Counter like tag with cumulated value

Ignition
12

The reliable way to do this is to record state changes in an event table. Then use LEAD or LAG functions in the DB to get intervals per state, clipping to the start of shift. Sum those intervals while grouping by state. With an index on t_stamp, your DB will calculate this blisteringly fast.

Select state, sum(event_duration) as duration
From (
  Select state, nextTS - clipped as event_duration
  From (
    Select state
      , case t_stamp < :shift_start_ts then :shift_start_ts else t_stamp end as clipped
      , coalesce(lead(t_stamp) over (Order by t_stamp), current_timestamp) as nextTS
    From state_events
    Where t_stamp >= (Select max(t_stamp) Where t_stamp < :shift_start_ts)
  ) intervals
) durations

Display the final duration from the row that matches the current state.

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