Reduce sample size Signal Express

I need to reduce the sample size from 3 thermistors over a period of about 1 hour.
I'm reading the voltage differential from 3 analoge inputs with a USB-6343 multifunctional DAQ.
I've tried to reduce the sample rate but this gave me an error, so I went back to the default settings of 1kHz for sampling rate.
Is there a way I can reduce the sample size from withing Signal Express (demo version)? I need to be able to output to excel so that I can share results.

Hello REDS,
Thanks for the response. Been out for a couple of days. I'll take a look again Monday.
I'm limited to the LE version of Signal Express 2012, so I believe the "Processing" steps will end up being disabled after the eval period, so I'll be stuck after that. I was looking for a quick off-the-shelf solution when I spent all my money on the DAQ and was hoping that the LE version would have been sufficient to perform simple acquisition and logging functions with the DAQ. Chicken and Egg: couldn't eval SW w/o the HW.
I know some DAQs are limited due to the A/D HW, but the datasheet for the 6210 doesn't specify a minimum sample rate. Would you know of other tricks with the LE version of Signal Express 2012?
Thanks again!

Similar Messages

Using Signal Express VI for DAQmx, timing & file size issues

I am using a Signal Express VI with my DAQmx. Long story short, my DAQmx VI's don't work in LV 8.6 (possibly IT installation error). I have a few issues (I'm a beginner so be easy).
First, I'm confused on how to get the timing correct. I am trying to read a 100 samples (2 channels) average them and repeat this at 30Hz and record this data.
Second, everytime I open the Signal Express VI (in my block diagram) and change sampling for example, click OK, then save my VI before running my program. I noticed the file on disk increased in size by the megabytes! All I changed were the sampling settings.
I appreciate any input, thanks in advance!
-Michal
Attachments:
Philtec_09-22-09.vi ‏2589 KB

To your first concern, it sounds like DAQmx was installed before LabVIEW. Just reinstall DAQmx and it will work fine in LabVIEW.
For you second concern. To get 100 Samples at 30 Hz, you will need to change your channel setup in signal express. You will need Continuous Aquisition, with 100 Samples to Read at 3000 Hz. Then you code should work as expected.
Chris Bakker
National Instruments
Applications Engineer
Check out LabVIEW 2009 and the New X-series DAQ!

Set up Signal Express to log when there is a change in state of the inputs (NI USB-6501 logger)

Hello NI Forum, I have recently purchased digital I/O logger NI USB-6501. This arrived with Signal Express, which I intend to use as a Lite version. I just wondered if it was possible to set up Signal Express to only add a log entry when there is a change in state of the inputs? I have this working on a 0.1sec sample period and can interrogate the logs after recording. Most of the time nothing will be happenning, I just wondered if there was a way to reduce the ammount of data captured? Cheers.

Ah that unfortunate, and yes start/stop conditions for loging are part of the Full version of SignalExpress
Here's the comparision: http://www.ni.com/labview/signalexpress/purchasing-options.htm
Sorry about that

Signal Express Play Back Help

I have logged a signal in Signal Express. The logged signal was a force aquired from a NI DAQ system. The logged data consists of a number of peaks all of difference magnitude and period. My goal is to get a list of each of the peaks maximum amplitude so I can later average these force components for analyzation.
I can already find the MAX amplitude using the amplitude and level function. This does not help me though because it only records the maximum value over the entire experiment.
Can I do this application in Signal Express? I do NOT have the ability to purchase addtional software such as diadem to do this. I am hoping to carry this out all in the LabView signal express project.

