Read pressure signals using signalExpress

Hi, I don't have Pressure option under DAQMx Acquire -> Analog Input menu when I add a step to acquire pressure signals in SignalExpress 4.0. Anybody knows what extra module do I need to do so? Thanks. Cong.

Please post your question to the SignalExpress board. Very few users of it here on the LabVIEW board.

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Reading analog signal using DAQPad-6016

I'm trying to read an analog signal using DAQPad-6016. One input is ground, the other is Vdc. I can't get it to work in MAX and I'm confused becaue MAX only gives me an option for differential reading, but the pinouts don't give enough information on how to connect differentially. Is there a reference as well?
Solved!
Go to Solution.

Hello Bernadette,
This link should have everything you need to get set up correctly: http://www.ni.com/gettingstarted/setuphardware/dataacquisition/analogvoltage.htm
After you have a task set up, specifically see step 11 to verify the connections to the device.
I hope this helps!
Matthew R.
Applications Engineer
National Instruments

How do I view entire signal in SignalExpress Playback mode?

Problem: Playback only displaying 1 block of samples instead of ALL the samples collected when I click "Run".
Setup:
Monitor / Record:
DAQmx Acquire Analog Input (Acq Mode: Continuous, 1k samples @ 10kHz),
Create Analog Signal (DC Signal 100kS/s, 1000 sample block size),
DAQmx Generate Analog Output (N Samples).
Playback: Same steps as Monitor / Record, except DAQmx Generate Analog Output is Continuous Samples 1k samples at 10kHz.
I have dragged my data from within the Logs folder per Help Documentation Instructions "5. Play Back the Data"
All of the data is successfully written to a TDMS file and converted to ASCII. How to I view the entire length in Playback?
Using: LabVIEW SignalExpress v2.5.1 Lite, NI USB-6221
Solved!
Go to Solution.

Hi barkeram,
Something you could do in the Playback mode is change the "Playback block configuration" in the "Playback Configurations" View to see and manipulate the entire data. For example, my default block size was 100 samples and my entire data contains 2800 samples (as shown by the number of iterations = 28).
I can change that to be Block Size = 2800 samples (which is my entire data) in which case I will have only one iteration. My data view will now show all my data rather than just a block.
You don't have to know before hand how much data the log file contains. Just multiply the default block size and number of iterations (when you select playback) to get the new block size and enter it in the Block Size field.
Message Edited by Nitin T on 04-14-2009 05:43 PM
Message Edited by Nitin T on 04-14-2009 05:45 PM
Attachments:
original.jpg ‏15 KB
modified.jpg ‏14 KB

How to generate a chirp(linear FM) signal using dds theory in LabVIEW FPGA.

how to generate a chirp(linear FM) signal using dds theory in LabVIEW FPGA.
attachment:a sine signal using dds theory. Hope to get some help. Thanks!
Attachments:
FPGA DDS SineGen IP.vi ‏42 KB

you need to increment the "accumulator increment" during the duration of the chirp. the "accumulator increment" controls the frequency of the DDS cycle. by increasing it's value, you are increasing the frequency. the math for increment values follows the same math as determining the frequency to increment value.
Stu McFarlane
Viewpoint Systems, Inc.

Can you monitor signals using frame api on a PDA?

Hi all
I'm pretty new to LV all together, but I'm working on writing a program to monitor information off our CAN network, like oil pump speed, water temp, batt voltage, etc. Is there a way to monitor these signals using the frame api, opposed to channel api, and display them continuously on a gauge/meter? Since I'm using PDA module, I have to use the frame api, and not channel. Frame api seems a little more vague to me than channel api. Any advice or tips are welcome.
Also on a side note, I copied/pasted a tab that i changed the background color to yellow from a windows targeted program to a PocketPC one. The tabs stayed yellow when I built and transfered the .exe to the pda, but i don't have any control now on its color because PDA module doesn't have Property Nodes. Every now and then, the tabs will go to default grey, and i have to undo the changes to get it back to yellow. Is there some way to control the color? I don't think the Change Control Color works in this case.
Thanks ahead for any comments and advice.

