Doubts about Historical

Good Morning.

  1. In a Easy Chart, in the “Tag History Resolution Mode”, which is the different between Natural and Raw mode. Can you explain it with an example, please?


  1. If a Tag Group (Scan Class) is configured to historize tags with Direct mode, then the History options are ignored? I understand that the tags will be recorded at the indicated rate, regardless of the Min Time and Max Time.


Best regards.

Natural means that the results dataset will have a value corresponding to each expected execution of the scan class. Due to the historian’s storage optimization, there won’t be an actual row of data in the database, but natural mode will essentially ‘reverse’ the storage optimization and give you a point of data for each expected row per the scan class.

Raw mode will return only the actual data that is stored in the database. You can still reverse this into the expected results by reversing the sliding window algorithm yourself, but it’s probably easier to do use ‘natural’ mode if you expect to use this data elsewhere.

Not exactly. When driving tag history, the scan class indicates how often the system should decide to store a point - but a rate of 1 second (or 10 seconds, or anything else) does not, by itself, mean that a data point will actually be stored into the database every 1, 10, etc seconds.
That manual page goes into more detail. The short version is you can override the sliding window algorithm behavior to force an actual row to be logged by using the min/max time settings.