continuous recording of samples in file .lvm with data acquisition
I use DAQ to acquire the analog signal and I'm saving samples k 1 .lvm file using file capable of writing with a sampling frequency = 1 k, samples = 1 k in continuous mode. I am able to see the data stored in the .lvm file like this 1 k samples then a few lines of words (like channels, samples, date etc.) and then other samples of k 1 and so on not worked the .vi stopped but how to save the continually samples placed in without any line of words I mean save continuous samples.
The sequence is shown it the file attached is .lvm.
It would have been preferable to set the code when you set up the Express VI. You just leave the Express VI in its default settings? Have you tried to change the configuration to one header only?
Your choice of an Express VI means you have limited options. If the options do not match your needs, you will need to use lower entry level file functions.
Tags: NI Software
Hello I just receive the NI 9265 Daq for research in my lab. I'm trying to present entry and display it on an oscilloscope. I don't get anything. I did some research on the internet, so my question is do you need a power supply to the current entry with data acquisition or 9265?
Read the data sheet. Clearly on the first page is a sentence which reads "the NI 9265 requires 9 V to 36 V external power.
Hi, I use this command to export my schema
exp file = c:\expdat.dmp med/med
I think that if I use the same command over and over again, it will replace the old file with the new one? right?
2. I want to name the file exported with the sysdate (date and time)? , and I think it's a way to create a new file and does not replace the old file.
Here is an example of adding a date for a file name:
> exp med/med file=c:\expdat.%date:~10,4%%date:~7,2%%date:~4,2%.dmp
To add as a data and once, you just need something based on time that is unique, so try something like:
> exp med/med file=c:\expdat.%date:~10,4%%date:~7,2%%date:~4,2%.%time:~1,1%%time:~3,2%%time:~6,2%%time:~9,2%.dmp
I have a rectangular steel beam that is affected with a weight of 100 kg and I would look for the modules able to sample the signal correctly.
The Nyquist theorem says that if half of the sampling frequency is higher than the input signal, it will be recorded correctly.
What I think about it before you buy a data acquisition module to find the signal of the rectangular steel beam? I will perform an analysis model by finite elements using the elastic properties or properties of plastic? Is the natural frequency of the associated structure of the input signal?
Some technical assistance is appropriate, determine that the higher frequency component is interesting to your signal. Set your frequency of sampling to twice this value. In addition, to protect data, to build a filter of antisliasing of material it alleviates any energy above the highest frequency of interest.
I would like to have a very low cost measurement system loop which I can plug in my laptop current:
I have a load, which is connected to a circuit of air conditioning/signal booster, which output a 4-20mA. I want to measure this current loop signal.
An idea for the lowest cost system? I think that the most NOR DAQ are too expensive and too exaggerated.
I have LabVIEW.
Use of remote sensing current low-value resistance, then measure the fall of voltage through it with the help of an acquisition of data 6008/6009? They have about $150.
You will probably need to amplify current-sense with a MAX4372 or similar resistance to achieve a result that allows you to use a reasonable scale on data acquisition. I measure the current through our products in almost all of our equipment to test in this way. The size of the resistance of meaning as a result. The 6008 is accurate enough, but it is not the fastest nor well presented. But starting at $ 150, they are hard to beat.
Please see the attached VI. (LV2012)
What I want to do is to generate a file name in the format: DayOfYear - month - day - year. txt
The way I coded it, I was able to generate according to my condition. For example today it generated a file name ' 14-1-14 - 2016.txt ' on my computer.
But the same code when it is run on the client computer generated this: 14-1 /-4 /-016 .txt and, of course, the VI ceased due to the illegal file name. I gues this is because how each computer formats the date, the time information.
How to code a generic VI to create the name of the file that I need on any computer?
Just let the Date/Time Format string to do all the work...
can I connect this PE sensor to a NOR-9232?
There is not much info here... What worries me is the use of pC/g instead of mV/g.
A piezoelectric sensor with output load requires a signal conditioning circuit to convert a voltage of this accusation. While, in principle, a capacitor will do the job, in practice very careful circuit design may have to get accurate results.
The 9232 NOR is designed to work with IEPE sensors, which have built-in signal conditioning. If dig you deep enough into the specifications, you will find that the input impedance is 324000 ohms, which is much too low to work directly with a piezo sensor.
You need a signal conditioner. The data sheet that you have linked lists conditiners signal among the accessories.
