

    Unless you specify another source of the clock, the digitizer uses an internal oscillator as clock source.  For the 5132, this oscillator is clocked at 50 Mhz.  When using the oscillator internal as the sample, the digitizer clock source can use versions split to the bottom of this clock, for certain sampling frequencies are not possible.

  • Specified sample rate clock works do not

    I hope that I was right to post on this forum. I have a problem that I had not previously in the acquisition of data on a chassis 9172 cDAQ using a 9234 for 2 analog inputs and a 9219 for four thermocouple inputs. The 9219 is obviously not ideal as it has a rate relatively low sample (and I have a 9213 on the way), so I'll have to use to HAVE. ADCTimingMode to isolate channels on this module for "high speed" mode if I can get an adequate sampling for my load. The question that arises is that no matter what I do to specify a sample rate, the actual sampling rate ends up being 1651,61 Hz, higher than the features of the 9219, if I get an error. I tried to use the DAQmx property node to set the calendar and the clock sampling VI but neither work. The only source that I can choose is on board, but when I check the source used is cDAQ1Mod1/AI/SampleClock, even if I get an error when I try to provide as a source of sample VI clock.

    As it is, my VI runs despite this error and seems to produce accurate data, but the original problem is with long testing I will have unnecessarily large data sets unless I start to decimate my other data, and the secondary problem, it's that I can't get the program to run when I try to incorporate my task of counter. In this case, the error ends the execution and he acquires no data.

    I have attached my VI under the task of counter (I'm on 8.5 and have the coming upgrade as well), but also an image of a simplified version of the VI only try to specify the settings of a channel of AI. I get the same result with it. I'm a bit of a loss here because I've never had this problem before, and it seems that there is something beyond rudimentary that I'm missing, so I would really appreciate any help anyone could provide. Thanks in advance.


  • Specific sampling rate?

    So maybe this is a stupid question, but I need to know because I train for a specific sound. Is there a way [to logic] to shoot/change of a certain frequency sampling rates. I can imitate the sound I'm looking for with a low pass filter, reverb and a distortion. But I don't want to 'emulate', this sound, I want to create. Then I can put my own effects and play with it like I want to. If I have to use a bunch of effects to make it sound like I want that also the addition of said effects remove the sound and sound horrible. as to where pulling the sampling frequency of the high frequency and no downs will make me THE noise that I need and always allow to add nice effects to make MY sound instead of someone else. I hope you know what I mean. Let me to you specific real once more. I want to pull or carry a certain frequency sampling rates for a sound under water. I don't want to use filters to make the sound. So can you please help me. I invited everyone locally on how to do it and nothing works. Also if this is not possible in the logic of tell me if there are third party plug ins or maybe even a different DAW that could do like komplete Kontrol or audacity.

    Effect under water

    See if this thread is helpful at all...

  • myRIO sampling rate

    I'm new to myRIO and use it to measure sine wave (0V to 5V) of up to 10 Hz 20 KHz. I also quickly transformed of Fourier (FFT) of the signal measured in real time.

    Sideways FPGA of things, I try to keep things pretty simple, just read 2 channels of AI (connector B: AI0 and AI1), therefore potentially able to read each HAVE 250 kech. / s (as the unit has a capacity of 500kS/s). Does that mean this program gets a two analog inputs data exactly every 4 microsecond? If this is not the case, how can I make sure that the data is acquired through a fixed sampling rate?

    I realized that we can add to the FFT in FPGA function, but I wanted to manipulte the acquired data of analog inputs before it is sent to the FFT, which I don't know how to do now. Can someone explain me how do the arithmetic data (muliplication, division and so) on the acquired data and analog inputs to reducde the 12-bit resolution 10-bit to program FPGAS.

    Later, I created a myRIO program to read analog data 2 FPGA program which continues to turn in timed loop. In the program myRIO, the timed loop is configured to 1 MHz clock source type by a delay of 25 microseconds.

    This configuration means that the loop runs exactly every 25 microsecond?

    When I set up the less than 10 micro second time, myRIO has stopped working. Why is it so?

    Is it because myRIO cannot run as fast as FPGA?

    It is advisable to make the FFT of myRIO side analog data or FPGA?

