File formats

[ignisuti]

I was initially logging my data as CSV format since I thought that would be most versatile format for me to analyze later. I then changed to DDF format due to errors I was seeing. The theory was that the conversion from native DasyLab format to CSV was taking too long or causing data alignment issues. That didn't help much with the errors. The errors still occur consistently whenever I switch the computer's focus away from Dasylab and start copying files to my thumbdrive. 

So, now I have a lot of DDF data that needs to be converted to CSV data. I've created a read module for the DDF file and pumped that data into the write module configured to output CSV files. That does work, but takes almost as long to convert the data as it did to record it in the first place. Is that normal? I've got over 50 files containing roughly 20 hours of testing to convert... 😞

Also, is CSV the best approach here for analyzing my data? What other tools/methods can I use with the DDF format? For instance, I have a ton of Analog data. It would be really nice to graphically see those waveforms using the Y/t chart and be able to scroll-to (or zoom-in) to a particular spot in time. Is that possible? 

[CJ_Butler__DASYLab_Pro]

Change the Read Data module to disable the Output in real time switch.

If copying files to the thumb drive is causing errors, you're running on the edge... you shouldn't use the computer to do anything else while the data is being acquired. 

[CJ_Butler__DASYLab_Pro]

DIADEM!!!!

Either save the data in the DIADEM TDM formation, or get the DASYLab DDF plug in for DIADEM.

http://www.ni.com/diadem/

[ignisuti]

Unchecking the real time box did help quite a bit. I still have to input the files 1 at a time. When I logged the files, I used the multi-file feature. So, all my files say "G3_Data_####.DDF". I'm now trying to use the multifile feature on the Read module, but I get an Read Module failure after the first file conversion to CSV completes. It says "This multifile was written with a different starting time", It's referring to the 2nd (not 1st) multifile when it says this.

I do love that I can replay the DDF data into Y/t chart. However, I need a way to select the time. i.e. scroll forwards and backwards in time so I could quickly look at 6 hours 31 minutes into a test. Is there a way to do that? If so, I think I can skip the whole convert to CSV step.

The Diadem looks interesting, but I don't think I'm going to get my management to buy yet another tool. 

[Kaleb_A]

ignisuti,

Could you use MATLAB to read the ddf data and convert to ASCII? Then excel can (hopefully) quickly import the data. Then you could save it as a .csv file. 

http://forums.ni.com/t5/DASYLab/how-to-import-dasylab-data-ddf-to-LABView-or-MATLAB/td-p/1188297

Best regards,

[ignisuti]

That sounds like it'd work, but what I really want right now is the ability to scroll to a specific spot in my data (from within DasyLab). Is there anyway to do that?

[ignisuti]

Can someone please give me a YES or a NO regaurding whether DasyLab is able to do what I'm asking?

To summarize... I simply want to use a Read Module connected to Y/t chart to display my waveforms. But, I want to move back and forth to specific spots in time. 

[CJ_Butler__DASYLab_Pro]

If you increase the time axis (x-axis) of the Y/t Chart, and then zoom in, you can use the arrow controls to zoom back and forth.

The Chart Recorder has a better scroll function, but it's possible that memory limitations for both the Y/t Chart and the Chart Recorder may limit how much data you can display at one time.

For higher speed data, the Chart Recorder takes a long time to draw all of the values. If you increase the Y/t Chart time, it will take a long time to plot the data as well.

You can read the data back, and do a data reduction on it, using the Separate module. That would write the data faster, but might lose the events that you're looking for. 

There is a difference in approach for reviewing data "on the fly" as DASYLab does, compared to how a post analysis package does it.