Multiplexi​ng channels after the analog inputs of a DAQ Hardware
Hi,
I need to sample a 5KHz analog signal with 48 channels.
It's needed all these channels simultaneos.
I know there is not a DAQ hardwere at NI beyond 4 simultaneos channels.
How could I or NI solve this problem? Have NI an hardware that could be applied?
Greetings,
You are correct in that there are no simultaneous sampling boards that have more than 4 channels. Performing truely simultaneous sampling will ensure that there is virtually no interchannel delay and that the phase relationship between each signal is retained. If you use a regular Multifunction Input/Output DAQ board and some sort of signal conditioning, like SCXI, to increase your channel count, you will be performing a multiplexed operation. However, in most cases the interchannel delay is on the order of microseconds. If this is still too much for your application then I'm affraid the only answer is to get multiple Simultaneous Sample boards. You would want to trigger each board's acquisition to start at the exact same time. In order to
do this you could either use a PXI system or use PCI and leverage RTSI.
However, even with this suggestion you should keep in mind that most PCs only have 5 PCI slots, which will limit you to 5 * 4 = 20 channels. If you went with a PXI system and used the PXI-1006 chassis, which has 18 slots, then you could fill it with 12 PXI simultaneous sample cards.
PXI
http://sine.ni.com/apps/we/nioc.vp?cid=1525〈=US
NI PXI-1006
http://sine.ni.com/apps/we/nioc.vp?cid=4889〈=US
S Series Multifunction DAQ
http://sine.ni.com/apps/we/nioc.vp?cid=10834〈=US
Regards,
Justin Britten
Applications Engineer
National Instruments
Similar Messages
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Can the analog inputs be daisy chained to measure higher voltages?
Can the analog inputs of a PXI-6289 be connected in series to measure higher voltages than normally allowed at the analog inputs of the PXI-6289 (i.e. 10 VDC)? For example, let's say I wanted to measure 18 VDC using an analog input channel of the PXI-6289. I would then pick two AI channels and connect the positive of one to the negative of the other and then the two remaining leads would be placed across the 18 VDC. Resistors could also be placed across the 18 VDC to form a votage divide. One AI would measure the voltage across one resistor and the other AI would measure the voltage across the remaining resistor. I have tried this and the voltage measurements appear to loose accuracy. Thank you for your help.
Hello Rafi,
You may want to invest in a high voltage attenuator for signal conditioning prior to reading the signal. The documents below may also be helpful:
High Voltage and Isolated Measurements
http://zone.ni.com/devzone/cda/tut/p/id/10693
High-Voltage Measurements and Isolation
http://zone.ni.com/devzone/cda/tut/p/id/3410
Regards,
Roman Sandoval | National Instruments | RF Systems Engineer -
How can I syncronize the analog input?
The signal coming from the microphone input of the DSP module, displayed on Waveform Graph, is "slipping".
How can I syncronize the analog input?
Thank you!Ahh! You are doing this on the DSP itself. That would explain the Express VI problem, since you probably do not have floating point available. A simple level trigger is not hard to code using integer math. You can use the VIs I mentioned above as a guide (the algorithms should work well with integers as well as floating point) or just do it yourself. A possible algorithm for a positive going edge trigger is the following:
Search array until first point is less than level and second is greater than or equal to level (use In Range and Coerce to search).
Extract array subset from your data starting at the point you just found.
If you need a particular length of data and are continously acquiring, append data from the next scan onto your data until required length is met.
If you run into issues, let us know. Remember that shift registers are your friend.
This account is no longer active. Contact ShadesOfGray for current posts and information. -
Can we acquire the Analog input and Digital Input at
Can we acquire the Analog input and Digital Input at
the same time? My sensor data include Analog and
digital signals.Hi Chenchen,
It usually simplifies things greatly if you use analog inputs to monitor both the analog signals AND the digital signals.
If you abosulutely HAVE to use digital lines, then the answer is, DEPENDS....
With the correct hardware and depending on how fast you want to collect data and how closely the measurements have to be syncronized in time, it can be done.
But first, concider using analog inputs to monitor all signals.
If you need to move forward with both analog and digital acquisitions, then post a new quesion and give us details on the hardware you are using and the other details we will need to advise you.
Trying to help,
Ben
Ben Rayner
Certified LabVIEW Developer
www.DSAutomation.com
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction -
I am using the PCI-7344 to control my system. The analog inputs are connected to the output of my system while the analog outputs serve as feedback to the system. The system is a servo. I want to know what is the conversion between the voltage read at the input, to card counts, and finally to the voltage output to the system.
Carole,
If you are trying to do analog feedback with a servo motor, Chapter 14 of the manual talks about how to set up the torque feedback. Also linked below is a LabVIEW example of analog feedback.