Hello erb174,
In LabVIEW SignalExpress, there is no direct way to get all of the peaks in your signal. However, during playback, you have the option to break your playback file into smaller chunks instead of playing back the entire file all at once. To do this, from the playback part of the project, select the tab Playback Options. In there, there is a block size input in the Playback block configuration section. Using this, you can select the number of samples of your recorded signal to playback at a time. You can pick a number of samples that is sure to contain only a single peak. I then used the Amplitude and Levels step to search for the peak in the current subset of my recorded data. From there you can save this data to an LVM file. This will get you a list of peaks you created.
You could also consider creating a custom LabVIEW step that would search for the peaks for you. After you create this step you can distribute it with your SignalExpress project.
Regards,
Browning G
FlexRIO R&D

Labview signal express to excel

Hello,
I'm using Labview signalexpress to acquire a signal. My problem is that I acquire 20 seconds of my signal (and I see it on the graph), but the problem is that I can export to excel the only 1.35 seconds, whatever the number of samples. How could I export to excel the entire signal?
Thanks
Solved!
Go to Solution.

I don't have signal express but a quick search found this link. It states that there is a setable limit on the size fo data sent to the clipboard.
"When you export data to Microsoft Excel, LabVIEW SignalExpress copies data samples to a clipboard for export. Use theMaximum Clipboard Data Export Size option on the Data page of the Options dialog box to increase the number of data samples the clipboard can contain. Depending on the amount of memory on a machine, large log files might not export successfully."
You might be running into that limitation when you try this method. Even if you increase the limit you will still not be able to paste more than excel's max size as discussed already. You would have to paste it into a text file or some other program that can handdle that much data. I would not use this method however. Seems like it would be to easy to make mistakes that way.
A .lvm file is just a text file so you should not run into any limits there. This is what I would use.
Lukin
Certified LabVIEW Developer

Can Signal Express prompt the user for the next ascii file name?

I am using the following to collect data from Thermocouples and Strain Guages in our plant. It allows me to plt data every second, while recording only every 3 seconds to cut down the file size.
Big Loop-
Small Loop-
      Conitional repeat...
      DAQmx Aquire...
      Statistics (mean) Temp...
      Statistics (mean) Press...
      Current Iteration...
End Small Loop-
Save to ASCII/LVM
The problem is that I have to configure the save step as "overwrite once, then append" so I get a single file each time the project runs. How can I get Signal Express to either prompt the user for a new file name with each run or have the ascii file saved into the log directory for that run. As it stands now, the file gets overwritten with each new project run.
Thank you.
new user

Hi crawlejg,
You can set signal express to increment the file being created each time. But if you are looking for 1 new file each time the project runs you will have to use LabVIEW as this advanced functionality is not available in Signal Express. If you need help getting this to work in LabVIEW or have any other questions please feel free to ask!
Sincerely,
Jason Daming
Applications Engineer
National Instruments
http://www.ni.com/support

How to program encoder pulses in Signal Express to read out in degrees

I have people requesting a Signal Express application that can display rotary machine degrees (0.0-359.9), with input from an encoder to a 6602 counter card. Can this be done in Signal Express at all and if so, what is the easiest way to program it?

Hello David,
in the same way, i configured a linear position encoder.
In the continious sampling mode, I can't save the displacement channel.
Is there any other option to save the Channel witrh e.g. 20 kHz?
Regards,
Andreas
Attachments:
Schritteinstellungen.jpg ‏124 KB
Aufnahmeoptionen.jpg ‏59 KB

How to reduce the size of System tables(RS*) in SAP BW?

Hi All,
We need to reduce the size of a system tables(RS*) in SAP BW system without impacting anything to system.
Could you please let us know is there any Global program/Function module to do the same.
If not if you know any individual program or other way to reduce the system table size it will be very much useful.
Sample System tables(RS*) are given below.
RSHIENODETMP
RSBERRORLOG
RSHIENODETMP~0
RSBMNODES
RSBKDATA
RSBMNODES~001
RSRWBSTORE
RSBMLOGPAR
RSBERRORLOG~0

Sudhakar,
There are tables you can archive / clean up and then there are tables you cannot do anything about. For example - if your system has a million queries - the RSRREPDIR , RZCOMPDIR tables will be large.
The tables that typically get archived are :
1. BALDAT / BALHDR - application log tables
2. Monitor tables - search for Request archiving which will tell you how to archive the same
The other tables -
First you would have to understand why they are large in the first place ... if you have too many hierarchies - then some tables can be huge - delete some of the hierarchies you do not need and the table sizes should come down.
RSRWBSTORE - this is the internal store for workbooks - this will have the last executed version of the workbook stored in the table. This information is called when the workbook is executed without refreshing the variables - which is why you get the workbook output first and then get prompted to refresh the variables.

