configuration of IQ / number of samples for USRP2920

Similar Questions

• Units of the number of samples and rates for the DAQ Assistant units

  Hello

  I use the DAQ assistant for analog voltage of an input OR data acquisition card. What is the difference between the rate and the number of samples in the DAQ assistant and what are the units of the two?

  Thank you.

  The number of samples is how many discrete to measures. Rate (per second) is how fast to acquire the specified number of samples.

  If number of samples is 100 and the rate is 1000 samples per second, then the acquisition would take 0.1 second (100 / 1000).

  -AK2DM

• Large number of samples by FIFO - avoid the saturation of the buffer target

  My hardware is a PXI system, with a 7952R module FlexRio FPGA and a 14 bit 250 digitizer MECH NI5761. / s.

  Most of the posts I've seen facing some Mech acquisition rates. / s or less and the number of samples of a few 1000. In addition, my analog read as well as write FIFO is in a SCTL don't while loop.

  I want to buy say a 100000 samples each folder at the rate of 250 Mech. / s or more (millions of samples) at this rate.

  Here's the basic problem I condensed (I think that is). I use the example of the Acquisition of SingleSample as a test project.

  The FIFO DMA includes if the target and the host buffer. In practice, the maximum number of items that the target buffer can have is 32767.

  Now, once on the host, I request more samples to 32767, the memory stream buffer target above (overflow), the host THAT FIFO read node waits forever, until finally the time-out has been reached and the number of items remaining in the FIFO (I guess the host buffer) get enormously large (scales with the time, the read node waits (plus I Specifies the time-out is the largest the number gets).

  This is even if the depth of the FIFO is quite large (the host buffer is 5 x the number of samples per record).

  First of all, this suggests that the DMO transfer rate is too slow. However, this also happens if I acquire only 125 MECH. / s (take 2 samples of ns, which means 14 bits 8 x 125 Ms, so about 250 MB/s. This is well below the rate of transfer, as far as I know, so it should not be the reason. Or am I oversee something?

  The only solution I see is to limit the size of the records up. 32767 elements at a time.

  Someone at - it experience with large quantities of samples on a FPGA - digitizer using a FIFO for reading configuration?

  Just run the example CLIP unique sample vi and try to acquire 1000 samples, it will work. Try to acquire say 10000 samples and it will timeout as described above.

  Thank you!

  
  

• NEITHER 9212 - issues with sampling frequency, number of samples and size of buffer or slowness comes together with thermocouple module

  To begin with, I am very new to labview and unfortunately on that my first task is to build something rather complicated for a project that my company works. Fortunately it is especially followed rather than control critical processes.

  Currently, I have a cDAQ with modules, DI, AO, and TC.

  cDAQ-9133

  NEITHER 9472

  NEITHER 9421

  NEITHER 9263

  NEITHER 9205

  NEITHER 9212

  I'm currently running read-write for all 5 of these modules in parallel while loops and analog and digital inputs/outputs modules that all work as expected. Each loop requires 1 sample per channel through the wizard DAQmx etc for each module and I got can interact with all the asyncronosly inputs and outputs which at the moment is the goal. I can switch power switch for each module save memory, or if the need arrives later.

  My problem is that the module TC (NI 9212) when tilt on which allows the acquisition of sample 1 loop seems to take much, much longer to collect samples. I have played with different acquisition parameters and can seem to get a continuous flow of data when you use streaming samples, or even when specifying N-samples but I come in questions where the "application cannot catch up with the hardware.

  I tried to find an optimal number of samples/sampling, rate, etc I can get an update of temperature more than every 1 to 2 seconds, but if I set the number of samples that are high enough to apparently get a constant flow, what ends up happening waveform graphs seem to lag behind the actual data, and that's where I get errors. I only want 1 sample per channel per cycle anyway. Yet once, all the other modules in the cycle with less than 100ms delay between acquisitions but the module thermocouple ends up being 1-2 seconds. It's okay because in our application temperature should not rise/drop very quickly but its boring nonetheless.

  I have the acquisition set up for the same (NI 9212) thermocouple module was like my modules of analog and digital inputs (NI 9205 and NI 9421) take 1 sample every time the task is called so I'm having a hard time understand why do the same for the TC module introduced such a delay. Max sampling rate is supposed to be 95 samples/s/ch, so I guess that the delay must come from call the task over and over again in a loop.

  Synchronization and how you have configured the 9212?

  In the case of high resolution, it can reach 1.8 samples/s. see page 7 of the plug technique here for rates for the supported modes:

  http://www.NI.com/PDF/manuals/374389a.PDF

  -AK2DM

• Why 'Read a fixed number of samples' help with the error 200279?

