I have 3 columns that have date/time on the first column and device status on the 2nd column and calculated Time difference on the third column. I have sample data below.

I have to subtract the first instance of ENABLE DEVICE DATE/TIME from the previous MALF DEVICE DATE/TIME to get the difference. I do not worry about the DISABLE Device date/time at all. I could do this manually but there are about 20,000 records to go through. I don't know if there is a worksheet function that will do this automatically for me.


Date/Time DEVICE STATUS TIME DIFFERENCE
6/7/04 6:59:48 MALF DEVICE
6/7/04 7:32:44 ENABLE DEVICE 0:32:56
6/17/04 12:23:25 MALF DEVICE
6/17/04 12:33:10 DISABLE DEVICE
6/17/04 12:35:37 DISABLE DEVICE
6/17/04 12:35:59 ENABLE DEVICE 0:53:48

Any help will be appreciated.