NI 5761 with low sampling rate

Hi, is it possible to change the NI 5761 sampling rate without programming FPGA? Thank you very much!

Hi, as mentioned above you can play with the sample rate by using an external Sample clock. Take a look at the picture attach for the general idea. Simply replace the Boolean buttons for digital input ports. I hope this helps
Alejandro | Academic Program Engineer | National Instruments
Attachments:
Capture.JPG ‏256 KB

Similar Messages

Low sample-rate measurements on the PCI-6115 DAQ card

I need to measure an analog signal at a sampling rate of a few tens to hundreds of Hz in sync with the rising edge of an external clock. I have a PCI-6115 DAQ card w/ Labview 6.1 and NI-DAQ 6.9.2. The PCI-6115 is a high speed card and has a minimum sample rate of 10 KS/s. Is there any way of implementing a low sampling rate measurement using the PCI-6115 in sync with an external clock?
Thanks in advance.

Kuldeep,
It is possible to do what you are describing above (in fact I don't think an external clock is required to do this), however, bear in mind that the reason for this minimum sampling frequency is due to the ADCs used on this high speed board. The ADCs used are pipelined ADCs, meaning that when a signal is digitized, it is digitized in distinct stages within the ADC (in the case of the 6115, I think there are 3 stages involved). Data is moved from one stage of the ADC to the next each time a sample clock pulse is recieved. If too much time elapses between these clock edges, the signal to be digitized can actually 'leak' off of the ADC. This can result in improper digitization, which can lead to less accurate measurements. So, while it is possible to mak
e the device sample below it's minimum rate, it may be advisable to sample faster than the rates required by your application, and either average multiple data points per measurement, or throw away extra points taken.
I hope this helps,
Dan

How to build a array with high sampling rates 1K

Hi All:
Now I am trying to develop a project with CRio.
But I am not sure how to build a array with high sampling rates signal, like >1K. (Sigle-point data)
Before, I would like to use "Build Arrary" and "Shift Register" to build a arrary, but I found it is not working for high sampling rates.
Is there anyother good way to build a data arrary for high sampling rates??
Thanks
Attachments:
Building_Array_high_rates.JPG ‏120 KB

Can't give a sample of the FPGA right now but here is a sample bit of RT code I recently used. I am acquiring data at 51,200 samples every second. I put the data in a FIFO on the FPGA side, then I read from that FIFO on the RT side and insert the data into a pre-initialized array using "Replace Array subset" NOT "Insert into array". I keep a count of the data I have read/inserted, and once I am at 51,200 samples, I know I have 1 full second of data. At this point, I add it to a queue which sends it to another loop to be processed. Also, I don't use the new index terminal in my subVI because I know I am always adding 6400 elements so I can just multiply my counter by 6400, but if you use the method described further down below , you will want to use the "new index" to return a value because you may not always read the same number of elements using that method.
The reason I use a timeout of 0 and a wait until next ms multiple is because if you use a timeout wired to the FIFO read node, it spins a loop in the background that polls for data, which rails your processor. Depending on what type of acquisition you are doing, you can also use the method of reading 0 elements, then using the "elements remaining" variable, to wire up another node as is shown below. This was not an option for me because of my programs architecture and needing chunks of 1 second data. Had I used this method it would have overcomplicated things if I read more elements then I had available in my 51,200 buffer.
Let me knwo if you have more qeustions
CLA, LabVIEW Versions 2010-2013
Attachments:
RT.PNG ‏36 KB
FIFO read.PNG ‏4 KB

How can I continuously streaming data to disk with 1MHz sampling rate with PCI 6110?

