Multi-lane Express DAQ Assistant several sampling rate

Similar Questions

• Several sampling rate

  Hello

  I use DAQmx to acquire data in VB.NET (or c#) and I managed to create a task to capture data on several channels through of multiple modules plugged into a cDAQ chassis.

  However, I have a requirement to capture different channels at different sampling frequencies:

  1. Is it possible on different channels on the same module?
  2. Is it possible by using different sampling frequencies for the different modules?
  3. Or should I capture to a higher common sampling frequency and then decimate as appropriate?

  If possible, examples of code to create such a task would be much appreciated.

  TIA

  Hello Justin1,

  SEO of your questions:

  1. it is not currently possible on any module cDAQ.

  2. This is possible only if you have NOR cDAQ-9174 or material NOR cDAQ-9178, as these support different sampling frequencies.

  3. to taste several channels at different speeds, the recommended method is to try all channels at the higher rate you need and then get rid of the extra samples.

  Please take a look at the following link that you may find useful:

  http://digital.NI.com/public.nsf/allkb/96FD2F4685065C7686256F25006EE8DE

  Kind regards

  Fouad

  Technical sales engineer

• is daq bit resolution applied to the area defined in the daq assistant or well to the limits of physical blood of the daq hardware.

  Hello, this is my first post here,

  I've been wondering about this:

  When you configure a new daq with the daq Assistant, is the resolution applied to the voltage / number of entries you define, or is it a fixed value per volt by channel.

  For example:

  I have a 6015 usb data acquisition, it has 16 inputs analog, 16-bit resolution 250 kech. / s 09:50 volts.

  so is this as (2 ^ 16) / (16 * (-10-10)) = my resolution through volt?

  or that this has nothing to do with the amount of channels,

  If I want to measure more than 0 to 5 volts, my 16-bit apply from 0 to 5, or even more scale of data acquisition (which is 09:50 volts)

  Thank you

  Marco

  You will get full-resolution 16 bits on each channel regardless of the number of channels is configured.  Renault most are multi-plexed if your specification of sampling RATE in usually a global significance that you can only scan channels with a sampling frequency = MAX RATE / number of CHANNELS.  Also, most NI Renault have a Programmable Gain amplifier on the front-end server, so if you specify a range of voltage smaller in your task configuration the amplifier will automatically increase the gain to use most of the possible BIT ADC.  You see care device and for more details...

• Conversion task DAQ Assistant

  When I try to convert my DAQ Assistant tasks with a right click - Convert to task NOR-DAQmx I get a name and a scrolly input output with all the broken wires. Similarly, if I create a task in MAX and then use a constant for the task on the block diagram name I get the same result of entry scrolly. Am I missing a step here?

  Thank you

  Hi Mirabelle

  Glad to hear that you managed to solve the problem! In response to your questions:

  -L'information that read you about the creation of tasks in MAX is correct; It is possible to create a global task (an available screw a lot) in MAX. However, it is not necessary to create all of the tasks in MAX. As you think, if you use the task within a single VI, there is no need to create the task in MAX - in fact, it's probably easier just to create the task in the VI himself, either with screws of Express Assistant DAQ or DAQmx screw person on the range of functions located under e/s measurement > DAQmx - Data Acquisition.

  -When tasks change in MAX, it will not automatically be changed in LabVIEW. To make changes in LabVIEW, you will need to edit the task properties in LabVIEW, or remove the old task and replace it with the change.

  -I'm not sure what you mean by the question in your "P.S." to 100%, but I'll try my best to answer. Is there a specific example you speak? If you ask the use of screws DAQmx as DAQmx Virtual Channel Create, task control DAQmx and DAQmx Read etc., as shown in the examples of the expedition, then there are a few reasons to use those. Basically, screws of Express DAQ Assistant consist of a combination of the screw in the DAQmx - Acquisition of data from the function palette section. In general, screws of Express DAQ Assistant moving slower than the standard SIE DAQmx. It may be easier to debug the code when using standard screw, as it is obvious which task runs each section of the code. And finally, there are some limitations to the use of the DAQ Assistant, so while they may be easier to use in the short term, long term, I would recommend familiarize themselves with standard screws, because they make possible more complex tasks.

  I hope this helps! Feel free to let me know if you want to bring me anything, or if you have anything else that I can help you.

  Best regards

• 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.

• Consecutive calls to DAQ assistant

  Hello

  I'm working on something that is very probably simple.  Maybe the problems stem from a bad initial design choice.   The VI (and subVIs) are used at a voltage output, read another tension and react accordingly.

  First the error I get is "error-200547.

  Here's how the program works:

  1 MOVR.vi

  This generates two analog output signals, controlled by the same signal generator.  There is also a digital signal, but I don't think that's the problem.

  2 MTUL.vi (and MDTL.vi)

  These use MOVR and read another voltage.  Essentially, the voltage must be created until the limit is reached, and he decides to stop.

  These two work as expected on their own.