....By the way, i'm using a PCMCIA-CAN/2 (HS) card on a PDA running WinCE5.0 and soon to be one running WinCE4.2...

How can I output frequency readings of my signals using FFT?

Hi there, I need help in regard to the topic stated.
Currently I have accquired a sine wave with frequency that vary, using one of the accquistion card by NI. I had converted it to a digital signal so that labview can read it. Now, I will like labview to output the measurement of the frequency.
For example : sine wave of 5KHZ is accquire , labview will use FFT to convert time domain to frequency domain, and then output the frequency of the sine wave, in the case, 5KHZ.
What function block should I be using? I had explored the function blocks of all FFT. Most of them output either real FFT, complex FFT, magniture or phase. But none of them output the reading of the frequency.
Maybe I had missed out some function block, so how do I go about output a frequency reading after using FFT?
Thanks a lot in advance.

After Converting your signal from time domain to frequency domain, u cant expect there is only one frequency component,they should have different frequency components according to your input signal.Use extract single tone information to get the output reading of the frequency.
Balaji PK (CLA)
Ever tried. Ever failed. No matter. Try again. Fail again. Fail better
Don't forget Kudos for Good Answers, and Mark a solution if your problem is solved.
Attachments:
Detect Freq.vi ‏15 KB

Can I boost the DSL signal using my 1st Generation Airport Extreme or Express? Also, can I get wireless printing?

Can I boost the DSL signal using my 1st Generation Airport Extreme or Express?
I just moved into a house where they have ATT DSL and it is really slow in my room. I am hoping that I don't have to purchase a booster and I might be able to use my Airport Extreme or Express to boost it. I don't think they want my Extreme as their router, though. They are PC.
I am also hoping that I can set up a wireless printing situation in my room using the Express or Extreme.
I am running 10.4.11 on my old MacBook Pro laptop, 10.5.something on my old desktop (MacMini).
Thanks for any help ahead of time,
Carole

Can I boost the DSL signal using my 1st Generation Airport Extreme or Express?
I just moved into a house where they have ATT DSL and it is really slow in my room. I am hoping that I don't have to purchase a booster and I might be able to use my Airport Extreme or Express to boost it.
Unfortunately, this won't work especially if you want the connection between the routers to be wireless. The two are just not compatible for configuring an extended network. However, it could work if you can have them interconnected by wire. In that case, you could configure them into a roaming network.
I don't think they want my Extreme as their router, though. They are PC.
This shouldn't be an issue as the AirPorts support wireless clients regardless of which operating system they are running.

Measure rpm and PWM signals using digital input of NI9401 module

Hi, is there a simple way how measure rpm (to 5000 rpm) and PWM (about f=3kHz) signals using digital input of NI9401 (ultrahigh-speed digital I/O) module plugged in NI 9172 ? I will wellcome any suggestions and VI examples (bether still). I'm begginer using LView 8.2. I apologize for my poor English. Many thanks.

Hi CUA,
Since you have already the right tools, you just need to get started with the software. The NI-9401 will give you access to the counters that are inside the cDAQ chassis 9172.
You need to place the module in slots 5 or 6. You can read in how they work and how to configure them in the counters section of the user guide found here.
Now to measure rpm, you can either measure the period of the signal (seconds) and multiply by 60 to have minutes and the number of ticks per revolution. You can find a shipped example to read period called “Meas Dig Freq-Buffered-Cont-Large Range 2 Ctr.vi” found under Hardware Input and Output » DAQmx » Counter Mesurements
To measure PWM, it is similar procedure and you can read the semiperiod (high time or low time). There is also a shipped example called “Meas Semi-Period.vi” found under the same location.
There is great information for these kind of task at this page or just post back if you need to.
Hope this helps.
Gerardo O.
RF Systems Engineering
National Instruments

I need to read multiple counters using PCI 6601 can I do this, and How?

