Problème NI usb 6211, sample rate et sample to read

Bonjour,
je viens vers vous car je souhaite faire une acquisition continu d'un signal d'une entrée analogique. Sur cette entrée analogique est branchée un accéléromètre et un transducteur qui me renvoie donc une tension (120Mv/g) . J'ai donc réalisé à l'aide d'un exemple labview un programe. Cependant, celui-ci est très très long .. Lorsque je varie la tension d'entrée, cela prend plusieurs secondes avant d'afficher la valeur exact. Une erreur 200279 s'affiche lrosque les paramètres de sample read et sample rate ne correspondent pas... j'ai été voir sur le net sur ce lien :
http://digital.ni.com/public.nsf/allkb/AB7D4CA85967804586257380006F0E62
Mais rien n'y change. je vous laisse mon Vi en pièce jointe... cordialement
Attachments:
Test 1.vi ‏28 KB

Bonjour Geoff54,
Tu es sur le forum international donc si tu veux que quelqu'un te reponde tu devrais poser ta question en anglais.
Sinon il éxiste un forum francophone : French Forums
L'erreur que tu rencontres vient du fait que le buffer du PC se remplit avec les données que tu acquiers mais tu ne le vide pas assez vite et lorsque le buffer est complet il te renvoie l'erreur -200279.
Pour solutionner celà, il faut que tu viennes vider le buffer plus rapidement.
Tu peux faire celà en augmentant le "sample to read" à plus que 1000 ou bien en laissant la valeur par défaut qui est -1.
Bonne journée,
Valentin
Certified TestStand Architect
Certified LabVIEW Developer
National Instruments France
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NI USB 6211 : sample rate and sample read

Bonjour,
je viens vers vous car je souhaite faire une acquisition continu d'un signal d'une entrée analogique. Sur cette entrée analogique est branchée un accéléromètre et un transducteur qui me renvoie donc une tension (120Mv/g) . J'ai donc réalisé à l'aide d'un exemple labview un programe. Cependant, celui-ci est très très long .. Lorsque je varie la tension d'entrée, cela prend plusieurs secondes avant d'afficher la valeur exact. Une erreur 200279 s'affiche lrosque les paramètres de sample read et sample rate ne correspondent pas... j'ai été voir sur le net sur ce lien :
http://digital.ni.com/public.nsf/allkb/AB7D4CA85967804586257380006F0E62
Mais rien n'y change. je vous laisse mon Vi en pièce jointe... cordialement
Attachments:
Pièces jointes :
Test 1.vi ‏28 KB

Doublon et résolu ici
Valentin
Certified TestStand Architect
Certified LabVIEW Developer
National Instruments France
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How to measure frequency by USB 6211?

Dear all,
I'm using USB 6211 to measure the input analog voltage signal, then use a counter to yield the frequency. Please find the VI figure in the attachement.
The problem is the insteal of measure the right frequency, which is from 300Hz to 1000Hz. There is a lot of high frequency noise from thousand to milliion Hz. I think it pick up the high frequency harmonics. How to avoid it or use a more effective way to achieve the measurements.
Regards,
Alan
Attachments:
flow rate frequency measurement.JPG ‏43 KB

You have to suppress high frequencies on the analog side of your signal. You must set it to a frequency which is not higher than half of your aquisition rate. If you sample with 10 kHz your filter must have a cutoff frequency of max. 5 kHz. Otherwise you will see the signal mirrored at the half of the sample rate. A 6kHz signal will lead to a 4 kHz signal after the sampling.
Waldemar
Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
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How to send TTL output AND acquire AI voltage data using USB-6211

Hello,
I am relatively new to Labview, so please bear with me. I have a research application involving 2 pressure transducers and a high-speed camera. I wish to acquire analog voltage data from the 2 pressure transducers. However, at the start of the acquisition, I will need to send a single TTL output to trigger the camera. This TTL pulse must be sent out at exactly the same time that the AI acquisition begins, in order to ensure that my 2 pressure measurements and camera images are 'synchronized' in time.
Is this possible on the USB-6211 running with LabView 8.20? I currently have a fairly simple LabVIEW vi that uses a software trigger to start an AI acquisition - I have attached it with hopes that it may help anyone willing to assist me. I would prefer to be able to simply add something to it so that it will output a TTL pulse at the start of the acquisition.
Thank you in advance.
Regards, Larry
Message Edited by Larry_6211 on 12-19-2008 11:24 AM
Attachments:
USB6211_v1.vi ‏212 KB