    When I tried to do FFT using the power spectrum of myRIO side, he asked for waveform data. What I acquire is data analog. How can I convert in waveform data?

    If I read in the forum for help, I couldn't have the full answer to my doubts

    Discussions at the Forum I did reference:

    http://forums.NI.com/T5/academic-hardware-products-Elvis/setting-tick-count-in-myRIO-FPGA-software/m...

    http://forums.NI.com/T5/academic-hardware-products-Elvis/myRIO-aggregate-sample-rate/m-p/2707061/HIG...

    A lot of good questions here, I will try to answer as much as I can so as to offer a bit of advice.

    First of all, if you are looking to acquire data at a very specific rate on the FPGA, you'll want to use the Timer VI.  You are also going to use a FIFO of DMA to transfer data of FPGA in real time. A node read-write using as you do now means you'll run out of samples, or read the sample even several times.  The link below is a very good tutorial on how to do what I described above.

    http://www.NI.com/Tutorial/4534/en/

    Later, I created a myRIO program to read analog data 2 FPGA program which continues to turn in timed loop. In the program myRIO, the timed loop is configured to 1 MHz clock source type by a delay of 25 microseconds.

    This configuration means that the loop runs exactly every 25 microsecond?

    When I set up the less than 10 micro second time, myRIO has stopped working. Why is it so?

    Is it because myRIO cannot run as fast as FPGA?

    In general, you should not run a timed loop much faster than 1 kHz.  Using timed inside loop knots, you can monitor the real rate of loop during execution to see if f you meet your needs of the moment.

    The portion of your myRIO RT is slower than an FPGA in the sense where it cannot manage the rates of lines 40 MHz (he makes up for it by being able to work with much better pictures) and it is important to remember that it is just a computer.  The advantage of a real-time operating system, is that you have more control on the Scheduler, not that he is faster (less jitter, not faster code). There is more good reading below.

    http://www.NI.com/white-paper/3938/en/

    It is advisable to make the FFT of myRIO side analog data or FPGA?

    When I tried to do FFT using the power spectrum of myRIO side, he asked for waveform data. What I acquire is data analog. How can I convert in waveform data?

    I would say that it is generally advisable to treat your FFT on the side FPGA as long as you have the resources available, but for many applications probably little matter ultimately.

  • PCI 5154 sampling rate

    Hello

    What is the sample rate max 5154 PCI for two channel inputs? The manual States the 2GS/s is for one channel only. So, am I not able to get a bandwidth of 1 GHz for the simultaneous measurement of two channels? Thank you!

    Hi gbhaha,

    First of all, TIS mode up to 20 GECH. / s using an ADC, while your real time sampling uses two converters a/n at the same time to a single channel.  Take a look at these diagrams that I linked in my first post for more details on this architects.

    About the difference in the bandwidth between the 5153 and 5154 - the 5153 has 500 MHz of bandwidth in its circuits, even when acquiring at faster sampling rates.  The 5154 1 GHz of bandwidth, this is why it is more expensive.

    Kind regards

  • Aggregate sampling rate

    Hello

    I'm looking at possible solutions for data acquisition. I use 4 or 5 entries analog and two digital inputs. During the analogue entered most of them will not need sampling extremely quick rate except for one who needs the least 100ks/s. I noticed solutions cost-effective have overalls sampling rate (eg. 250 ksps / s) which extends on all channels. For these products, such that the NOR-9205 compactRIO module, is possible to distribute unevenly sampling rate between channels (ie. could I give up 100ks/s for a single channel and spread the 150ks/s rest between the remaining channels in use)? Thanks in advance for any help,

    Adam

    Hello Adam,.

    To answer your question on the sharing of the sampling rate, it is not possible to have a single module different sampling frequencies, as described in this KB: here (http://forums.ni.com/t5/Multifunction-DAQ/Aggregate-sampling-rate-and-Multichannel-Scanning-Rate/td-....)

    In the case of the 9205 this module multiplexes between all channels (32 cases set up in single ended mode or 16 in differential) this means that the sampling rate of 250 kech. / s matches total on all channels.

