Scan State.  Tag field "SCANST" allows a user to put a tag in “maintenance mode” by setting this field to a desired value. This applies to IO tags, Constant, Calculation and Accumulation point Tags. Only I/O tags have the “bad” states (4 to 7).

0 is normal.

Set this value to:

1 to disable writes to this tag.

2 to disable alarm checking.

3 to disable writes & alarm checking.

4 to show value as BAD, '*' (asterisks), with quality 0xf0f0.

5 to show bad and disable write.

6 to show bad and disable alarm checking.

7 to show bad, disable write and alarm checking.

"Restore Tag Scan Status Timeout” can be defined in SCADA node properties. If the kernel re-starts with in the timeout, the kernel restores previous SCANST for the tag. If the kernel stopped normally, the last value is restored, otherwise, the last on-the-minute value is restored.