Analog signal staircase help

Hello all,
I'm still new to LabVIEW, but I've played around enough to create a simple analog waveform generator. The signals produced appear staircased when displayed on an oscilloscope, but are smooth when I reread the signals into an analog input (as shown by the waveform graph). How can I change my program settings so that I can view this staircased signal?
I run LabVIEW 2010, and use a USB X Series Multifunction DAQ.
Thanks,
-Olivier
Solved!
Go to Solution.
Attachments:
Waveform Generator.vi ‏106 KB

Olivier,
Thank you for posting. I am a little unclear about what some of the front panel controls are in you're images, but I will explain the best that I can about what I believe is going on.
Take a look at the following images.
Generating a 1kHz sine wave:
Acquiring at 100kHz:
Acquiring at the Nyquist Frequency (2X the input signal's frequency):
What I am trying to demonstrate here is that you are only going to see a smooth signal if you are sampling fast enough. For instance, if you generate a 1kHz and sample at 2kHz, you will only see two samples per period. This will give you an accurate period and frequency, but nothing else. Because an analog to digital converter is used here, you must sample at a much faster rate to get a "smooth" signal. In my above 100kHz acquisition, you see that we are getting 100 samples per period which produces a much smoother waveform. I would suggest that you acquire a 5kHz signal at something on the order of 500kHz to see a smooth signal.
Let me know if you have further questions!
Regards,
Aaron
National Instruments

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Analog Signal to Digital a Primer

Many users have analog material sitting around, and they would like to get it into digital form, so that it can be edited. As this material is below SD (Standard Definition) quality, I will address the methods for digitizing it, so that it can be best edited in a DV Project. The output can be a DVD-Video, or other format, depending on what one wishes.
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Since a VHS tape deck does not have an A-D (Analog to Digital) processor, and also does not have a a digital signal Out, one needs something in between it, and the computer. That “something” serves two needs: mechanical connection of cables and the ability to convert the analog to digital for use in an NLE (Non Linear Editor). That “something” can be a digital video camera with pass-through capabilities, a device, called a “bridge,” or a capture card inserted into a bus slot in the computer. All three have pluses and minuses.
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Hunt
PS - also see this FAQ Entry for more detail.

the_wine_snob wrote:
Products, like the Dazzle lineup, just do not seem to work, or work well. I would avoid such.
Although I now have a Canopus ADVC300 I previously used a Magix 'Movies on DVD' USB device. I found the results from this to be particularly good and, to my ageing eyes, I see very little quality difference.
I think this is because Magix use their proprietary high quality codec (from their Pro products) to capture the footage. Like DV-AVI it runs around 10GB+ per hour. This can then, very simply, be exported to DV-AVI Type 2 for use in PRE. Note that there are some sound synchronisation issues with the 'out of the box' settings - but the fix is quick and I posted details to the Magix forum.
Would I revert if I could return my ADVC300 bridge? Probably not - the firewire connection and the PC seeing the box as a camcorder adds to ease of use. In fact I am pleased to have both. There are some things Magix does better than PRE7 (batch exporting each scene as an individual DV-AVI file being just one) and it has smart-rendering which is handy for quick clip splitting/exporting.
Cheers,
Neale
Insanity is hereditary, you get it from your children

Problem when combinning PWM signal and Analog signal TOGETHER!

Hello everybody,
first of all i have DAQmx 6212, and i need to run a small water pump (9V-16V) which needs to be driven by a PWM signal; also i have a motor (5V-13V) for a water valve that needs to be driven by a analog signal and it has a built in a force feedback potentiometer, i connected on the extremeties of this potentiometer +5V from the DAQmx and used the output voltage from the third extremety as a diagnose value for knowing the position of the motor.
my VI shows:
1. is a normal Counter output to create my PWMout signal.
2. is an analog input i use it as a PWMin to the LabVIEW to diagnose what is happenning in my water pump through the duty cycle and the frequency.
3. is an analog input from the third extremety of the potentiometer.
4. is an analog output which i have used as a power supply for the motor valve and i have used an AC/DC amplifier to aplify the signal from the DAQmx and drive the motor, between (3. and 4.) i have made a feedback with some calculations i had a P-controller to know the actual position of the motor valve.
My Problem:
when putting 1. and 2. in the same VI alone, i am getting a clean PWM in/out with no problems mentioned;
also when putting 3. and 4. in the same VI alone i can control the motor valve without any problems;
but when i put all these 4 together as found in the attached VI, i have a problem that the motor valve is running continously without stopping even if i change the valve position between 0 and 100 %, i should mention that i am seeing a normal PWM out/in signal on my oscilloscope, one other thing that if i delete one of (1. or 2.) and run the VI the motor valve is working fine without any problems.
so this my problem, if you can think of any solution please let me know.
thanks in advance for your help.
Regards,
Alosh
Solved!
Go to Solution.
Attachments:
pwm.out.in.analog.out.in.vi ‏45 KB