  Hello world

  It is a question about a tip found in the explanations on the acquisition of data error-200279. This explanation it is said: '... ". reading a fixed number of samples instead of all available samples can fix this... »

  AFAIK the DAQ system buffer is a ring buffer, so we can consider having a writing position and a position of reading "in motion" along the ring. While the playback position is the position of writing, everything is brilliant. But if writing catch up reading, samples will be overwritten and therefore-> error-200279.

  So here's my question:

  I do not understand why a fixed amount of reading samples would help me with this error. I don't understand why other Councils (increase in the size of the buffer or the frequency of reading) would help me because they reduce the probability of the playback position being outrunned by the position of the writing.

  But if I read everything which is available, whenever I read the only way for the buffer fills would be that the time between two readings take more time than necessary fill the entire buffer.

  Or in other words to each reading I will read at least as many elements that it has been filled by writing since the last read, so the only way to fill the buffer would fill completely at once since the last reading.

  This should be a lot safer than reading a fixed amount, because in this case, I'd get a problem if I read it that fewer items than writing complete at the same time, regardless of the number of items that would be and no matter what the size of the size of the buffer that would be.

  What I understand here?

  Thanks and regards,

  Sebastian

  SBach wrote: this VI is a State Machine in queue, the reading part is made in the case of timeout and cases are used as initialization orders, stop and change the outside DAQ hardware.

  That I can't tell when these commands will trigger the time between two readings could not be set. If a strictly fixed amount of data could lead to a buffer to fill.

  Init command: you certainly don't have a running task.

  Stop: You stop the task, then doing here if you get overrun.

  Edit tasks: you will probably need to stop the task still before you can edit the task, but let's go back to not caring.

  The way I see it, the other commands must stop the task anyway.  If you can leave the timeout do its job and do not do a lot of extra stuff.

  And here are some alternatives:

  1. use a shift register to keep track of how long your wait time should be.  In the case of reading, make the deadline to be whatever it is that you are using.  In all other cases, only the 0 so that a read timeout must be performed immediately (once the queue is empty).

  2. When you do your check to 1.5 times the timeout, if there is too much data, queue a reading at the front of the queue so that playback will happen.  The idea is that you really want to keep the same stack sizes to keep the memory to be allocated.  So just to be read more often.

• Different output meter with a different number of samples

  I m using a calendar 6602 i/o Board or a MIO 6281. For controlling the distribution of our measures, I use different counters of two boards that have been triggered by a Digital Out for synchronization. The counters are made CO Pulse Time, implicit, digital synchronization triggered and the sample mode finished.

  Suppose I use two Ctr´s to map 6602. My problem is when you set the number of samples of only CTR for another value, then the second I m getting an error. The rest works perfectly, I can use different delays in starting, low or high times, only samples different amounts Don t work. It s without worrying if I use the Timing of e/s or Multi i/o Board.

  For example:

  _ _       _ _

  CTR 0 / 6602 _ |     |_ _|     |--> _ _ 2 samples

  _ _

  CTR 1 / 6602 _ |     |_ _

  Someone an idea or a tip?

  Hello

  two counters are used for a generation of fenite impulses. Please see the link below.

  Link:
  http://digital.NI.com/public.nsf/allkb/9D1780F448D10F4686257590007B15A8?OpenDocument

  For example, you can use Ctr0 and Ctr2.

  Concerning

  Rüdiger

• samples per channel and the number of samples per channel

  in my DAQ mode samples finished program, there are two screws: timing and read.vi DAQmx DAQmx.

  I have to set the parameter to "samples per channel" DAQmx timing.vi and 'number of samples per channel' on DAQmx read.vi... Is there a relationship between these two?

  My laser runs at 1 K Hz. I want to go to the wavelength, wait for a number of shooting lasers, read the data and move on to the next page...

  Thank you

  Lei

  In your case, the VI will acquire the lesser of either:

  The "samples per channel" that you have defined on the timing DAQmx VI

  -OR-

  The number of iterations of your for loop (N) times the 'number of samples per channel"that you have defined on the DAQmx read VI

  The "samples per Channel" VI DAQmx of timing for a finite acquisition dictates how many samples the DAQ hardware should acquire in it's onboard buffer before indicating that the acquisition is complete.  "The number of samples per Channel" on the read DAQmx VI dictates how many samples the DAQmx driver must return buffer on board the aircraft to your application.

  Let's say the "samples per channel" on the calendar DAQmx VI is set to 50.  Thus, the card will acquire 50 samples and place them in the edge of the buffer, then stops.  Suppose we have the 'number of samples per Channel"on the DAQmx reading VI the value 3 and what we call the VI in a loop For which runs 10 times.  Thus, every time the DAQmx lu VI is called, it will wait until there are at least 3 samples in the buffer, and then return these three.  We call the VI a total of 10 times, then we will answer 30 total samples.  Thus, the last 20 samples acquired the card remains in the buffer and are destroyed when the task is disabled.