I can only save 3 seconds data with 1MHz sampling rate using PCI 6110. Is it possible to continuously save longer time data (say 1 minute)?
Many thanks

if the binary file is big the ASCII file is very very very big.
1 measurement is coded in a I16 => 2Bytes ( 4bit is not used 611X is 12bit
card)
if you use +/-1V range the quantum is (2 * 1V) / 4096 = 0.0004883V or 0.4883
mV you need to use 8 digits minimum.
And If your binary file is 1 Mo your ASCII file is 4 Mo.
You can use this VI for inpiration you need to add the translate I16 to DBl
to make a real value before saving.
For Help you can mail inthe newsGroup.
I'am a french user and my english is not good Sorry..
Fabien Palencia
Ingenieur d'etude ICMCB CNRS
"StephenZhou" a ?crit dans le message de news:
506500000005000000A5AF0000-1031838699000@exchange.ni.com...
> Hi, Fabien Palencia
>
> The program is great.
Do you happen to know how to convert the big
> binary file to ascii file? Thanks
[Attachment recup data I16.vi, see below]
Attachments:
recup_data_I16.vi ‏57 KB

Parallel acquire 2 signals with different sampling rate on 2 cards

Hi NI,
I have cDAQ-9178 and NI 9221, where sample rate is 10kHz and NI 9219, where I need sample rate about 10Hz, it's possible this confiruration for parallel acquire?
Thank you.
Neolker

Hi Neolker,
Do the tasks need to be synchronized or are totally independent tasks?
If the tasks are independent, than you basically have to create two different tasks, even in two different loops that will run with different sampling rate.
You can have them in the same loop the reading if you assure that the data are transfered in chunks to application memory according to tha sampling rate (Ex. for 10kS/s rate you can transfer data with 1kS chunks and for 10S/s rate with 1S chunk).
If you want to synchronize them, you will need a counter that will divde the sample clock from 9221 and route it to 9219.
Let me know if you need more help.
Best regards,
IR

Low sample rate with NI USB-6008

Hello,
We are working on a project collecting data from a hybrid rocket motor for
University research. We are using a NI USB-6008, which has a sample rate of
10kHz. We are using 3 channels and getting a sample rate of ~60 samples per
second. I have attached the VI. Is this slowed by software, or physical
computer computation speed? This sample rate needs to be much higher. Any help
is greatly appreciated.
- Theo
Attachments:
Hybrid DAQ_10.vi ‏73 KB

Hi Rocket 154,
You’ve already had some
great responses, but I just wanted to add a little bit. A great starting point
to writing good code would be the Getting Started with NI-DAQmx: Main Page,
as well as the shipping examples (In LabVIEW, Help » Find Examples) already
mentioned.
If you navigate a bit
through the links (Basic Programming with NI-DAQmx » Getting Started with NI-DAQmx
Programming in LabVIEW) you’ll end up with some great resources. I recommend Learn
10 Functions in NI-DAQmx and Handle 80% of your Data Acquisition Applications.
It will detail many of the functions you can use and give you a feel for proper
code style in LabVIEW.
I hope that helps.
Mark E.
Precision DC Product Support Engineer
National Instruments
Digital Multimeters (DMMs) and LCR Meters
Programmable Power Supplies and Source Measure Units

Counter Problem at low sampling rate

What I am trying to do is to count the input from the camera and generate the number of pulses depending on the delay and interval. At the rate of 33ms the program works perfectly but if the sampling rate is 150ms it generates 2 pulses at a time. Is there a better solution to my problem ? Am I doing anything wrong ? Is it a problem with the loop timing or acquisition timing? I have attached the program. What puzzles me is that it doesnt work if the rate is lower! Please HELP.
Thanks
p.s. I am very new to LabView so please excuse my ignorance.
Attachments:
CoolSnap.vi ‏142 KB