I am reading 4 TTL signals from a Magnetic Pickup how do I read multiple channels using PCI 6601?

Not concerning my primary question, I would like to point out to an N.I. Rep. that there is a typo in the help section concerning "posting a message".
I have built a large format, two axis digitizer using linear encoders, a 6601 counter/timer, and labview 8. In building my application program, I initially am using two daq assistants, with each set up to accomplish the task of reading two encoders simultaneously. In doing some research, It has come to my attention, that, with my current configuration, errors may result, due to one daq assistant attempting to access the cards driver while the other is acquiring data. All attempts to get two channels working through a single daq assistant have resulted in an error message informing me that I can only have one task per counter.Thus far, I have not seen any noticeable errors, thought I would like to have this device "rock solid", as it will be used extensively.
Is it possible, that I should have purchase an "S" series board instead?

Which infotype are used in ESS/MSS

Dear all,
Please let know which infotype is used in ESS/MSS?
Thanks,
Rashmi

Hi,
ESS & MSS are more about views and not about infotypes. what infotypes they will be accessing depends on the requorement.
They provide portal interface to access HR data stored in SAP.
Refer the thread for more information -
Re: ESS and MSS
Regards,
Amit
Reward all helpful replies.

Is there a VI which reads audio signals off optical SPDIF port?

Hi,
I am trying to capture audio signals from a DAT unit on to the computer's hard drive. Could you please tell me how can I read these signals off an optical SPDIF port using Labview and save the streamed data as a wav file? I am using an audio capturing interface called the Edirol UA-5 to transfer the audio signals from the DAT unit to the Mac's hard drive.
Thanks,
Bhuvana

Hi Bhuvana,
There are not any VIs in LabVIEW designed specifically for SPDIF. There is, however, a tutorial on reading an SPDIF signal using LabVIEW FPGA. You may also be interested in this thread which discusses the use of a digital data acquisition board and the rate needed to read an SPDIF signal.
Jennifer R.
National Instruments
Applications Engineer

Sound pressure signal as input

I want to use a function SV Time-Varying Loudness in the Sound and vibration suite. The output of this function is exactly what I require for my speech analysis.
I have a speech sample recorded from the microphone obviously a voltage signal. This function requires a sound pressure signal.
The voltage signal would be proportional to the sound pressure signal right? How do I convert this voltage signal to the sound pressure signal (Pa).
I'm not even sure if I can use this function. I trying to extract the features from the speech signal. The algorithms used for this are linear predictive coding , perceptual linear predictive coding and mel frequency cepstral coefficients.
I already implemented Linear predictive coding in labVIEW. I wanted to try out Perceptual linear predictive coding because it is considered to be robust in noisy conditions.
This SV time varying loudness function does the exact thing I want to do but I don't know if it is applicable to speech signals.
In the help I says this VI process 2ms blocks of sound pressure data. But speech signals are to be processed only at 10 to 15ms. Please help

Your microphone should have calibration tables to relate the output voltage to an audio quantity like dB or perhaps even Pa.
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

Reading digita signal

I'm looking to write a simple program code that reads digital signal from the PXI-7350 that I'm using. Using LEDs to display the signal whether its high or low.
Just looking for someone to point me the way on how to do this. Thanks

Hi odsnot,
you can search in the Example Finder for "DAQmx". You will find a lot of useful examples.
Mike