  3 IsoMeasure.vi

  This is where the problems occur.  Basically, this VI take MTUL and MDTL and makes a loop in a loop for, change the frequency of each increment.  The observed performance is MDTL will work and try to start MTUL.  It's when 'Error-200547' is thrown.  The error code appears to be understandable, but "autostart" isn't clear for me using the wizard.

  I would avoid using all daqMX code, but I will if I have to.  If that's the suggestion, a good example is that sort would be great.  If I can put the autostart Assistant, I guess it would help as well.

  Thanks for all the tracks.  I think it should work.

  Hi drevniok,.

  The reason why you get this error is that you try to restart your DAQ Assistant several times in your application. One important thing to note is that a task DAQmx configured and started only once each time the DAQ Assistant is called for the first time. Therefore, since you are stop and start the DAQ Assistant, in your application, the second time you call the wizard, it does not start the task. This is made more so by the fact that the function of writing in the DAQ Assistant DAQmx has his automatic starting of entry set to False.

  Using the DAQ Assistant for Analog Output returns an error-200547

  That being said, the DAQ Assistant is mainly used as a quick and easy to set up and use your DAQ hardware, however, it is a bit limited in functionality compared to the lower levels DAQmx live. This is a case that illustrates this limitation and therefore, I believe that the best solution this problem would be to use the DAQmx LabVIEW vis a lot shipping examples that can help you get started developing your application. These lie in you NEITHER example Finder under the menu help. "" The example I want to show you is the Regeneration.vi Clk - no Cont Gen Wfm - Int voltage under input and output material"DAQmx" analog generation "voltage.

  Is another resource, I want to tell you the getting started with NO-DAQmx: Homepage, which are a collection of tutorials online on DAQmx programming.

  I hope this helps.

• 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

• Question DAQ sample rate

  Hello

  I tried to understand how the 'number of samples' and 'rate' controls affect the frequency of sampling for the DAQ hardware. For example, say I want to acquire data from a sensor of pressure at a frequency of 10 Hz intuitively, I would think everything I do is on the desired sampling frequency, in this case 10 Hz control the 'frequency', try this, I know that's not true. I read that 'number of samples' affects the sample rate by setting a buffer value that must be reached before the VI will process the acquired data. So I also tried to set the "number of samples" to 1 and "rate" at 10, thinking this would have led to a sampling frequency of 10 Hz, and again, it is not. The only way I know to control the sampling frequency is using the wait function (ms), but then I always get buffer overflow errors.

  Can somone if you please explain to me the error in my thought process and also tell me the best way to control the sampling frequency? Is attached a simple VI, I am using to measure my actual sample rate and compare it to the sampling frequency that I am trying to achieve.

  The VI use the DAQ assistant to acquire data of pressure, inserts data into a table, and measure the size of the array. I'm then by dividing the size of the array by the elapsed time in seconds for the sample/s (I'm also dividing the number of iterations of the loop by seconds and using it as a comparison). I compare this value to my entries for the 'number of samples' and controls 'speed' in order to give a sense of the role they play in sampling rate. The VI also allows to choose to use the wait function (ms), as well, using this function is the only way I can control the actual sampling frequency, but then I always get buffer overflow errors. Any information would be helpful, thanks!

  What is the device that you are using? My guess is that whatever you have, it does not allow such a slow pace and is failing at its minimum.

• Question of sampling DAQ Assistant

  Hi all

  I have attached a VI that I used to record data from a few different voltage and the channels of the strain. All channels and sensors work perfectly and the VI reads data very well, but will be only newspaper for about 9 seconds. I found that the reason is that, within that period, the amount of updated read samples is reached. I also found that the reason for which is rather than on the statement sampling DAQ assistant 50 or 100 Hz it samples at a rate of about 1.6 kHz (0,000620 seconds). I have nothing seems to change the rate of that sample to so if anyone has any ideas it would be much appreciated!

  Thank you very much

  Andrew

  I think I can explain what is happening. In a previous post, the op mentions using a 9237. That has a sampling rate minimum of 1.63 kech. / s. The rate in the corresponding file.

  Andrew,

  Read the Manual would have answered your question.

• several channels in daq assistant

  Hi guys,.

  My first post on this forum, would appreciate some advice.

  I use labview 8.2 with PCI-6071E acq. card.

  I'm observing unexpected behavior when you try to read analog data on my card.

  If I define in the daq assistant, one way to read, everything is great, and the data is ready, as planned. I can see it in the preview window (explicit task)

  When I open the daq assistant.

  But, at the point where I have to add a channel more (from the same physical pci-6071e card), my measurements are totally fake - I get a strange signal...

  The sampling rate is more than enough (I enjoy with 64khz a 1 kHz signal arriving at one of my channels).

  What I'm missing here?

  Thanks for any advice you may have.

  Lenny

  With the generator of signals (output TTL) or the PCI-6071E AO the gsignla is NOT differentiated. Use one of the configurations of single entry completed.

  The Earth all unused inputs.