Hello sha33,
Thank you for getting back to me with more information. After looking through your code once more, I believe I have found the issue. Since this application is timed entirely in software, it is based on how quickly your operating system can run the program, and thus cycle through loop iterations. Since you have no Timing VIs in the program, this loop is running as fast as possible. Now, in the 33 ms case, you are getting a TTL edge a lot faster, so the DAQ assistant is updating its count faster as well. Lets say hypothetically that your loop is iterating at 60 ms. This means that every time you run through the loop your DAQ assistant will read the updated count value, and since you are counting every 33 ms, your count value will have updated.
Now let's look at your 150 ms TTL signal. This is significantly longer than the 33 ms signal in the previous case. Lets say hypothetically your loop is running on average at 60 ms again. This time, your edge will come in and the counter will increment, generating a pulse with the second DAQ assistant accordingly. Now your loop will run through again 60 ms later but your next edge on the 150 ms signal is still around 80-90 ms away. This means that your DAQ assistant will return the same count value as the last iteration, and once again a pulse will be generated.
Obviously the numbers I used for the loop iteration timing are hypothetical and entirely dependent on the operating system and its resources (i.e. it will run slower with an MP3 or Movie playing in the background). My suggestion would be to use a timing VI such as Wait Until Next ms Multiple to clock your loops more consistently. The goal would be to make sure that your loop is repeating faster than your counter is updating. Alternatively, you could account for the possibility of no counter input in your overall application to prevent a false positive.
Let me know if I can clarify any of the above information, or if you have any additional questions related to this issue.
Regards,
Chris Behnke
Sr. RF Engineer
High Frequency Measurements

Why LV 6.1 and Nidaq 6.9.3 can't acquire low sampling rate and high frame size

My platform is LV 6.1, Nidaq 6.9 on win98
Everytime i want to acquire data with sampling rate 6 Hz
and frame size 7200, it acquire just 2 or more data (under 10 data), never 7200 data.

Greetings,
I assume by "frame size" you are referring to the numbers of samples to acquire. Please launch the "Find Examples" browser in LabVIEW 6.1. Open the example "Acquire N Scans.vi." This VI has only 4 inputs. After setting your device and channel you will set number of scans to acquire to 7200 and your scan rate will be 6. Since you're only acquiring at 6Hz and wanting 7200 samples, this VI will take 20 minutes to run. At that point the graph will be updated with your data.
Regards,
Justin Britten
Applications Engineer
National Instruments

How to make EVERY new project open with 48k SAMPLE RATE?

Is there a way to set 48k as my sample rate default setting for all new projects I create or do I have to set it manually on a per project basis?
Thanks!

Bob Lyons wrote:
Might as well save 5 or 6 screen sets with your custom template. That's going to save you a lot of time setting up new projects.
Yes, good call! Anything to make life easier. This is why I'm moving towards doing all my projects in 48k. Since it's the standard for working with video,I figure why not just move all my projects up to it so I don't ever have to think about it again

Acquire 2 signals with different sampling rate?

Hello,
i am using first time labview signal express together with a NI pci 6251 & NI Scc 68 device.
There are 2 signals I wish to acquire over a 2 week time period. They should be saved in several tdms files. One is a dc Voltage.(sampling rate 100Hz) The second is voltage given by an acceleration Sensor. (sampling rate 4kHz)
When I try to acquire them I couldn't figure out how to set the sampling rate for each signal, only for all signals.
When I created two DAQmx assistant acquire tabs. An error occurs always: "the specified resource is reserved".
So my question is is it possible to do this?

hello markus_umd,
no, it is not possible to create different samplingrates for individual channels on one daq device.
if you want to record one channel slower, you must reduce the samples for that channel in your program.
if the channels have a common divisor, you could implement your task. you find more information here:
Sampling Different Channels at Different Rates with NI-DAQmx
kind regards,
robert h
NI germany

Problem with audio sample rate when exporting

I am having an issue with my audio sample rate. For some reason it is set at 8 khz by defualt when I am exporting. This was not an issue until the latest update (2 weeks ago). I'll try and give all the info I can up front. Also I tried customer support...that was a nightmare.
Ok the issue I am addressing is that the audio sample rate when exporting is at 8khz by default. Which to my knowledge has NO relevant use what so ever. Even when I set the file format to h.264 it insists on resetting to 8khz. Even if I manually set everything look at the render queue and click on output module again it changes the sample rate back to 8 khz automatically which I must adjust again. Why can it not just be set at 48000 like every other adobe product is and like it used to be two weeks ago. Does anybody have an answer?

