"Totalizer" for a historical value

All - we are needing to build a “totalizer” for a historical tag. I’ve been told that this can be done with an Expression Tag, but I am new to the Ignition platform so, if there’s a better method, I’m open.

Basically, we have a boolean tag, MACHINE_IS_RUNNING, which has history enabled. What we would like to determine is total machine run time.

Hope that’s enough info.


You can use an Hour Meter Transaction Group (https://www.inductiveuniversity.com/videos/hour-and-event-meters/8.0) to log the run time.

Good stuff! I was able to set up the transaction group with an hour meter, which is logging to the database as expected. To expose the “total run time”, I have a separate query tag (outside of the transaction group), running at set intervals, which takes the value of the most recent record from the table. Any recommendations on a better way to do this? I was hoping I could set this separate tag within the transaction group, but did not immediately see how. Thanks!