I'm sampling of 8 channels at 2.5 MHz I I need to know if the DAQmx 6133 I use gets every channel at 2.5 MHz or if she gets every channel (2.5/8) MHz. For example if I had a channel it can get up to 2.5 MHz, but if I get 8 channels, this channel will get samples in high 312, 5 kHz (= 2.5 / 8 MHz).
Can someone help me out here?
The NI 6133 is a module for simultaneous sampling. This means that there is an NOC for each channel on the device. If you look at the Specifications for the 6133 OR you can see that the maximum sampling frequency is specified as 2.5 MS/second. There is one by the channel for this device specification. Thus, you can enjoy all 8 channels at 2.5 MS per second instead of having to use the overall rate of 2.5/8 MS/second when acquiring on all channels.
I try to get my remote system (SMU remote system) to send a signal of analog voltage by reading a file .lvm.
I have a project in real time implemented, and under my remote system, I have a VI that is supposed to give a signal of analog voltage.
The implementation of VI begins by reading a file position (.lvm). After that, it is connected to a DAQ assistant.
I'm already sure that everything is connected properly, and that it is the right channel. The reason why I'm sure is because in the DAQ assistant window, I can click on "run" in order to send a test signal. I am able to capture this signal to test with an oscilloscope. Therefore, I am sure that the system is all set up correctly.
Finally, I don't know if it's important, but the measure file he was reading is located in my host. I don't know if I deploy when the VI to the target, if the measurement file is sent to the remote system with the VI.
I was wondering if someone could help me please.
If I understand correctly, you are trying to read a file .lvm waveform data and send this waveform through your SMU system. What devices are specifically using (chassis, modules...)? What exactly happens when you run the VI? You see errors? If so, what are the codes that come with these errors? Additional information on what the file .lvm would be also useful. What are the functions you use to play the .lvm file?
I created this file LVM after the acquisition of my signal. Right now I have a problem of extracting data from this file LVM. For example the data in the cell B24 to J24.
I didn't have something like that because it should be relatively simple. I used loops and methods to extract the data, but she return me the value NaN or another number. I don't know what is happening.
The attachment is LVM I created. Please help me with this, thank you
Use the Express VI to convert the type of dynamic data in a 2D array. Then the index on the column in your table.
You can also check the integrity of your data. In your file, the first line of data is fairly complete. Later lines have several empty columns before and after the 4 columns of data.
When I ran the attached VI extract, I noticed she has imported the data, but the columns other lines not aligned with the first complete line in the same way they do when I saw your file in Notepad. You will get many NaN for wherever your data are empty.
Im having issues return timestamps from a LVM file and an excel file.
Ulitmately, I have a series of files LVM with 6 channels of data and timestamps of correspodning.
When I read the back files in a table, the channel values are analyzed, but the timestamp is no where. The channel data then exported successfully to an excel sheet (less the time stamps).
How can I extract the timestamps with the channel data and bring them into an excel sheet?
NOTE: I do not know you can open the file LVM directly in excel, however, information is not "analysable.
I appreciate the toughts. I have attached my experimental code as well as the data set, I am trying to extract. I have also included a spreadsheet excel destination.
Is there a reason that you do not simply write it as File.vi to write your signal data in the excel worksheet? It is an easy way to put in your signal data to an excel spreadsheet (see file attachment). You can also view the code in this Express VI to see how this is achieved.
I have headaches display my data with correct timestamp. There are so many methods to save the data. Here, I decided to save it in a text delimited as lvm. a screenshot of my vi segment is attached. I want to use this way rather than other methods is the flexibility it offers. I'll be able to add more data to store that I develop the vi. (So I'm storing data of the DAQ assistant and my calculated values.) I've attached a screenshot of the file I also read.
I would use another vi to open this file and it draw a chart/graph to show a trend of the acquired data. Can someone pls Advisor mid on which is a better way for mi to do?
Thank you very much!
Sorry for the late reply, I was rushing to complete my project, has not been able to answer.
Yes, I managed to solve it. In any case, I've used this high rate in the acquisition of data wizard is to allow the acquisition of continuous mode & use a software filter instead of filter material. However writes to the folder this way - write string in .lvm, max is 10 samples/s unless I have use tdm (I'll then everything in the newspaper).
I was not able to display the correct timestamp was due to the fact that I have does not add to the timestamp of the start time for the timestamp in waveform display. I won't be able to go down to my lab, & my machine have no LabVIEW, so what I do is to extract some parts of my report to share.
