Attributes tab classic Row Edit dialog box

Point Security

This field specifies who has access to a point's data values (Snapshot and Archive data).

Data Security

This field specifies who has access to the point's configuration (Zero, Span, Descriptor, etc.)

Enable compression

A Boolean value: Select checkbox (1) to enable compression, or clear checkbox (2) to disable compression.

Compression deviation Value

An event is archived in two circumstances:

• If the elapsed time since the previous event is greater or equal to the Compression time minimum and the value has changed by more than the Compression deviation Value.

• If the elapsed time is greater than the Compression time maximum. (It is recommended to set compmax to one work shift e.g. 8 hours.)

  Note: Compdev specifies the compression deviation in engineering units.

Compression time maximum

Compression time minimum

Compression time percentage

Specifies the compression deviation as a percent of Span. If you change one of compdev or compdevpercent, the other is automatically changed to be compatible. If you try to change both at once, compdevpercent takes precedence.

Exception deviation amount

An exception is sent in two circumstances:

• If an event occurs and the time since the last event is greater or equal to the Exception minimum time and the value has changed more than the Exception deviation amount.

• If an event occurs and the elapsed time is greater than the Exception maximum time.

  Notes: The Exception deviation amount should be less than the Compression deviation amount by at least a factor of 2.

  Excdev specifies the exception deviation in engineering units.

Exception time maximum

Exception time minimum

Exception deviation percentage

Specifies the exception deviation in percent of Span. If you change one of excdev or excdevpercent, the other is automatically changed to be compatible. If you try to change both at once, excdevpercent takes precedence.

Enable archiving

A Boolean value: Select checkbox (1) to enable archiving, or clear checkbox (2) to disable archiving.

Step interpolation

A Boolean value: Select checkbox (1) to treat archived values discretely; an archived value is assumed constant until the next archived value. Clear checkbox (2) to treat archived values as a continuous signal; adjacent archived values are linearly interpolated. For example:

• At 12:00:00, the value 101.0 is archived.

• At 12:01:00, the value 102.0 is archived.

  If stepflag is on a request for the archive value at 12:00:30 would return 101.5. If stepflag is off a similar request would return a value of 101.0.

Note: Stepflag also affects the compression calculation. When on, a linear change of value greater or equal to compdev passes compression. When off, the complete swinging-door algorithm is applied.

Enable Scan

If this checkbox is cleared, the PI-OASyS interface will not retrieve the value for the tag.