    If you are using the differential mode then the samples per second on each channel will be 250 kech. / s divided by 16, IE 15KS/sec. However if you only specify 4 channels max sampling frequency will be 250 kech. / s divided by 4, IE 62.5 kech. / s.

    One way around this is to use 2 x 9205 in one of our new CompactDAQ chassis, which has 3 engines of timing to HAVE. This allows to set different timings in 3 different modules. What is described in this KB: here (http://digital.ni.com/public.nsf/allkb/E7036C1870F6605686257528007F7A72)

    I'm sorry of this reply took so long, and I hope the above information helps.

    Please do not hesitate to answer questions.

    If you want I could get one of our technical sales engineers to give you a call to discuss further with you data acquisition system?

    Kind regards

  • Save the high sampling rate data

    Hello!

    I use NI PXI-4462. (204.8kS, input analog 4 / s sampling frequency)

    I want to collect data from "load" (channel 1) and "acceleration sensor" (2nd, 3rd, 4th channel).

    I also want to save data to a text file.

    So I do a front pannel and block diagram. You can see in the attached file.

    The program works well in a low sampling rate.

    However, when I put up to 204800 s/s sample rate, the program gives me "error-200279".»

    I don't know what means this error, and I know why this happened in the high sampling rate.

    I want to know how I can fix it.

    Is there any problem in my diagram?

    Is it possible to save high sampling rate data?

    I really want to samplling more than 200000 s/s rate.

    I would appreciate if you can help me.

    Thank you.

    NH,

    You have provided excellent documentation.  So what has happened is that the amount of time it takes to run the other portion of the loop results in a number of samples to be taken is greater than the size of the buffer you provided (I don't know exactly what it is, but it will happen at high frequencies of sampling high) resulting in samples are crushed.  You might be best served in this case to take a loop of producer-consumer - have the loop you have acquire the data but then have an additional loop that processes the data in parallel with the acquisition. The data would be shipped from the producer to the consumer via a queue.  However, a caveat is that, if you have a queue that is infinitely deep and you start to fall behind, you will find at the sampling frequency, you specify that you will begin to use more and more memory.  In this case, you will need to find a way to optimise your calculations or allow acquisition with loss.

    I hope this helps.  Matt

  • DAQmxCfgSampClkTiming sampling rate for external sources

    I'm looking at the example of Synchronized_AIAO_Shared_Clock.c to http://zone.ni.com/devzone/cda/epd/p/id/2352 .  This example creates a string of tension that HAVE streams at 10 kHz, and then creates a tension AO channel that is bound to the sample clock HAVE to synchronize channels.  I use this example to understand the use of DAQmxCfgSampClkTiming here.  This is the corresponding code (comments are mine):

    Create a channel of tension HAVE will work continuously at 10 kHz

    DAQmxErrChk (DAQmxCreateTask("",&taskHandleRead));

    DAQmxErrChk (DAQmxCreateAIVoltageChan(taskHandleRead,"Dev7/ai1","",DAQmx_Val_Cfg_Default,-10.0,10.0,DAQmx_Val_Volts,NULL));

    DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandleRead,"",10000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000));

    Create a tension AO channel, and then attach the clock of the chain in tension of the AO for the sample clock HAVE
    DAQmxErrChk (DAQmxCreateTask("",&taskHandleWrite));
    DAQmxErrChk (DAQmxCreateAOVoltageChan(taskHandleWrite,"Dev7/ao0","",-10.0,10.0,DAQmx_Val_Volts,NULL));

    DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandleWrite,"ai/SampleClock",1000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000));

    .. So what I'm trying to understand here is how to interpret (1000.0) sampling rate argument in the second call to DAQmxCfgSampClkTiming, where the canal AO is related to "AI/sampleClock.  It seems to me that this argument must be meaningless, other than perhaps to determine the size of the buffer, since by definition this AO channel will clock on a sample of every time that AI/SampleClock rises.  Then maybe someone can help me understand how this argument is used...

    But in all cases, the docs say "If you use an external source for the sample clock, set this value to the maximum expected rate of the clock."  In this case, the clock is set up a few lines earlier at 10 kHz, so is not this 'evil' in the second call to DAQmxCfgSampClkTiming, a sampling rate of 1 kHz is specified (much less than the maximum rate of sample expected)?  What is the consequence of this?