  Now let's say that we increase the "number of samples per Channel" on our DAQmx Read VI at 10.  VI Read will wait until 10 or more samples are in the buffer, and then return these 10. Thus, we will be back all 50 samples map acquired by the 5th iteration of the loop For.  The 6th time we call him VI DAQmx Read it expires, because there will never be another 10 samples in the buffer, and the VI returns a warning.

  This clarifies things?

  The purpose of this behavior is to allow you to both set the total number of samples that the DAQ hardware will acquire and also control how much of these samples is returned whenever you call the DAQmx Read VI.

  Kind regards

• 9239 number of samples compared to rates

  Hi all

  I'm running a VI for the 9239.

  In it, I updated the sample clcok 2048.

  I then put the number of samples to 20480, IE rotate for 10 seconds.

  However, instead of the final point to be measured to 10s it measure to the 9.82992

  If it is set to 2048 samples the final time is 0.98256

  I realize that say, if I had a rate of 5 samples per second and one took five samples, I'd get the next 0,.2,.4,.6.8

  But if I had to wear it to 10 samples, I'd get

  0,.2,.4,.6,.8, 1, 1.2, 1.3, 1.4, 1.6, 1.8

  The important point here is that the offset remains the same

  In addition 1-1/2048 =.99951171875 pas.98256.

  Anyone know what is happening here?

  Sean

  Add to that,

  You made a very good point about the first sample being taken at t = 0.  Accounting for this, we get:

  20480 samples

  (20480 / 2083.33333) * (1-1/20480) = 9.82992

  2048 samples

  (2048 / 2083.33333) * (1-1/2048) = 0.98256

  What exactly gives the number you reported.

  Best regards

• What is the relationship with the sampling frequency and number of samples per channel?

  In my world, if I wanted to taste 10 seconds 10 Hz (100 s/ch), specify a rate of 10 and a number of samples of 100.  This would take 10 seconds to return data.  The task does not appear to behave this way.  No matter what rate and the number of samples, I chose, I spammed with data at 1 Hz or more.

  What I am doing wrong?

  This problem is resolved by making a request for telephone assistance.  It turns out that the minimum sampling frequency of the NI 9239 is 14xx s/s.  I don't know why there is a minimum sampling frequency, but now I have to go to the next question discussed at this link:

  http://forums.NI.com/T5/Multifunction-DAQ/how-can-I-read-gt-10x-samples-at-a-sample-rate-of-X/TD-p/2...

• How to abort Continuous Acquisition (which is set to acquire a constant number of samples per channel each iteration)?

  Hi all

  I would like to continuously acquire an input channel analog and, if necessary, be able to stop the acquisition as quickly as possible.

  I use a card NI USB-6289. I implemented a DAQmx (voltage) analog input task, set the clock sampling DAQmx 'continuous samples' and the rate required (IE 1000, which is 1 kHz). For the acquisition, I used a while loop with inside the DAQmx Read with Terminal 'number of samples per channel', wired (IE 1000). The while loop waits until 1000 samples are acquired and therefore continuously reads the channel in uniform batches of 1000 samples every second ticking. The while loop can be easily interrupted when the DAQmx has completed the acquisition of the lot being 1000 samples, but it takes the DAQmx finish their current task.

  My problem is how to stop the loop while the DAQmx Read lies in the middle to get 1000 samples WITHOUT delay all 1000 samples are received? Is it possible to interrupt the DAQmx Read?

  I could reduce "the number of samples per second", increasing the responsiveness of the while loop, but this is not the solution I prefer. I tried to destroy the task (outside the while loop), but that does not stop immediately the acquisition, Read DAQmx still finish acquire 1000 samples. I've included an example Subvi. When I was using a PCI card, I used a timed while loop with inside the DAQmx Read with Terminal 'number of samples per channel' wired-1 (= which means ' read everything in the buffer "). In this case, it was easy to stop the acquisition at any time: the timed, while the loop is abandoned and the acquisition has ceased immediately. But it does not work with an NI USB-6289 map (see thread http://forums.ni.com/ni/board/message?board.id=170&message.id=386509&query.id=438879#M386509) because of the different way the data are transferred to the PC.

  Thank you very much for your help!

  Have a great day,

  LucaQ

  Hi LucaQ,

  Your solutions are decrease of the number of samples, or record the time you want to stop and remove samples that have been acquired beyond this time. There is no other way to stop the actual reading out of the hardware store.

  Flash

• 2% USB 6361 C sampling for 8 channels

  What is the maximum rate for playback at the same time 8-channel USB 6361 map?