Undo reduce file size

Worked up documents on Pages with multiple photos, some at high resolutions. Reduced file size for emailing and sending to dropbox and now want to print in an 18" x 24" size. Sample print is very blurrry How do I undo reduce file size? Would exporting file via pdf (best file quality) help? Any other suggestions. Much aprreciated.

Hi Trudy,
Reducing file size works by reducing the file size of any high resolution images to 72 dpi, OK for on screen use, but quite pixelated if printed or enlarged. Here's an example:
Here's the original—This is a detail, enlarged to 400% on the screen, but reduced by the discussions software to fit on this page. Note the spider web below the frog.
Here's the warning you get when you choose Reduce File Size:
Note that it says it "replaces" the original versions of the images. Scarey thought, but not as permanent as it appears.
Here's the result:
The frog's snout is quite pixillated, and the web has almost disappeared, as has much of the texture of the frog's skin and of the rough-sawn cedar siding behind. Again, a 400% enlargement on the screen, with the reduction imposed by the discussions software.
If you act at this point, it is possible to undo the change—throwing out the edited image and replacing it with the original version. The option appears to remain available even after the document is Saved, but disappears when it has been Closed. That would make sense, as Saving both the reduced image and the full version would not result in a reduction in file size.
But there's one other factor: When you drop an image onto a placeholder in Pages, the image that is inserted is a COPY of the original image file. The editing referred to above is done with that copy, not with the original image file, which continues to exist, unchanged where it was before being inserted.
To get the hi-res version back, then is a matter of dropping the original file onto the placeholder again.
Seems to work.
Regards,
Barry

How to view signal in a waveform chart in Labview Signal Express?

Hi,
I would like to view a signal in Signal Express 3.0 in a "waveform chart" but don't know how to do it and I am thinking that it may be impossible?
In Labview there are two ways of viewing data, either in a "waveform chart" or in a "waveform graph". The great thing with "waveform chart" is that it lets you define a history length and you can see the data move to the left (strip chart option) as the samples are being retrieved. It works perfect.
In Signal Express I can only select "XY graph" or "Waveform graph" by making a right-click the mouse but I cannot select "Waveform chart". Is it really true that it is not possible to view the data in a "waveform graph with Labview SE? (1 analog signal being read continuously, 100 samples to read at 1K rate)
Thank you in advance,
Enrique
Solved!
Go to Solution.

Hi Enrique,
You are correct that there is currently no waveform chart in SignalExpress. The closest thing you can get to, is recording the data as a log and then viewing it while recording (which I realize is not quite the same, interactive behavior).
For your last comment, you wrote "waveform graph", but I assume you meant to say "chart" there as well.
Sorry about this. We have recently been getting this request, so perhaps in a future version.
Phil

Why can I only import one TDMS signal at a time in Signal Express?