For the part that I used to display the graph (can be seen on the attachment), I deleted the 1st column, which is the time stamp (for display of the spreadsheet), but extract the 1st element - convert timestamp DBL it when I start recording in the DAQ vi (written with the header).
This excerpt (which could be considered as a group of numbers in the file lvm) and converted to the type timestamp and wired for generating waveform block, providing the start time of the wave.
Then I replace the use of the chart with graphic, graphic is suitable for data acquired and graphic tracing is better for the time of execution of the data display. now it seems to work fine for me, except for the load time may take some time for larger files.
Thank you for your participation in this thread!
See you soon!
I encountered a problem and you need help.
I collect tensions and corresponding currents via a card PCI-6221. While acquiriing data, I would like to see the values on a XY graph, so that I can also check current vs only voltage/current / time. In addition, data should be recorded on the acquisition.
First, I create hannels to analog input with the Virutal DAQmx channel create, then I set the sampling frequency and the mode and begin the tasks. The DAQmx.Read is placed in a while loop. Because of the high noise to signal, I want to average for example every 200 points of the current and acquired for this draw versus the average acquisition time or average voltage. The recording of the data should also appear in the while loop.
The first thing, I thought, was to run in continuous Mode data acquisition and utilization for example 10 k s/s sampling frequency. The DAQmx.Read is set to 1 D Wfm N Chan N Samp (there are 4 channels in total) and the number of samples per channel for example is 1000 to avoid the errors/subscribe for more of the buffer. Each of these packages of 1000 samples should be separatet (I use Index Array at the moment). After gaining separate waveforms out of table 1 d of waveforms, I extracted the value of Y to get items of waveform. The error that results must then be treated to get average values.
But how to get these averages without delaying my code?
My idea/concern is this: I've read 1000 samples after about 0.1 s. These then are divded into single waveforms, time information are subtracted, a sort of loop to sprawl is used (I don't know how this exactly), the data are transferred to a XY Chart and saved to a .dat file. After all that's happened (I hope I understood correctly the flow of data within a while loop), the code in the while loop again then 1000 samples read and are processed.
But if the treatment was too long the DAQmx.Read runs too late and cycle to cycle, reading buffer behind the generation of data on the card PCI-6221.
This concern is reasonable? And how can I get around this? Does anyone know a way to average and save the data?
I mean, the first thing that I would consider increasing the number of samples per channel, but this also increases the duration of the data processing.
The other question is on the calendar. If I understand correctly, the timestamp is generated once when the task starts (with the DAQmxStartTask) and the time difference betweeen the datapoints is then computed by 1 divded by the sampling frequency. However, if the treatment takes considerable time, how can I make sure, that this error does not accumulate?
I'm sorry for the long plain text!
You can find my attached example-vi(only to show roughly what I was thinking, I know there are two averaging-functions and the rate are not correctly set now).
Best wishes and thank you in advance,
PS: I should add: imagine the acquisition of data running on a really old and slow PC, for example a Pentium III.
PPS: I do not know why, but I can't reach my vi...
As stated, whenever I have download an image with the command "save image under" he recorded in a useless file of 168 bits. This does not happen everytime I have save an image, but more often the not, and I don't have a lot of useless files hang out because of this. Is it possible to re - download each image 168 bits that he should have been downloaded in the first place? Is it possible to ensure that this does not happen?
Here's what it looks like:
This means that you are not allowed to do this action.
The site could use a transparent overlay image to protect the actual image or otherwise has put in place a protection.
You can check if see you the image in "tools > Page Info > Media ' and save it.
I would like to be able to read at least 4 million lines of data total 32 million lines at a time. The TDMS file has given for 2 channels and no time data. If I can convert TDMS files in one or more files LVM, I can read large files of LVM using the JMP software. I'm using Labview 2009. Please provide suggestions.
Thanks in advance. Best regards, Manish (Univ of a to z)
For your problem with is .tdms to .lvm, take a look at this forum and This example of community. I checked out, and in my opinion, he should be able to work well for you in regards to creating multiple files .lvm from single .tdms file. The only thing that could be a problem is the time requirement to enter all in LV, and saves data to several files, but you will encounter when you work with large consumed data.
I would also suggest that you take a look at tiara if you are searching by analyzing large data sets. The program is designed to manage large sets of data and make the analyzation on the data.
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