Logstash/grok to match only first occurrence and stop parsing repeatedly for same values

That's helpful.

i have to calculate time difference between these two events as well, should i continue here or open a new topic?

Was looking into the forum for time difference between two timestamps and found one post in which you posted a solution, but that isn't working for me.

For reference, the same sample log ( as posted above ) , i need to get the total time in minutes and hours between two different readings. For example, how much time did the device stayed at 20.1 and 20.3 and so on.

please advice,