Hi All,
I'd like to clear a few things up. First, you'll find that if you try to set the delay from ai start trigger and delay from ai sample clock to 0, you'll get an error. Due to hardware synchronization and delays, the min you can set is two. Note that when I say two, I am referring to two tick of the AI Sample clock timebase, which for most acquisitions is the 20MHz timebase. I modified a shipping example so you can play around with those delays if you want to - I find that exporting the signals and looking at them with a scope helps me visualize what is going on. The Manual has some good timing diagrams as well but it looks like you've already hit that. The defaults would give you a delay of 250ns from the start trigger - is this too high for your situation? What is an acceptable delay? I tend to think that "exactly the same time" is a measure of how precise rather than an absolute (think delays in cable length making a difference.)
With all that in mind, I see a few options:
Start your camera off of the AI start trigger (an internal signal) and just know it is 250 ns before your first convert.
Export the convert clock to use as a trigger. This assumes your camera can ignore the next set of convert clocks.
More complicated option: Internally you have an ai start trigger, sample clock and convert clock. From your start trigger to the first convert is 250ns but if you export your convert clock you're going to get future convert clocks as well. One option would be to generate a single triggered pulse using a counter (start with the Gen Dig Pulse-Dig Start.vi example) with the AI start trigger as the trigger for the counter, an initial delay of 250 ns, and a high time of whatever you want it to be. This should give you a singe pulse at very close to same time (on the order of path delays) as your first convert clock.
Hope this helps,
Andrew S
MIO DAQ Product Support Engineer
Getting Started with NI-DAQmx
Measurement Fundamentals
Attachments:
Acq&Graph Voltage-Int Clk.vi ‏37 KB

Can you record sound using a USB 6211 and convert the data to a .wav (or other sound) file?

Hello,
I am trying to build a system that will use a USB 6211 to record sounds from multiple electret microphones and then save the data as a .wav file or other sound file. I have already built my mics and hooked the mics up to the USB 6211; the DAQ device seems to do an adequate job recording the signal - I've recorded from 3 mics at a time at 11,025 Hz, although I don't know how good the signals are since I can't save them for playback after the fact, and they aren't going through my sound card. Ultimately, I would like to save the data as a multichannel audio file which I could then open in a program such as Audacity for further editing and analysis. Since Audacity can import a variety of sound files, my file format doesn't need to be .wav if another format would work better.
Any advice would be appreciated.
Thanks, Eric

If you are sampling all three simultaneously, your highest frequency recordable will be (11,025/2)/3, so about 1800Hz and that will pretty coarse (traditionally digital sound recording is at 44Ks/s at the low end). As to converting to a .wav, there are functions on the "Graphics and Sound" palette for saving waveforms to a .wav file.
Putnam
Certified LabVIEW Developer
Senior Test Engineer
Currently using LV 6.1-LabVIEW 2012, RT8.5
LabVIEW Champion

Trigger rearm time on USB 6211

I am using a USB 6211 to generate raster waveform and digital trigger to drive the galvanormeter mirror. I just want to send one cycle of waveform for every trigger pulse. The problem is that it seems like the USB 6211 trigger rearm speed is limited to about 20 Hz, which is quite low. Is this correct?
Any solution?
Attachments:
Triggering.png ‏76 KB

I might use the wrong word to explain it. What I mean by observing the behavior of the device when it was programmed as shown in the code is that no matter how fast my triggering clock was, there seem to be a certain period of time when the device did not accept any trigger pluse. That period of time was about 50 ms or about 20 Hz clock rate. The code worked as I expected it to be at trigger frequency less than 20 Hz. As soon as the clock speed pass 20 Hz, the extra pulse was not accepted.
One thing that I did to verify the 50 ms time limit was by sending 200 Hz of clockspeed and found that the one that close to 50 ms did trig the device.
Is there any example how to setup this device to surpass that trigger speed?
If not possible with the USB 6211, which DAQ device you would reccomend to achieve more than 100 Hz trigger speed, or even better for up to 200 Hz?
Thanks for your response : )

Externally controlled counter direction with USB-6211

I am using a USB-6211 and created a simple read counter application with the DAQ Assistant. It counts pulses (1 sample on demand) on Counter 0 (PFI0). When I set Direction to Externally Contolled it does not work properly. It counts random up and down. According to the manual my direction input line is Ctr 0 B (PFI1), but the level of this pin has no effect. What am I doing wrong?