Chapter 14
NI-Motion User Manual
Automatic Analog Feedback with FlexMotion example
A. Talley
National Instruments -
How do I use the analog input (ADC) to drive a motion profile in MAX
We are trying to use an anolog input signal from a DAQ card to control the motion contol axis. For now, we want the motor speed to follow a sinusoidal voltage waveform, and later on, we will be using a more complex velocity profile.
In order to accomplish this task, we have searched the user forum, and found information suggesting to operate the servo motor in 'slave' mode under the 'gearing' option. Therefore, we have set the Gear Master to 'ADC Channel-1', Mode set to 'absolute', Gear ratio 1:1, and provided the sinusoidal voltage (+/- 5V, 3 Hz) to the AIN1 connector on the MID-7654 controller. When using the 1-D Interacitve 'single axis' control panel, the motor runs at constant speed in one direction only. It does not react to the sinusoidal speed profile request as we expected.
How do we 'turn on' the 'slave' mode in MAX? Please talk us through the necessary steps and settings? Thanks.
StaffanStaffan,
you can configure and enablethe Gearing mode in MAX and it should be activated after saving the settings and initializing the board. In 1D-Interactive you can't use Gearing. For better flexibility I recommend not using MAX for configuring and enbling Gearing. You better should do this in your application.
In fact there is a perfect LabVIEW-example that ships with the NI-Motion driver (Master Analog Input - Slave Axis Gearing.vi)
I hope this helps,
Jochen Klier
National Instruments
Message Edited by Jochen on 10-02-2007 08:37 AM
Attachments:
gearing.jpg 162 KB -
How to making smooth the analog input.
I am trying to get an analog input from a device (torque meter). sending trough compactRIO and using NI 9025 analog module.
can get the signal, but too noisy. so how to make it smooth.
any suggestion what to use and what to do. pleaseactually I am trying to get analog input from a torque meter, the input is voltage,
and I am used the NI 9073 compact RIO with the NI 9025 analog module.
I am able to get the signal, but too much noise.
so, how to reduce that noise, just get torque signal,
what should I used,
any filter such band pass filter or what,
any suggestion.
I am still new with the compact RIO and labview, so hope any one expert can help me
thank you
regard
MSyafiq
Attachments:
measuring torque.pdf 165 KB -
How to combine the analog input and analog output vi's
Hi !
I have a perfectly running triggered analog input acquisition vi. I have a seperate vi for analog output that's running perfectly too. Can someone tell me how to combine these two operations so that I could get a vi that does simulataneous AI and AO without missing triggers. I have tried all the different kinds of configurations suggested by NI support but nothing seems to work. Can someone help ?
thanks,
Shiva
Attachments:
dac_good.vi 77 KB
adc_good_fw.vi 124 KBShiva;
I'm attaching a good Application Notes that shows how to synchronize multiple DAQ tasks, in Labview.
Hope this helps.
Filipe
Attachments:
Advanced_Sync_Techniques_for_DAQ.zip 166 KB -
Problem with the analog input acquisition in labview fpga 8.5.1 and CRIO
Hello all,
I am using NI CRIO 9104 RT controller with 9014 FPGA chassis.I am using an Analog input module 9205.My problem is with the acquisition.I am using a
function generator which generates some sine wave of -1 to 1 ,5hz to125khz sine signal and i have connected to 9205 in rse mode.In FPGA vi i had placed the I/O node and placed an indicator(data type FXP).If i connect the i/o node to a chart or graph,i am not able to see the output.?How this problem can bbe solved
Next i had placed a FIFO in DMA transfer mode of depth 1023 which will accept the U32 datatype,so i did some manipulation as mentioned in a tutorial.
Now in RT VI i am reading the same data from the buffer in U32 and doing the reverse manipulation i am able to view the data.Now the problem is ..if i am
increasing the frequency of the input signal,the data is completly lost ?How can i overcome this problem...
thanks in advance,
srikrishna.J
Analysis Engineer,
NeurofocusDifficult to see where is the problem ....
Be sure you are doing a good RT system by grabing reference design examples
Don't forget to specify the DMA FIFO size in the RT code
Doesn't matter the size of the DMA size under the FPGA project explorer.
Upload your code, You will get answers...
Mathieu -
What are the 4 analog inputs of my umi-7764 (on the analog input terminal block)
I would like to known what are and how connect the 4 analog inputs of the anolog input terminal block of my umi-7764. I am french, so if you want to answer in french, it will be easier for me .
Sébastien,
Selon la carte de contrôle d'axe que vous utilisez (7344, 7334 ou autre), vous pouvez disposer d'entrées analogique.
Si votre carte possède des lignes analogiques (voir la documentation de celle ci), cela signifie que vous pouvez les utiliser pour 2 choses:
1. Utiliser ces lignes analogiques pour le feedback (retour en position) de vos servo moteurs. Cela veut que vous travaillez avec un servo, et que vous êtes en boucle fermé. (Pour informations, un servomoteur peut aussi asservi avec un retour en position).