I have dozens of data files which were originally recorded as LabVIEW waveform files. I converted them all to TDMS in LabVIEW in hopes that I could import them to Signal Express (with the S&V Suite) for further processing. Each data file contains more than 20 channels.
When I try to import them to SE, I am unable to import the entire group. Instead, I am limited to one channel at a time. This would take days to import all channels, and is not what I want at all. Is there some way to import an entire group of channels at once?
JR

I was using the "Logged Signals from LabVIEW TDMS file" import; perhaps I had installed it on SE 2.5 before upgrading to 3.0. Regardless, I downloaded the ZIP file, and ran the msi with the "Repair" function. This did not change the functionality. I then used your suggestion, and redigitized one of the files with the Express VI set for TDMS. Same deal, although instead of the channel names I had been able to specify using the TDMS subVIs, now it lists them all as "Voltage_x", where x is a channel number beginning with 0.
I've attached two images as examples of what I'm experiencing. The first (temp1.JPG) shows where I've tried to select the entire group. You can see that "Convert File" is not enabled, and the sample information has not been read. The second image (temp2.JPG) shows where I've selected a channel. I am only able to select one channel, not a range. The "Convert File" button is now enabled, and sample information is correctly displayed.
Attachments:
temp1.JPG ‏57 KB
temp2.JPG ‏57 KB

Using signal express with NI9227 timing settings

I have Signal Express LE and using modual NI 9227, I am trying to measure input current draw AAC. What should my timing setting be for "Acquisition Mode," "Samples to Read", and "Rate (Hz)" be if I want to read every .5 seconds and every 1 seconds? Can someone explain to me what the Time Settings mentioned above mean. I am a Lab Technician learning as I go. My EE's are very busy and want me to do as much as I can on my own, please help.
Thanks
DustDevil

DustDevil,
First, welcome to our forums!
Second, we have a great KnowledgeBase article here that talks about the various timing settings you have available and what they each will mean for the timing of your measurements. In that article, "number of samples per channel" corresponds to the "samples to read" you have available in SignalExpress.
Also, the 9227 is one of our modules that uses Delta-Sigma modulation to get a higher resolution, which has some caveats as far as sampling rate is concerned. There is a minimum data rate (about 1600 samples per second) that you cannot sample below. If you set a rate lower than 1600 you'll still be getting data back at 1600 S/s. This help file describes the "Subset and Resample" step you can use in SignalExpress so you can acquire data at the minimum rate of the device and then resample the result to end up with data at the "rate" you actually want.
Give those a look and re-post if you have any follow-up questions or need clarification.
Best,
National Instruments

Labview Signal Express and Matlab

Hello,
I am using Labview Signal Express to acquire and log data from an injection moulding machine (with NI USB-6218).
The logs contain more than 65000 samples so my boss told me to treat the data with Matlab.
Can anyone tell me how to do that? (I think that I have to export these data in a text file before but how???)
Thank you very much for your help
Regards.
Helene

Hi there, I’m currently studying mechatronics in Sligo institute of Technology in Ireland and we have to do a SCADA project using LabVIEW to control an injection moulding process. I work in the Water and waste water treatment area so I’ve no experience of Injection Moulding. I found your address on the web and was wondering would you have any screen shots of what an injection moulding SCADA interface would look like or a schematic/P&ID of an injection moulding process. Any help would be greatly appreciated. Regards Richard Crowe

Signal Express Large TDMS File Recording Error

Hello,
I have the following application and I am looking for some tips on the best way to approach the problem with Signal Express:
I am attempting to using Signal Express 2009 (Sound and Vibration Assistant) to collect random vibration data on three channels over an extended period of time -- about 20 hours total. My sample rate is 2kHz. Sampling at that rate over that period of time invovles the creation of a very large TDMS file, which is intended for various types of analysis in signal express later or some other application later on. One of the analysis functions to be done is a PSD (Power Spectral Density) plot to determine the vibration levels distributed over a band of frequencies during the log.
My original solution was to collect a single large TDMS file. I did this with Signal Express recording options configured to save and restart "in current log" after 1 hour worth of data is collected. I configured it this way because if there is a crash/sudden loss of power during data collection, I wanted to ensure that only up to an hours worth of data would be lost. I tested this option and the integrity of the file after a crash by killing the SignalExpress process in the middle of recording the large TDMS file (after a few save log file conditions had been met). Unfortunately, when I restart signal express and try to load the log file data in playback mode an error indicating "TDMS Data Corrupt" (or similiar) is displayed. My TDMS file is large, so it obviously contains some data; however, Signal Express does not index its time and I can not view the data within the file. The .tdms_index file is also present but the meta data.txt file is not generated. Is there any way to insure that I will have at least partially valid data that can be processed from a single TDMS file in the event of a crash during mid-logging? I don't have too much experience dealing with random vibration data, so are there any tips for generating vibration level PSD curves for large files over such a long time length?
My solution to this problem thusfar has been to log the data to seperate .TDMS files, about an hour in length each. This should result in about 20 files in my final application. Since I want to take a PSD, which ends up being a statistical average over the whole time period. I plan on generating a curve for each of these files and averaging all 20 of them together to get the overall vibration PSD curve for the 20 hour time period.