Hello Steffan,
According to the following Knowledge Base you have cannot use the default settings wehn trying to externaly control the direction of the counter:
http://digital.ni.com/public.nsf/allkb/1A8818274130FA388625722E00760CC9?OpenDocument
Since these changes cannot be done in the DAQ assistant you have to use the DAQmx API to resolve this. I have attached a small example that does a simple event count on the source pin of counter 0 (which is also the A input of the counter). With a property node I have set the Counter Direction input terminal to PFI 1 (which is the B input). Now when the PFI 1 is low you will count up, when it is high you will count down.
hope this helps,
Regards,
RikP - National Instruments Applications Engineering
Message Edited by RikP on 06-05-2008 10:12 AM
Rik Prins, CLD
Applications Engineering Specialist Northern Europe, National Instruments
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Attachments:
Count Digital Events Up-Down USB-621x.vi ‏33 KB

USB 6211

Hi,
Can I use USB -6211 to be like a relay to turn ON and OFF the signal? The signal ON/OFF should happen instantly like a relay, no ramping.
/Kawsy

Hi mnk,
The USB-6211 will not quite work like a relay as there is no way of physical disconnecting its pins. However, if you simply wish to output signals ON (5V) and OFF (0V), you can do so by simply writing the appropriate value on the pins. Since this is an analog output, there will be some ramping at a very fine level. The specifications claim that we have a 5V/us slew rate, but this can vary depending on what load you connect this to. Examples on how to write to your analog output channels can be found in our LabView shipping examples.
Hardware Input and Output >> DAQmx >> Analog Generation >> Voltage >> Gen Voltage Update.vi.
I hope this helps,
S_Hong
S_Hong
National Instruments
Applications Engineer

Usage of DAQ USB-6211 with Sound and Vibration Measurement Suite

Hi,
Could I use DAQ USB-6211 with Sound and Vibration Measurement Suite ? All examples are based on 24-bit devices (usually with IEPE-on) such as NI 9234 or similar.
I don't need IEPE, 16 bit is sufficient for my dynamic range, could leave without simultaneous sampling - so 6211 (that I have) is OK for me.
Actually I'm interested in S&V Toolkit ( or Measurement Suite) as a tool with some specific Signal processing capabilities (for example, short-time FFT etc.)
Thanks in advance

Hi sgabr,
Yes, you can use the 6211 with some of the Sound and Vibration VIs, including most of the FFT functions. I know that's a little vague -- I don't have a list of which functions do or do not support 16-bit devices, but I did test it out on my system this afternoon. If there are specific functions or examples you'd like to know about, let me know, and I will try them out.
You also have the option to download the evaluation version of the Sound and Vibration Measurement Suite. That way, you can test drive it yourself!
Kyle B | Product Support Engineer | ni.com/support

How to output the digital clock and synchronization signal from the NI USB-6211

Hello,
I need to connect the NI USB-6211 to control a digital to analog convertor chip (AD5541). However, this chip requires three input signals :1) Clock input, 2) Logic input or a synchronization signal and 3) Signal Serial Data input (CS, SCLK, DIN).
how to output the digital clock and the synchronization signal from the NI USB-6211?

Hi SaberSaber,
You should be able to use the counters to generate a pulse train that could be used for clock and synch purposes.
Hope this helps. Let us know if you have more questions.
Dave C.
Applications Engineer
National Instruments

How to use voltage signals as input signals into USB-6211

Hello everyone,
I have a USB-6211 and a PDQ80A -quadrant photo detectot from thorlabs, i am trying to take three voltage signals from the PDQ80A into my PC using USB-6211 from NI. THese voltage signals are X,Y and sum (X+Y).
Looking forward to your reply.
Thanks in advance,
_Perseus

Technically, the question was in the title. But of course, the answer to that is... Connect them using WIRES. It's designed for voltage signals, just wire your cell outputs to whatever DAQ input channels you're going to read.
Using LabVIEW: 7.1.1, 8.5.1 & 2013