2. Si vous ne faites pas d'asservissement en tension ou que vous controliez un moteur pas à pas, alors ces lignes d'entrée analogique, peuvent être utilisées comme des lignes classiques. Pour les utilisez dans ce cas, vous devez cabler
votre signal sur l'UMI (qui n'est qu'une interface entre vos signaux et la carte) de la manière suivante:
- Le point chaud du signal sur "Analog Input X"
- Le point froid du signal sur "Analog Inout Ground"
De plus si votre carte de contrôle d'axe intègre des entrées analogiques, vous pouvez configurer leur gamme dans MAX (Measurement & Automation Explorer) le range de ces voies (+/-10, +/-5, 0-5 et 0-10 V).
(Comme l'UMI est un bloc générique, assurez vous bien que votre carte possède des entrées analogiques)
Finalement, pour lire le niveau de tension sur ces entrées, il existe dans le driver NI-MOTION, la fonction "Read ADC".
sur http://www.ni.com/manuals
vous trouverez la documentation de votre matériel.
A l'adresse ci dessous, vous trouverez de l'aide concernant la configuration de votre system motion dans max:
http://zone.ni.com/devzone/conceptd.nsf/webmain/081957EE013C7A4586256B92007818E0?opendocument
Raphael TILLET
Ingénieu
r Application
NI FRANCE
Cordialement,
Raphael T -
1 Analog Input using a DAQ card and would like to save the data into an excel file
As you may have realized, I am very new at using Labview 6.1. I have an analog voltage input that I would like to save in an Excel file as a 2D array (time, voltage). I was wondering if anyone knew a very simple way of doing this and could help me out. Thanks
There are a couple example program online and in LabVIEW that I think you’ll find useful. You might want to consider just writing out a tab-delimited spreadsheet file that Excel can read rather than writing it out to Excel directly as this requires learning ActiveX and Microsoft’s Common Object Model.
In LabVIEW, see the Write to Text File.vi in C:\Program Files\National Instruments\LabVIEW 7.1\examples\file\smplfile.llb. Writes simulated, timestamped data to a text file in ASCII format that can be read by spreadsheet applications.
Online, you can look at:
Stream Scaled Data (Voltages) to a Spreadsheet File
Chart Analog Data from File, Using the Cont Acq to Spreadsheet.vi Example
Hope this helps. Best of luck!
Kileen -
Why is the Analog Input data incorrect when VI is restarted?
In the attached Read Temp.vi I get correct data the first time it is run. Once stopped and then restarted the data values are incorrect. If I remove TS-1 from the I/O channel list then correct data is reported even when rerun. Why do I get incorrect data when I rerun and have TS-1 in the I/O channel list?
Attachments:
AI_Read_Anomaly.llb 42 KB
VPTS_Rev_2.daq 27 KBHello,
Which version of NI-DAQ are you using. try to upgrade it to version 6.9.2 available free from National Instruments website and see if it helps. It should.
Please tell me if it does not help.
Sincerely,
Sastry V
Applications Engineer
National Instruments -
Hi,
i wrote an App which loads several XML files and connects to
a JSP to get data from different locations.
On the startpage i choose a country and then all data is
loaded and shown.
Now my Problem:
That works fine for 2 times (no reload), on the 3rd time i
get the data but am unable to popup windows.
Then at the 4th try i don't get any data, not from a model or
the jsp .
If i reload my app it works again for 3 (4) times.
I hope the explaination is understandable and someone can
help me.
Thanx
MarianThis may take a while to track down (anyone else reading
this, feel free to chime in). I would write a new program that only
loads the XML files. Write the program so you have a button that
lets you reload that data. Then run it and see how many times you
can reload it. If it fails, then the problem is in how you are
loading up the XML. If it succeeds, write a program to connect to
your JSP and do the same thing - a button to reload the data.
Repeat the exercise.
You need to eliminate the possibilities. -
Size of the analog input signal
Hi,
very simple q how to protect my DAQ card from overvoltage. i mean, i produce some signal in my vi and i want to reduce it to max. say it 30V. how can i do this?
thanx in advance
vedranHi vedran,
I didn´t understand your question. Do you want to measure voltage and protect your card against the overvoltage or do you produce a signal with your DAQ card? Please tell me exactly what you want to do.
PatrickB
National Instruments Germany -
Determine analog input task trigger status
I am writing a basic analog input function, which will be triggered via a start trigger sent by another instrument. Is there a way to programmatically deteremine if the Analog Input task has been triggered? I would like to have a Boolean indicator that shows "True" after the Analog Input task is triggered, but I couldn't find out how. Does anyone have a suggestion? Thanks!
Is this a continuous acquisition?
I am not aware of a function querying the trigger state of a task. Nevertheless, i don't think this is necessary as you usually start reading right after starting the input task.
So in case a trigger is late, you will/should run in a time out error. Otherwise, you will get some data which is a clear indication that the task is running....
Norbert
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.
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