Single Express Export to Ascii - Not logging time

[MgDAQ]

I am logging two voltages to signal express.  When I export the data to ASCII, the time is not transfered. The start time and stop time are listed in the file, however the actual time for each sample is not recorded. How do I correct this?

[thehobbs]

What version of SignalExpress are you using?  Are you using the Save to ASCII/LVM step?  If so, you want to make sure the X Value Columns parameter is not set to Empty Time Column.  If not, please provide more information about what you are doing, as the right-click >> Export To option also exports time data for me.  I am using SignalExpress 3.0.

[MgDAQ]

I am using an evaluation version of Signal Express 3.0. My company is testing this software to see if it will meet our needs. I am not automatically savinging to an ascii file.  I go to the logged data under logs, right click the voltage I recorded and select covert to ascii. 

[Jordan F]

You could also right click voltage under logged data and "Export to Microsoft Excel".  This should export the time data with your voltages.  Also, as Jason said earlier, you could add a step after your DAQmx Acquire step that saves to and ASCII/LVM file.  This is done by going to Add Step>>Load/Save Signals>>Analog Signals>>Save to ASCII/LVM.  Also, I would recommend reading the labVIEW Signal Express Help on how to save to an ASCII/LVM file (Contents Tab>>Step Reference>>LabVIEW Signal Express Steps>>Load/Save Signals>>Save to ASCII/LVM).

[MgDAQ]

I am unable to export to Excel because the file is too large. I will make the change to save the data to an ASCII/LVM file for future logs, however I have 4 logs of data I would reallly like to have time data with. One would assume if the option was there to convert to ASCII after logging it is uncessary to add the step of saving the signal.

[thehobbs]

The ASCII file should have a dt value exported to it.  You can use this dt value to determine the time data for each sample.

[MgDAQ]

I have spent weeks trying to work with the data. The data file is too large for excel to import, so using excel to calculate dt is not an option. I refuse to do it manually. I consider all the data optained now lost. 

[Jordan F]

Hi,

Can you open the ASCII (text) file?  As Jason said above, there should be a dt value associated with the data.  This value shows the time between samples.  Also, look for a start and stop time (absolute time).  From this you can tell when the data was sampled.

[MgDAQ]

Yes of course the Ascii file can be opened. I have never had a problem opening it.  The problem was that there was no time stamp placed next to each data point. The file simple provided a start time, stop time and dt. Originally the Ascii file was created after the data logging. The file was too large to import to Excel to use the spreadsheet to fill in the dt for each data point.

I made the changes above to automatically save to Ascii and reran a mock run of the data I want to log. This did not solve the problem. As before the start time, stop time, and dt were provided, but no timestamp for each data point.  I was able to tell Single Express to only log so many data points, unfortunately this function was ignored as when I went to import in excel, the file was again too large. This time however Excel offered to open a portion of the data with an error to add the rest later. 

I do not want to truncate the data to use in Excel and I do not want to use Single Express' playback function for my analysis. I simply want to pull the data out of Single Express, and use it in an analysis program of my selection such as Excel.  Needing a timestamp next to a logged data point without having to manually go in and place it there is not a strange request.  I am beginning to suspect Single Express simple does not provide this typical feature found in other data logging products.

[Jordan F]

As was said earlier in the posting, you can have associated time values with each data point in a generic ASCII file by setting the X Values Column and the Time Axis Preference in the Save to ASCII/LVM step.  I attached a screen shot of what to have everything set at to show how to do this.  Also, I have attached my signal express project to show how to do this.  However, if you have logs that were not saved this way, then you will not be able to view them with the time column shown (you do have the dt and start and stop time). 

Message Edited by Jordan F on 01-27-2009 03:57 PM