Dear nathand thanks for your reply,
i have ran the vi again and i am have error no 50103 from the (AI, number 3. ) but it is not displaying the error message, the VI keeps running without any error notification.
adding to that, i have tested the VI again today by placing (1. and 2.for the PWM inout) together in one VI and (3. and 4.for the motor valve) in another VI and ran them one after the other, i had another problem. if i turn the motor valve vi, the motor will run smoothly but in the pwm vi i will have a problem in which the AI did not read any value. also doing this vice versa by running the pwm vi first it will work perfect but the motor vi will have problem in reading the measured voltage in AI during this the motor will keep on running without stopping.
so i think now the problem is in AI (2. and 3.) readings they are interfering on each other but i am not discovering where is my problem...
Q: does the AI's seems well build or i can do it in an another way so to get over the interfering?
Regards,
Alosh

Analog signal smoothing

I have a LVDT analog signal that I need to plot to a waveform chart for a test that is running at 5hz. The signal is very choppy and unreadable. If I slow it down to say 1hz or less the plot looks like a nice sine wave, which is what I am looking for. What can I do to acheive this at 5hz. Thanks in advance for help and advice.

tavwtby wrote:
And why should I be converting the Dynamic Data to an array of doubles, I am only reading a sinbgle scalar. I would have to index the array anyway wouldn't I?
No you're not. Your DAQ Assistant is getting 1000 samples from 4 different channels. You are throwing away 999 samples from channel 0 and all of the other channels.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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SONY Handycam DCR-HC19E, Capable of Passing Digital Analog Signal?

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I don't know what settings on the camera, but this is the playthru checklist:
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Shane's Stock Answer #8:
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Analog signal from PXI

Hi everybody,
I have a problem: I cannot acquire 6 analog signals with a PXIe 8135 with 4MS/s. I use two boards with 4 MS/s, 16 bits and 8 Analog Inputs. I use a subVI of SAMPLE CLOCK for configuration with this parameters, Continuous SIGNAL, SAMPLE RATE = 4MS/s ( see attachment ). With one signal is ok, but with 2 signals, i have an overload Memory Message.
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Attachments:
acq_and_graph.zip ‏165 KB
acquire&loggdata.png ‏230 KB

Quickly looking through your code now, try removing the "Number of Samples analog". Since you are using Continuous Samples, you are just limiting the buffer and also limiting how many samples you can read at a time.
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There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

How to make a synchronous acquisition of two analog signals with a one channel DAQ ?

Hi !
It is the first time I use Labview. I have just made some easy VIs, and now, I do not know how to deal with my problem...
My problem : I have only one acquisition card (DAQ Ni 6034E) and I would like
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Thanks for your help !
Carline

Hi Carline,
A PCI-6034E is a low-cost board, which only has one Analog to Digital Converter (ADC).
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- http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/9379ea091c264b7c86256bc90082ca5d?OpenDocument.
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- http://digital.ni.com/public.nsf/websearch/4D1435DF82EF494186256D8A006DD6D4?OpenDocument.
- http://digital.ni.com/public.nsf/websearch/4D1435DF82EF494186256D8A006DD6D4?OpenDocument.
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Benjamin
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Synchronous acquisition 4 analog signal and independently count TTL impulse

Hello!
I'm have NI DAQ board PXI-6115. I have problem:
Need synchronous acquisition 4 analog signal and independently count TTL impulse. When value counter will, at example, 5000 acquisition must stop. I'm read program in LV 7.1 but have a problem. In HELP write:"You can create only one counter input channel at a time with this VI because a task can contain only one counter input channel. To read from multiple counters simultaneously, use a separate task for each counter". I make two different task, but error not disappear.
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Program VI with Front panel screen-shot in attach archive.
Message Edited by _Pavel_ on 05-23-2007 09:06 AM
Attachments:
Progr.zip ‏80 KB

Hey Pavel,
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http://ni.com/search
Attachments:
Progr.vi ‏58 KB

Is PCI-6036E suitable for me to send out analog signal to controll a device?

Hello
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Message Edited by Aneece on 04-09-2009 10:22 AM

The XXXXX's means it's recording sys-ex information from somewhere, probably from your Yamaha. It also means you're probably recording onto an audio instrument track, or a MIDI track, not an audio track.
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Focus on the "Getting Started" guide, and after you have a handle on that, try pumping audio in and out of the interfaces, one interface at a time.