    Thank you!

    -Dan

    Hey Dan, some big questions you've got.

    You pretty much put the nail on the head with your guesses. The size of the buffer is based on the resolution of data acquisition in combination with the sampling frequency that you specify. Think of it as an implicit in the size of the buffer declaration (but it is certainly an explicitly define that, if you wish).

    As for your second question, which relates to new back to the size of the buffer, except that this time it is for the use of an external clock source. Given that the material has no implicit way to know the frequency of clock of this external source, it asks you to specify explicitly the maximum frequency so it can create a buffer of the right scale size.

  • NI 5122 range Variable sampling rate

    Hello

    I use a digitizer card high-speed NI 5122 to acquire data and synchronize the sampling frequency of the frequency of the data card.  For example, my first set of data will have a frequency of 13.6 MHz so I would taste 13.6 MHz.  When I connect a signal 13.6 MHz to the CLK IN on the front panel of the card and write Labview code to taste at this rate (for the sample clock or reference clock), I get error message.  Anyone know if its possible to have a sampling rate variable really for this card?

    Thank you

    Steve

    Hi Steve,.

    I understand that you are using a digitizer high-speed 5122 and try to use an external sample clock. What kind of error messages received when you doing? In addition, how you set up the device to use this external clock?

    "" "" I would also like to point out that there is a very useful example program in the example Finder LabVIEW ('Help' to find examples) found in e/s material "Modular Instruments ' OR-SCOPE" features ""niScope Clocking.vi external EX' that allows the user to make a simple acquisition using an external clock source. To specify the source of external clock, rate and divisor, a knot of niScope property is used. You should be able to try this example and use the same method in your program. Hope this helps,

  • Sample rate Max USB-4065

    Currently, I am trying to log readings of DC voltage with an AA battery in an ASCII using LabVIEW 2009 of SingalExpress file and the USB-4065 digital multimeter (DMM). I have two stages:

    (1) acquisition of Signal > voltage DC using DMM

    -resolution 4.5 with 3.333333E the value-5 sampling period

    2) save in ASCII

    -The value to add to the file, delete the file after each race

    Faster reading, I can get is a data point written in the ASCII file every eighth of a second.

    Furthermore, I am new and software OR LabVIEW, the LabVIEW SignalExpress software I have is only for evaluation as it was included in the CD of the driver for the USB 4065 DMM.

    1. Max (30 000 samples per second) sampling rate is only achievable by a LabVIEW VI?

    2. Don't I have the wrong settings for DMM step?

    3. Is it because I haven't activated SignalExpress and am only using the evaluation version?

    Thanks in advance for any help!

    Hello Lukos,

    You are assuming that you need access to lower level functions in order to obtain the higher sampling rates. In order to get these speeds, we need to disable some settings that are not accessible via Signal Express. You can create a VI and then use a step VI call in Signal Express to stay in the same environment.

    Kind regards

    -Travis E

  • NI 9237 sampling rate

    Hi all

    I use a module 9237 for certain measures of the load. My experiences last over time and so I'm generating a lot of data due to the minimum sampling frequency.  I can't define an external time base so I can lower my sampling rate to something easier to manage?  Even just a sample rate of 500 s/s would make a huge difference.

    Thank you

    Hi cannisbellum,

    9237 specifications frequency range of minimum data (fs) using the internal master time base is 1,613 kech. / s and external use master timebase is 391 s/s. The simplest would be to sample at 2kS/s and decimate your data by 4. This can be done by using 'Decimate 1 table D' or ".vi Decimate (continuous).

    Rates valid for the NI 9233 OR 9234 sampling and NI 9237 - http://digital.ni.com/public.nsf/allkb/593CC07F76B1405A862570DE005F6836?OpenDocument

    Best,

    CARISA

  • DMM (NI 4070), how to correctly set AC Freq (bandwidth) by the sampling rate

    using a NI4070 multimeter and I see the max connection is 300 kHz by respect it.  But I don't understand how to set the min and max, acFrequency according to the sampling frequency or speed reading.

    6 1/2 digits resolution, the speed can vary from 0.25 s/s to 100 s/s and this range corresponds to a lower end on the connection (minimum acFreq) from 1 Hz to 400 Hz.