  I read the specification, and there is a line that says:

  Example Maximum rate... 2.00 MS/s single channel,
  1.00 MS/s multichannel (aggregate)

  When I tried to read 3 channels with sample rate 1 MECH. / s I have error: "Conversion ADC tried before the prior conversion was complete.
  I did some tests and it seems 500KS/s is maximum for 4 channels and 250 kech. / s max for 8.

  Am I missing something or is this how it works?

  aggregate refers to the total number of samples.

  This card uses a multiplexer to switch AD converter between the channels. SO not really simultaneous reading!

  One channel, no switching, fast 2 ms/s

  several channels: 500ns time to pass & set between channels, up to 1 ms/s left altogether, but you can read CH0, CH0, CH1 and CH2 that would give you 500kS/s CH0 and 250 kech. / s for CH1 & 2

• Total number of samples per channel

  Hello

  I was wondering if you can call a function that returns the total number of samples per channel read. I try to get a precise timestamp.

  I use DAQmx ANSI C developer environment.

  According to NOR:

  Option #1:

  Try and do exactly what the driver is doing.  This will require you to do exactly what you do in the displayed example.  Call time current system immediately before calling the DAQmx Read and subtract dt * x where x is the number of samples already acquired.  It will take you to know exactly how many samples were acquired.  It can be found by calling the Total property of the samples by chain acquired immediately before the DAQmx Read.  This is to introduce some points for innaccuracy.  For example, you're time system is already innaccurate to a certain amount.  In addition, it takes some time between the system times call, calling the total number of samples acquired and calling the DAQmx reading.  If 2 samples are acquired between the call to the time system and the total number of samples acquired, you could be shifted a few samples.  For the slower clock rates, you will have more precision.

  I try to attempet to program this solution, but cannot find the total number of samples per channel acquired property. If anyone can help me, your help will be very appreciated.

  Thank you for your help,

  Vladimir

  Hi Vladimir,.

  Here is the property you are looking for (as the C reference help):

  

  You will be able to get accurate relative timestamps, since we know that our acquisition is based on a sample with a certain dt clock.  The value of initial time must still come from the OS.

  Best regards

  John

• Is there a way to get the total number of samples to a TDMS file?

  I'm looking at the documentation for the function of properties Get TDMS and I see that it has a property: wf_samples which "represents the number of samples in the first data segment. Is it possible to get the number of samples in, say, the second segment of data? My goal is to get the number of samples in all segments of data for a single channel.

  To retrieve the total number of samples, I use the properties of 'NI_ChannelLength' to be linked to the function of TDMS properties get.

  The I64 outbut gives you the total number of samples of the selected channel.

  See attachment so useful

  Marco

• Why do I get a huge number of samples even with small flow and execution time

  I use the express Signal as my data acquisition software. NI9239 Daq is data acquisition system is my data acquisition equipment. Problem I have is, regardless of the data rate and the number of samples, I put, I get a lot of samples. for example I put the flow to 10 samples per second, and the number of samples to 600 (in continuous mode) I get more than 64000 samples where I should only get 600 samples total.  I tried to adjust the flow to 10 Hz and number of sasmples at 10, it gives me an error indicating that the data buffer overrun. Does anyone know a way around it?

  all responses are much appreciated.

  Hi odessy27,

  Maybe you can use the > Analog > step subset and resampling to resample the data at a lower sampling rate.

  Brad

• PCI-6070E: maximum number of samples (analog in) by Hz?

  In MAX and LV8.6 I have converted 1kS (analog in) at a rate of 1 kHz (the 6070E is estimated to be 1.25. MECH / s), therefore, seems OK.

  However, why conversion fails to 10kS to 100 Hz, just the same 1 MECH/s?

  Something to do with the maximum size of the buffer of an 6070E internal?

  If so, is Labview 8.6 fast enough to read and store 1 MECH. / s adjacent to the coast of the 6070E although 6070E data acquisition presents data of Labview 1000 pieces/s.

  I've run an AMD64 x 2 @ 6 GHz @ 4 GB RAM @ 2 TB HDD, must be fast enough.

  I certainly don't miss something, but what?

  In the data acquisition textbooks, I couldn't find lights on this topic.

  Thanks for any explanation.

  I'm having a hard time to understand what you are doing. You say "conversions fail to 10kS to 100 Hz, comes to be the same MECH/s 1." What is the actual sampling frequency you are using? Is - this samples 100/s? And you ask 10 k samples? If so, why are you doing it like that? If you want 10 k samples at this pace, you should probably ask 100 samples and make multiple readings. To get 10 k samples at a frequency of 100 hz, which would take 100 seconds, wouldn't you get anything until the 100 seconds is upward and probably the buffer overflow. Take 100 samples at a time and repeat 100 times would give you the same number of samples, but you get the data every second and not needing a such great buffer.