Is there a VI availible that will allow one to interact with an analog signal

Hello all,
I am new to the sight and look forward to participating. I have a project that I’m working on and I would like to ask for your thoughts and direction if you’re willing. I have a few weeks left before completing an electronics program degree and Labview is one of the classes. The project I have chosen is to illustrate the differences between a micro controlled system and Labview controlled environment. I will be acquiring a signal through a ultra sonic distance sensor. The analog signal will be produced after which acquired through a SCB – 68 connector block and converted using the pci-mio-16E. The sensor operates at 40 kHz emitting a 5v pulse (burst) then falling to gnd for a short period followed by a 5v rise and staying high for a period of time waiting for the return of the frequency. This time period represents 3 inches to 27 ft in distance. I would like to interact with this signal through the distance period (portion) and output a string displaying a numeric value of the distance on the front panel obtained from an array built from different periods of the signal. I am not clear on what Labview function offers this type of control. I am hopeful in utilizing a vi or some type of trigger that allows me to build an array produced by some math functions. Any help would be appreciated.
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First thank you for your response, I will have an opportunity to make a capture tomorrow in class. I believe I have run across the waveform measurement VI in my searches and am sure it’s a very good choice. The trigger VI you suggest, going by the name, should be my ticket. Would you imagine a delay or decreasing time after the capture, allowing the trigger VI time to respond to an output configuration be required?
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How to introduce dead time in analog signals?

Hi, I'm new to LabVIEW and I want to introduce a dead time in the analog signals that I have attached in this post. The time difference varies, so I could not introduce a time delay in the signal
for instance, the attached waveform, i want the first signal to be seperated from the second signal. so i got 2 different signal at the end of the day for analysis. during the no signal time no signal is not recorded.
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Attachments:
Time delay.JPG ‏37 KB

Hi skydew,
It is possible to introduce a delay in an analog output. This is best done by specifying a trigger and then beginning the output when that trigger occurs.Below is a link to an example program developed for LabVIEW that waits a specified number of seconds and then triggers analog output to begin.I think this is what you mean as dead time.Take a look at this example and try to build from it for your code. If you have any further questions on this issue, let me know.
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Also see some links below:-
http://forums.ni.com/t5/LabVIEW/Finding-the-time-delay-between-two-signals/td-p/2125100
http://forums.ni.com/t5/LabVIEW/calculating-time-delay-between-two-signals-aquired-from-DAQ/td-p/849...
Thanks as kudos only

Synchronize Motion velocity with DAQ analog signal

Hi Everybody
I am acquiring analog signals using hw trigger and external clock with C and A signals of a 1024 counts TTL encoder.
Now I want to measure the rotation speed of a shaft. I have a Flex-Motion board with which I want to read the velocity (or the same encoder), but I don't know how to synchronize each scan of the analog signals with the velocity signal for that instant.
I can´t use RTSI bus because my Motion board doesn´t have RTSI connector.
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LabView 6i (v. 6.0.1.b3)
DAQ-Board: PCI-6023E, NI-DAQ 6.8.1, MAX 2.0
Motion board: PCI-FlexMotion-6C, NI-FlexMotion 5.0.1
Thanks a lot for your help.

Hi chia,
with the hardware configuration that you have, I think it´s not posible to synchronize both boards due to you cannot share the same clock source (not RTSI on the motion board).
http://zone.ni.com/devzone/conceptd.nsf/2d17d611efb58b22862567a9006ffe76/66e6f4ee7e0848d686256a55006...
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Regards
DiegoM.

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Hi, I am trying to "link" a couple of analog signals to a dital signal.
I have a torque transducer with a integral quadrature encoder. I am also monitoring a couple of other analog signals.
The 3 analog signals are being monitored through simultaneou sampling: 1Mhz for ~1sec
In these analog signals i am capturing certain events (peaks, etc).
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Ryan
Ryan
LV 7.1

Ryan,
Because we share the same name, I've created an example for you.
Basically, we're using the analog input sample clock to latch the
position of the encoder (connected to the counter). In a finite
acquisition, the exact number of samples you request are generated on
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tasks will be exactly synchronized. Please let me know if you have any
additional questions.
Good luck!
Ryan Verret
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Signal Generators
National Instruments
Attachments:
AI_Encoder_Sync.vi ‏99 KB

How should i do?when i use the sc2345 for analog signal acquired!

please help me！
I have to use the sc2345+NI6221 for analog signal acquired. but i don't have a analog input module such as SCC-AIXX.
So I want to pass the signal to the DAQ device. how should i do to connect the wire on the sc2345？
how can I use the sc2345 for a pass connector？
Thank you very much and look forward to your reply...
Solved!
Go to Solution.

What kind of signal do you want to acquire?
If it does not need any conditioning, then, you can connect the signal to 6221 with a terminal block such as SCB-68.
Best regards,
NISH AE Haiping.Fei

How do create an analog signal from a text or binary file?

I'm trying to output an analog signal from a file on an NI-DAQ 6251 card using labview 8.5. I've found the examples on building a waveform, but I'm stuck at how to read a text file and make a 1-D array to input my amplitudes into the buildwaveform.vi and I can't find any information on how to do so. Any help or direction is greatly appreciated.
thanks,
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Solved!
Go to Solution.

If all that you want in the file is the Y values, then a text file with a value on each line could be read. The Read From Spreadsheet File can be used. It will return a 2D that you can then use the index array function to get a column or if you select Transpose, the returned 1D array would be used.
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Analog signal staircase help

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