USB-6211 - Getting Error 50103 when attempting to use two counter method

I am using a USB-6211 and want to measure the speed of a motor by counting pulses coming back from sensors on the motor. Speed will vary from 0 to about 5k Hz.
My strategy is to use "Method 2" in the manual to measure using two counters. To do this I am attempting to generate pulses of known duration with Counter 0, route these pulses to the gate of Counter 1, send the motor pulses into the source of the counter1 and letting the counter determine and report the number of pulses that occur during the "gate time".
To get the pulse generator going at 8,333 Hz I do this:
AGniDAQmx_CreateTask(instrHandle,"TimingPulses, Task_Handle8)
AGniDAQmx_CreateCOPulseChanFreq(instrHandle, Task_Handle8,"Dev1/Ctr0","Out",DAQmx_Val_Hz,0,8.333,0.5)
AGniDAQmx_CfgImplicitTiming(instHandle, Task_Handle8, DAQmx_ValContStamps,1000)
AGniDAQmx_StartTask(instrHandle, Task_Handle8)
This works fine. (By the way, I do stop and clear the task before exiting.)
Now I add this code in a new task to try to use the Counter0 pulses to measure the input pulses with Counter1.
AGniDAQmx_CreateTask(instrHandle,"MotorPulses, Task_Handle5)
AGniDAQmx_CreateCIFreqChan(instrHandle,Task_Handle5,"Dev/ctr1",MotorPulses,0,10k,DAQmx_Val_Hz,DAQmx_Val_Rising,DAQmx_ValHighFreq2Ctr,0.12,10,"")
AGniDAQmx_ReadCounterScalarU32(instrHandle,Task_Handle5,10,E)
AGniDAQmx_ClearTask(instrHandle,Task_Handle5)
This function fails on the CreateCIFreqChan() call with an DAQMXError 50103.
Apparently Counter1 resources are being tied up by Counter0. Is this true?
Any suggestions?
Thanks,
-CBJohnson

Hi Mallori,
Thanks for the great reply message. I do appreciate your help.
Yes, I think you understand my application. The motor can turn from zero to about 5K RPM and one pulse is generated with each turn of the motor.
This application is using Agilent VEE but the statements are "C-like" so that's why I posted them like that. I can't "cut-and-paste" directly from the VEE statements and I have to type them.  I mis-typed the Implicit Timing statement. It was missing an "_". It should have been:
AGniDAQmx_CfgImplicitTiming(instrHandle,Task_Handle8,DAQmx_Val_ContStamps,1000)
I think I understand what you are saying about DAQmx_Val_HighFreq2Ctr using the resources from both counters That explains why I get the message about resources not being available.
I have tried to use Counter Method 1 and it *almost* worked.  A problem comes about when the motor speed is zero (stopped) and, since these motor pulses are being fed into the Gate of the counter, the zero value makes it simply time out. Increasing the timeout value to infinite (-1) makes the entire program hang. I need it to go on -- looking for other user input, reporting other data being collected, etc. If the counter is waiting for the Gate signal to rise to start counting and to drop to stop counting and do the calculation, it will not work since it just times out.  I went to this counter method (actually called counter method 3 in the DAQ manual) because then I am trying to generate the pulses of known period and send these pulses to the Gate.  Then I am feeding my pulses into the Source of the counter and letting it determine how many pulses occured during the "gate time". In this case, zero pulses during the "gate time" should be OK; it should simply report that zero pulses were detected and start counting again on the next rise of the Gate pulse.  I thought I could simpy adjust the length the "gate time" to measure my range of frequencies.
Make sense? Any way to do this with the two counters of the USB-6211?
Thanks, Mallori,
-Craig

How to make ROD426 connected to USB-6211 work in Labview

Hello
I have a rotary encoder type Hadenhein ROD426 connected to a USB-6211 I/O modul.
I need to make this work in Labview, so i can read the position for the rotary encoder by angle. I can't find anny tools in Labview that does this.
Does annyone have anny tips?
Gøran Steen

Gsteen,
There are some examples in LabVIEW's Example Finder (Help menu -> Find Examples...) that might help. Try Hardware Input and Output -> DAQmx -> Counter Measurements -> Position. These examples are usually a great place to start. I looked at "Meas Angular Position-Buffered-Finite-Ext Clk.vi" which looks like it may be of help to you. You can also limit the example finder to only find examples that pertain to your hardware (USB-6211) by configuring the "Hardware" dropdown in the lower left-hand corner of the example finder. If you are browsing, check the "Requirements" list in the lower right-hand to see if a particular example works with your DAQ.
-cb

DAQ Assistant: Clock Settings (Samples To Read, Rate) can affect signal readings?

