Deviation

Exception and compression deviation algorithms can be used to filter erroneous and redundant data before it is recorded in the archive.

Note: By default, future PI points have excmin, excmax and excdev turned off (set to 0).

Each algorithm is based on three specifications:

• Deviation in point value

• Minimum duration of time

• Maximum duration of time

• These specification are used to determine which points are recorded to the snapshot from the buffer (Exception) and to the archive from the snapshot (Compression).

  Note: Exception deviation and compression deviation filter externally-generated events for archiving. Under no circumstances does this cause Data Archive to generate events.