Question: Why doesn’t my time stamp show the time to the millisecond it was collected at?
To be clear, DAQami and TracerDAQ do show the time stamp down to the one-over-sample rate the data was collected, but Microsoft Excel doesn’t automatically show you the correct time format.
To verify this, collect a few seconds of data at a sample rate of 1000 samples per second on one channel using either DAQami or TracerDAQ/TracerDAQ Pro. When the acquisition ends, right mouse click on the .csv file and click on “Open with”, then select Notpad or Wordpad.
I ran this test, here is the first few lines from the .csv file when opened with Notepad:
"Device: USB-1208LS"
"Serial Number: 182F8FE"
"Channel Count: 1"
"Sample Count: 6784"
"Start Time: 10/6/2016 2:53:18 PM"
"Sampling Interval: 0.000998003992015968"
"Sample","Date/Time","AI0 (V)"
"0","10/6/2016 2:53:18.2834 PM","2.05"
"1","10/6/2016 2:53:18.2844 PM","2.05"
"2","10/6/2016 2:53:18.2854 PM","2.05"
"3","10/6/2016 2:53:18.2864 PM","2.05"
"4","10/6/2016 2:53:18.2874 PM","2.05"
"5","10/6/2016 2:53:18.2884 PM","2.05"
"6","10/6/2016 2:53:18.2893 PM","2.05"
"7","10/6/2016 2:53:18.2903 PM","2.05"
As you can see, I have underlines the time stamp shows the time down to the 4th significant digit of a second.
Opening the same file in Excel, shows this:
Here the time stamp does indicate time to the millisecond But it can be reformatted by right mouse clicking on the ‘B’ column header, and select ‘Format Cells…’
In the Category column select “Custom” and then in the “Type:”select m/d/yyyy h:mm. We can modify this by adding a few more characters by adding :ss.000 to the type so that the final format will be:
m/d/yyyy h:mm:ss.000
and now the data looks like this:
Time to the millisecond is the most accuracy Excel allows.