Dear all,
I'm totally new to Labview, and recently I get confused with the equipment I'm dealing with.
Technical details:
The Labview version is 7.1; computer operate system is Windows XP;
The equipment has a NI PCI-6220 and a 68 Pin Connector Block to read signals from the equipment;
There are 4 channels in DAQ Assistant (2 pressure reading, 2 temperature reading);
For the first pressure reading, Signal Input Range from 4m to 20m Amps;
Clock Settings are Samples To Read = 5, Rate (Hz) = 20.
Description of the problem:
I use Labvew to monitor and record pressure readings and temperature readings. The Labview configuration was set up by my advisor several years ago. Recently, I found the pressure reading vibrated a lot; for example, 5.01 to 5.05 bar within a second. In order to get a stable pressure reading, my advisor suggested me to change "Clock Settings" in DAQ Assistant from Samples To Read = 5, Rate (Hz) = 20, to Samples To Read = 250, Rate (Hz) = 1000. In this case, she believed that since we increase sample numbers and sampling rate, we could have more data, and thus have stable pressure readings.
At first I could have very stable pressure reading. The last digit (0.01) did not change within 20 seconds. However, somehow after a day the pressure reading became unstable and even worse than previous. (pressure reading vibrates from 5.01 to 5.30 within a second)
This is not the worst case. We found that when we set Clock Settings: Samples To Read = 5, Rate (Hz) = 20, the pressure reading is about 8 bar. However, when we set Clock Settings: Samples To Read = 250, Rate (Hz) = 1000, the pressure reading is about 5 bar. In this case, we even don't know which pressure reading is correct.
Labview records current, and transforms it into pressure reading. Thus my advisor tried to monitor the current reading by Labview, and she found the current reading changed when she changed the Clock Settings. (0.004 Amps (5 bar) when Samples To Read = 5, Rate (Hz) = 20; 0.005 Amps (8 bar) when Samples To Read = 250, Rate (Hz) = 1000)
Since we only change the sample numbers and sampling rate, the average readings should still be similar. However, the reading are not similar. That is what confuses me.
My questions are, if Clock Settings in DAQ Assistant could affect signal readings? If so, how it could affect the signal readings? What is the effect of "Samples To Read" and "Rate (Hz)"? How to determine these parameters to get the true pressure readings?
Thank you very much for your help. Hope to have some feedbacks from you.
Best regards,
Cheng-Yu
Energy and Mineral Engineering
the Pennsylvania State University

A 6220 cannot read a current, it can only read a Voltage, so you'll probably have some (or should have) a resistor accros the voltage input. (normally 50 Ohm for a 0-20 mA signal).
My first step would be to measure this voltage with a multi-meter so you know what the actual voltage should be.
Then I would read that same voltage with MAX (measurement and automation explorer) to make sure you have the right value
Now about the changing of the voltage/current/pressure, how have you terminated the other signals? Have you provided a good earthing?
If you sample with a high frequency (1 kHz), perform an FFT on the acquired data, I can imagine a dominant 50 or 60 Hz (depends on where you live) in the signal that might cause your problem.
Ton
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Conflict between the saved data and the sampling rate and samples to read using PXI 6070e

Hello, I am using PXI 6070e to read an analog voltage. I was sampling at 6.6 MHz and the samples to read were 10. So, that means it should sample 10 points every 1.5 um. The x-axis of the graph on the control panel was showing ns and us scale, which I think because of the fast sampling and acquiring data. I use "write to measurement file" block to save the data. However, the data was saved every 0.4 second and as 35 points data at the beginning of each cycle (e.g. 35 points at 0.4 sec and 35 at 0.8 sec, and so on) and there was no data in between. Can anyone help me how there are 35 reading points every cycle? I could not find the relation between the sampling rate and samples to read, to 35 points every 0.4 second!
Another thing, do I need to add a filter after acquiring the data (after the DAQ assistant block)? Is there anti-aliasing filter is built in PXI 6070e?
Thanks for the help in advance,
Alaeddin

I'm not seeing anything that points to this issue. Your DAQ is set to continuous acquire. I'm not sure if this is really what you want because your DAQ buffer will keep overwriting. You probably just want to set to Read N Samples.
I'm not a fan of using the express VIs. And since you are writing to a TDMS file, I would use the Stream to TDMS option in DAQmx. If you use the LabVIEW Example Finder, search for "TDMS Log" for a list of some good examples.
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Problème NI usb 6211, sample rate et sample to read

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