This problem is addressed by the After Effects CC (12.2.1) bug-fix update, which is now available:
http://adobe.ly/AE_CC_1221
Note the part at the end of that page about a crucial update for the Creative Cloud desktop application, which addresses some severe problems with AME, Premiere Pro, and After Effects.

Lossless to lower sampling rate automatic?

I use Apple lossless for many of my imported songs. Will the iPod touch offer to lower the sampling rate on the fly? My shuffle used to do this.

Okay, I tried to bite the bullet and include lossless ripped music files in a synch. I did a SmartPlaylist and limited it to 10GB taken from my general Music Playlist, not played in 90 days. It is now synching a little over 5.6GB in lossless and the rest of the 10GB 128/256. All told 1,235 songs.
It is taking forever to sych. Pardon the pun, but this just about rips it I've got to downgrade the my lossless library which comes from CD's I own. I'm reducing the lossless files now. Hope this works without mucking up the sound too much.
Apple, please add the automatic conversion to a small file via iTunes like my iShuffle!!! Otherwise I've got to manage two music libraries. Any other Apple Lossless Touch users out there?

How To Lower Sample Rate

Is it possible to adjust the sample rate lower than the default when attempting to record an audio source?

44.1 is the lowest sample rate to record audio at in Logic. But put a Bit crusher plugin on the track and change the resolution there for more lo-fi sounds.
JG

High Latency with low frame rate

I'm getting 30 seconds of latency (between source video and
FME input window) when frame rate is set to 1.00 fps. With higher
frame rates, latency is very low.
Odd behavior: when switching from, say, 29.97 to 1.00 fps, I
see every frame (no frames are dropped), but they paint at only 1
per second (which means a large buffer is building somewhere).
After several seconds, the behavior switches to the expected 1 fps
(with all intervening frames dropped), but the whole thing is
delayed by roughly 30 seconds.
build: FME 2.5.0.2086
format: H.264 or VP6 (happens with both)
size: 352 x 240
bit rate: 200 Kbps
keyframe freq: 1 sec
Am I doing something wrong?

My encoding machine is a Gateway Pentium 4, 2 GHz with 1
GByte RAM, Windows XP Service Pack 2.
Video capture is done with a Pinnacle 510-USB peripheral,
Pinnacle driver 4.0.46.0.
Here's how I observe the problem: my input video is a color
bar pattern with burned-in time code. When I switch frame rates
from 29.97 fps to 1 fps, I see each and every frame appear in the
Media Encoder monitor window (as verified by looking at the
burned-in frame counter). However, only one 1 frame per second is
rendered. For example, I first see 01:00:00:01, then 1 second later
I see 01:00:00:02, then 1 second after that: 01:00:00:03, etc.
After several seconds, I then begin to see the burned-in time
code jumping in 1 second counts -- the expected behavior:
01:00:20:13, next second: 01:00:21:13, next second: 01:00:22:13,
etc.
The problem occurs when switching from any rate lower than my
source video rate of 29.97 fps, it's just that it's easier to
describe what happens at the lower 1 fps rate.

Lock-in amplifier, low sample rate options

Hello!
I would like to implement a lock-in amplifier in labview (version 8.5). I understand that there is a developer kit for the LIA available, and have checked it out; however, it is incompatible with my equipment.
I have a usb 1608fs card that I am using for for digital to analog conversion, which has a max sample rate of 16000 hz for two channels (signal and reference). The signal I am trying to lock in on is between 5 and 10 hz. The main contribution to the noise is 60Hz noise from the air, which shouldn't be a problem.
However, the lock-in amplifier by labview refuses to work at under 50KHz sample rate, so I am at an impasse. I could put one together myself, but I wanted to see if there were any options available to me; no point in reinventing the wheel.
Regards,
MB

Here it says the minimum rate is 50kHz. Sorry, but ther is no option to change that.
Also look at Lock-In Amplifier Startup Toolkit Compatibility with National Instruments Hardware.
Btw, there is no USB 1608fs card from NI.

NI 5761 with low sampling rate

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