    (Q1a) - is the playback speed, controlled by the minimum setting of IviDmm_ConfigureACBandwidth?   or vice versa?

    Otherwise, I do not see how to control the rate of reading or the sampling frequency.   IviDmm_ConfigureMeasurement only allows you to control the range and resolution.

    (Q1b) - is there a way to directly control the sample rate (digitizer) or playback speed (dmm)?

    (T2) - the upper limit of the bandwidth of AC always seems to be at 300 kHz... is there still a reason to reduce this maximum value?

    (T3) - Finally, unlike the traditional niDmm function, the resolution via the IVI configuration should be passed as absolute value; does directly when number of digits and the beach?   For example if I want to 6 1/2 digit to 300V range, I guess that by the specifications that the resolution should be set at 0.001 V... followign, if I want 5 1/2 digits to 1V range, the resolution should be set to 0.00001 V?

    Hi Rjohnson,

    I'll try to answer your questions as best as I can:

    Q1A.  The ConfigurACBandwidth function is used by the driver OR DMM to calculate the good aperautre for the measure.  So yes, by adjusting your minimum frequency, you will affect your reading speed.

    Q1B.  Your reading rate will depend largely on your measuring cycle.  To get a fast measuring cycle, there are a few things that you can adjust.  You can programmatically control your time aperature, as well as your time to settle.

    Q2. I can't find a reason to change. This parameter is only used for error-checking and verifies that the value of
    This setting is less than the maximum frequency of the device.

    Q2B.  I think what you say is right, but I'll need to check on that - I'll let know you as soon as.

    Hope that helps.  "" "I would recommend checking the explanation of the Cycle of the DMM measurement in DMM help' devices ' NI 4070" DMM Measuments "DMM measurement Cycle.

    Take care!!

  • How to create a waveform from an array with arbitrary sampling rates

    Hi I know that sounds a little silly,

    Suppose I created a simple table of figures DBL with a structure For, Say size 16. now, I want to create a waveform DBL with these 16 numbers at an arbitrary sample rate. so if I use 1 kech. / s to the sampling frequency, I want to have a waveform with a duration of 16 milliseconds.

    Please help me, I need it too

    TNX

    Hello

    You must use the wave to build function as shown here: http://zone.ni.com/reference/en-XX/help/371361G-01/lvwave/build_waveform/ . Wire you your Board at the entrance Y and then wire the dt of entry in your sampling rate.

    -Zach

  • Sampling rate 9172 OR cDAQ

    I am using a cDAQ 9172 with modules NI 9219, NI 9264 and three NI 9211.  I'm looking to acquire signals out of the acquisition of data within a loop under continuous sampling.  My program works fine if I set the number of samples to read 1-2 Hz, but I need to go faster than that.  If I change the sampling rate, the loop is executed at this speed but sensors still read only in samples at 2 Hz and then duplicating over and over again.  I was wondering if it was possible to read on 1 sample at the time of the acquisition of data at a faster rate.  I know that the frequency of sampling on the sensors and data acquisition are much higher than that.  1 sample at the time of the Board of Directors has the limitatioins of being only able to run at 2 Hz?  Please let me know

    Thank you

    Craig

    Hi Craig,.

    I don't know exactly what you describe. Are you feeding the DAQmx Read output in an express VI? Or are you using the express VI DAQ Assistant for the analog input task?

    If you use the DAQ Assistant, you can set the ADC synchronization mode without changing your code:

    If not, use the 'Active channels (if subset)' property to control the subset of channels on which your VI defines AI. ADCTimingMode.

    For example, the following code snippet creates 8 virtual channels named myVoltage0 by myVoltage7 and sets HAVE them. ADCTimingMode on myVoltage4 of virtual channels through myVoltage7. These are in the cDAQ1Mod2/ai0 physical channels via cDAQ1Mod2/ai3:

    If you leave off of the entry "name" on the string to create VI, then the virtual channel names are the same as the names of physical channel, so it's the equivalent:

    And by the way, a right-click on the property and selecting "create > Constant ' context menu saves you from having to hardcode a number like 14712.

    Brad

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