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LJlogger file question


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#1 Guest_Ken Jennejohn_*

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Posted 12 June 2003 - 08:03 PM

When I look at the Excel file created from the original .dat file generated by LJlogger, I notice the first column under 'seconds' always reads 3.14+09. Isn't this the elapsed time in seconds from the start of the scan? Is there any way to get this to work properly? Thanks for the attention. Ken Jennejohn

#2 LabJack Support

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Posted 12 June 2003 - 08:58 PM

I have cut/pasted information from the old forum:

http://www.labjack.c...;num=1041978325


LJlogger does not have an option to change the time format it uses, but you can manipulate the time in Excel as you suggest.

The time is seconds since midnight January 1st (Universal Time), 1904.  Many languages have routines to convert this to other formats.

If you are just seeing 3.11E9, you need to expand the column width so you can see all the digits.  You also might want to show a couple decimal places.

Many people make a new column where they subtract the initial time ($A$4) from each time, and thus are left with relative time.

By default, Excel stores dates as days since 1900.  So to convert the LJlogger times to the default Excel date format, you can divide by 86400 and add 1462.  Note that the LJlogger time is Universal Time, so for instance, to convert to local time in Colorado, USA, we need to subtract 7 hours.


We chose to write the time in seconds, because in our opinion it is the most general format and the easiest to work with and perform calculations on.

Here is how you create a column of date/time data in Excel (for an LJlogger data file):

1)  Insert a new column after A which Excel will call B.
2)  Put the formula "=1462-0.291666667+A4/86400" in B4, and then double-click on the black dot in the lower right corner of B4 to extend the formula to all cells of column B.  Note that -0.291666667 is the universal time adjustment for colorado (7 hours / 24 hours per day).
3)  Click on B to select the entire column, and go to "Format=>Cells=>Number".  Select "Date" for Category and select the desired Type. 



#3 Guest_Guest_*

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Posted 16 June 2003 - 07:36 PM

Great! Works like a charm! KenJ


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