Need Help - The time entry is happening continuously - need to calculate only valid Time

Hi experts,

I have this file, which will update Time stamp once desktop locked (start time) and Unlocked (end time).
Time entry will happen one after the other.

In the next column i have updated formula to minus End time with Start time to calculate actual time.

example,
1st row B1 will have Start time
2nd row B2 will have end time

while when system locked again,

3rd row B3 will have Start time
3rd row B4 will have End time
by the formula that i have given in C column , i am not getting actual time.

I dont want my formula to calculate time difference between b3 and b2
as B3 is part of 2nd set. And B2 is part of 1st set.

I couldnt differentiate these...... can somebody help to get a work around on this.

Attached sample file for reference. Given comments in the File highlighted with Red colour, which i dont want to be summed.

Please help, I need this help desperately.

HI BoredWorker,

Appreciate your response.

Not sure how to do it, because the actual time difference will also be not equal to 5 sec.

i dont want the time difference of End time of first set and start time of second set of entry.

just gone crazy what to do.

Post #1 states that end time is time stamped when desktop is unlocked, yet all of the entries in column A read 'Locked', so how do you know when one set ends and another begins?
That said if all of the 'Locked' time differences will be consistent then you could modify the formula for C2 and down to read: =IF(ISBLANK(B3),"",MROUND(B3-B2,1/86400))
You could then sum the 'Locked' times using: =SUMIFS(C2:C20,C2:C20,MODE.SNGL(C2:C20))
In the file attached to post #1 this method yields 1:20
Let us know if you have any questions.