Analog attribute state changes

Startup

• If the Access mode is Input or InputOutput, the value of the Value attribute is set to the default value for the attribute data type, the time stamp is set to the current time, and the quality is set to BAD.

• If the Field Attribute has only an output, the time stamp of the data value is set to the current time.

Going onscan

• If the Access mode is Input or InputOutput, then the Field Attribute value quality is set to INITIALIZING.

• If the Access mode is Output, the Field Attribute value is set to the initial state value and the value quality is set to GOOD.

• If the Access mode is Input or InputOutput, the time stamp of the Value attribute is set to the current time.

Execute

• If the Access mode is Input or InputOutput, read the new input value and quality and set it into the Field Attribute value.

• If a new Field Attribute value output is requested, and the Access mode is InputOutput or Output, the requested new Field Attribute value is written to the output location.

• Detect limit alarms, rate of change alarms, target deviation alarms and bad value alarms, if configured.

Going offscan

• If the Access mode is Input or InputOutput, the Field Attribute value quality is set to BAD and all alarm conditions are set to FALSE.

• If the Access mode is Output, the Field Attribute value and quality is set to the last written value. The time stamp is retained.

• If the Access mode is Input or InputOutput, the time stamp of the Value attribute is set to the current time if the quality changes because of a scan state change.

Offscan

The object is passive.

Shutdown

If references to field attributes were registered and suspended at startup, the references are activated and unregistered.