JMat,
Based on the description of your application, I would recommend writing the data to a "new log" every hour (or more often). Based on some of my testing, if you use "current log" and S&V Assistant crashes, the entire TDMS file will be corrupted. This seems consistent with what you're seeing.
It would be good if you could clarify why you're hoping to use "current log" instead of "new log". I'll assume an answer so I can provide a few more details in this response. I assume it's because you want to be able to perform the PSD over the entire logged file (all 20 hours). And the easiest way to do that is if all 20 hours are recorded in a continuous file. If this is the case, then we can still help you accomplish the desired outcome, but also ensure that you don't lose data if the system crashes at some point during the monitoring.
If you use "new log" for your logging configuration, you'll end up having 20 TDMS files when the run is complete. If the system crashes, any files that are already done writing will not be corrupted (I tested this). All you need to do is concatenate the files to make a single one. If this would work for you, we can talk about various solutions we can provide to accomplish this task. Let me know.
Now there is one thing I want to bring to your attention about logging multiple files from SignalExpress, whether you use "current log' or "new log". The Windows OS is not deterministic. Meaning that it cannot guarantee how long it takes for an operation to complete. For your particular application, this basically means that between log files there will be some short gap in time that the data is not being saved to disk. Based on my testing, it looks like this time could be between 1-3 seconds. This time depends heavily on how many other applications Windows has running at the same time.
So when you concatenate the signals, you can choose to concatenate them "absolutely", meaning there will be a 1-3 second gap between the different waveforms recorded. Or you can concatenate them to assume there is no time gap between logs, resulting in a pseudo-continuous waveform (it looks continuous to you and the analysis routine).
If neither of these options are suitable, let me know.
Thanks, Jared

Memory full error in Signal express

Hi All,
I am trying to log the data using Signal express for 14 channels sampling at 50kS/s. I have a test where we need to perform a continous logging for 100 hours at 50kS/s and samples to read as 5000 .I did a test logging for 24 hours, but Signal express stopped running after 15-16 hours. Do you have any suggestions ? I am attaching the screen shot.
I am writing the .tdms files to an external HDD (3 TB) and using a Windows 7 PC.
Please let me know if you have any suggestions
Attachments:
Memory full.zip ‏1050 KB

That is a considerable amount of data to be continuously logging.
How much system memory does your computer have?
Some suggestions you could try would be to (if you have admin rights) disable any unncessary processes that launch at startup. Increase your page file allocation or at least open the task manager and take a look at the PF activity.
What interface type does your external HDD have? If its anything other than SATA I, II, or III that may be contributing to your bottleneck.
My guess is that its a system limitation and not a Signal Express issue. But I may be wrong.
I've logged data for days on end without issue before; although not at the sample rate you are.
SCXI- 1000 Chassis w/ 1346 adapter
PCI 6281 DAQ card
SCXI- 1520 Bridge Board w/ 1314 Terminal Block (x2)
SCXI- 1180 Feedthrough Panel w/ 1302 Block
Signal Express 2014.
Win7 Enterprise

Reduce sample size Signal Express

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