Acquiring AC voltage signal using NI 9206 9205 and cRIO

Hello. I am having difficulty accurately acquiring an AC voltage signal using a NI 9206 and cRIO. I'm attempting to acquire voltage signals from two types of Magnelab Current Transformers: split core and rope. In Labview, I first populate an array of size 2,500 with the sensor signal (DIFF mode), then compute the RMS of the array. For the split core CTs, I am able to accurately acquire the correct voltage reading (verified by measuring the corresponding amp on the line using a Fluke 434 Power Analyzer. For the rope CT, however, using the same array/RMS method, I am unable to accurately acquire the correct voltage reading. Measuring the amp on the line using the Fluke 434 PA, the correct voltage from the rope CT should be 0.05v. Using the 9206 (DIFF mode), the RMS from the array gives a voltage reading of 0.071. Now the interesting part is when I measure the line voltage using two different True RMS DMMs, I get two different readings. One multi-meter, a Klein CL2000, reads the correct voltage at 0.05v. Another multi-meter, a Fluke 189, reads incorrectly at 0.071, the same as I get using LabView and the NI 9206. I suppose the question is how is the Klein interpreting the signal differently than the Fluke 189 and the NI 9206 via LabView. One difference between the split-core and rope CTs is that the rope CTs require an external power supply 12-30v AC or DC. I am providing them with 12v DC. I have tried multiple voltages in both AC and DC and still get the same incorrect reading. I'm quite certain it is not a power supply issue, although perhaps the integrator in the rope is creating a unique signal. Any ideas? I appreciate any input.
Thanks,
J.Grant
Solved!
Go to Solution.

AK2DM:
Update - solution found
While the Butterworth low-pass filter sort of worked, it was NOT the solution. I spent some time analyzing the rope CT signals by sampling at a very high rate. The AC signal coming off the rope CTs is triangular NOT sinusoidal. The RMS function in LabView assumes a sinusoidal waveform and essentially calculates the RMS as the average of voltage peaks (for each cycle) / sq.rt (2). Since the AC voltage single emanating from a regular split-core CT is basically sinusoidal, the LabView RMS of the signal gives an accurate reading of the voltage signal. Unable to find a RMS function in LabView for a triangular AC voltage signal, I ended up developing my own custom triangular RMS function in LabView. My function analyzes the signal by finding the peak of every cycle within the signal, takes the average of these peaks, then divides this average peak by sq.rt (3). see this link for formulas:
http://www.optics.arizona.edu/nofziger/OPTI%20380B/Lab%201/AVG%20and%20RMS%20Values%20of%20Periodic%...
Using the triangular method, I am able to accurately acquire the signal off the rope CTs.
Thanks for your help!

How to measure the pulse duration of a TTL signal using AI?

Hi there.
I would like to know how to measure the pulse duration of a TTL signal using an Analog input.
These TTL signals comes from an ultrasonic sensor's output. The pulse width of the signal is
proportional to the distance of the object the sensor detected.
I have tried using the example "Measure Pulse Width.vi" which uses a counter to measure the
pulse duration instead. It provides me with correct results.
However, i will like to know how can i do it using the AI instead.
I tried it by using the example "Acq&Graph Voltage-Int Clk.vi" which i modified by including a
timing and transistion measurement vi. Pulse duration was selected as the output. A graph indicator was also added at the output of the pulse duration to monitor the incoming TTL signals.
However, everytime the TTL signals was detected on the graph indicator, the numeric indicator always produce a "zero" reading.
I have attached my vi for your reference.
Can anybody advice me what i have done wrongly?
Regard.
Attachments:
Acq&Graph Voltage-Int Clkv1.vi ‏190 KB

Hi Paul,
Today i tried using 2 different methods to read the pulse duration of my sensor signal.
Both methods use "Acq&Graph Voltage-IntClk" vi as a guide.
Method1:
Add a filter vi(lowpass/bandpass) and a timing and transition measurements vi.
Pulse duration is selected as the output. With some numeric conversion, a centimeter
reading indicator was created. However, the reading always remains as "zero"
Method2:
Add a Mask and Limit Testing vi and a timing and transition measurements vi.
By adjusting my upper and lower limits, i manage to "filter" a single pulse out from the actual signal.
However, like the earlier case, the cm reading still remains at "zero"
I have attached both the methods resulted waveforms for your reference.
Are there anything that you can advice on?
Regard.
Attachments:
Results_Waveforms.doc ‏141 KB

Read pressure signals using signalExpr​ess

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Read pressure signals using signalExpress