  Lynn

• DAQ Assistant: Reading of the samples that are no longer available

  I'm trying to use the DAQ Assistant to read some data, but I get "error 200279 occurred at DAQmc Read (analog 1-d Wfm NChan NSamp) .vi:2.» The error message suggests to increase the size of the buffer, most frequently read data or by specifying a fixed number of samples to read instead of reading all the available samples. My sync settings are as follows: continuous samples for the Mode of Acquisition, 1 K samples to read, 1 K Sample Rate (Hz). I'm curious to know what would be the best settings for this. If I set the mode to 1 sample (on request), would simply take a sample each time the loop works? Help, please.

  Thank you

  Brian

  Brian,

  Please post on the Forums of NOR.  Adnan a reason on why you get this error. If you use the sample on request, you will get only a value returned for each iteration of the loop. If you only need to try from time to time and there is no need to be very consistent, then this might work for your applications, but it depends on what type of application you have. How fast do you need taste?

• How to parse the input data of several channels simultaneously via an NI USB-6251 box by use of a single DAQ Assistant?

  I did separate VI for reading signals from several channels on a map of NI USB-6251.  I would like to combine these in a VI VI alone so that they can run that at the same time, however, there is an error if there is more that a single DAQ Assistant in the same--> error-50103 VI was held at DAQmx controls Task.vi:32 (the specified resource is reserved. The operation could not be performed as indicated.)

  All the inputs of channel must then be read in with a single DAQ Assistant, but all of the data on different channels are not separated.  Can save this data in a matrix or otherwise manageable which allow to facilitate the analysis of the data from the separate channel entries?

  I tried to view the data in a file of measures, but then when I tried InPort data, I could all the data I wanted.

  Hi AggieGirl,

  Good afternoon and I hope that your well today.

  First of all, you will not be able to have more than one DAQ Assistant by input analog or analog output task because the device has only one of each. So, you must have a DAQ task to HAVE and AO. (This is not the case for DIO static).

  There is far from split signals using the express VI - signal splitter.

  When you say you saved this file and it does not work, how it did not work? The Express VI - save a file of measures needed to manage multiple waveforms. Can send you your code & explain more about what was not OK on the file?

  

  Thank you

• Output DAQ savings at a lower sampling rate

  Hi all

  I'm relatively new to labview and all its features. The problem I've seen is that I don't know how to sample a continuous signal again. This is my problem, the assistant LabView DAQ samples continuously at 1 KHz so that the voltmeter is smooth as voltage changes. I don't want to have to record every 1000 data points every second even if in the .csv, so I tried many different ways to "resample" the data at a given rate of about 1-10 Hz.

  So far, I tried to use the loop of the timer, I don't know how well it works, and it didn't get me very far. I also tried to set all the values in an array of a specified size (with respect to the sample hz), take the index 0, delete it and begin to fill the table again. This kind of worked, but not at all how I wanted.

  Sorry that I can not provide photos or a vi like I changed it so many times he doesn't seem something like what I tried before.

  Assistance in this area would be very appreciated,

  See you soon

  Microtechno

  Use a shift to the filenme register.

  You didn't post your code so I don't know how you have the DAQ Assistant set up. You would get a writing all data to data acquisition whenever writing file is called. If you want only a scalar value of the DAQ Assistant, doing something as simple as calculating the average of the signal.

• NI 6552 Signal Express sampling rate

  I'm generating multiple signals for Signal Express. When I run them, some work well and others not, in other words, for some changes in sampling rate signals! Thera are two options in Signal Express: 1. read file waveform 2 sampling rate. to manually set the sampling frequency. In both cases, the rate is changed when I run the waveform of my 90 MHz to 100 MHz.

  Any ideas?

  Hello

  The internal clock on the 6552 is generated from 200 MHz time base; Is that you can generate the frequency of 200 MHz/N where N is from 2 to a large number which takes up to 47 Hz. The driver for the Board of Directors will force the neerest value, so if you swipe from 90 Mhz to 100 MHz frequency, you will get 100 MHz in all cases. There is more information about the synchronization on the specs here:

  http://digital.NI.com/manuals.nsf/WebSearch/E4C93B141B71ED93862573CC005E8EA1

  Once, you run your project, Signal Express should show you the corced value, you can use this to read the actual frequency generated.

  I hope this helps.

  Juan Carlos

• I use several DAQ assistant but it seems impossible...

  Hello world

  I'm on a project for some time.

  To summarize, I had 3 modules for the project: Anolog, digital, input resistance meter.

  My main program works, but now I have to connect with an excel file.

  I found an easy way of this solution, but now my problem is bigger. The fact is that I use my screws and screws with this how to link my data, but according to LabVIEW Sub, I can't, in the same program, do something in relation to 2 modules different. Obviously, each module works with a DAQ Assistant.

  To be more specific: I want to put the data from the 2 (thanks to the analogue of the module), and wire different sensors 1-> 0 or 0-> 1 (thanks to the digital module)

  And when I link 2 DAQ in the same file or 2 screws secondary who got 1 acquisition of data in entry of a measurement file, it does not work. The error that I can not launch the DAQ second after the first... so...

  I hope you understand my problem.

  You have a solution for this problem? Should I change a large part of my program to do this or is it just a small detail?

  Thank you in advance! I'm really disappointed-_ - I'm for several times... and I'm late for my project...

  Best regards.

  ML