Phases upon deployment

Startup

• If output is configured, the initial attribute value is used as the initial value of OutputDest, and the time stamp of the data value is set to the current time.

• If input is configured, the initial value of the Value attribute set to the default value of the attribute, the time stamp is set to the current time, and the quality is set to BAD.

Going onscan

• If the I/O feature is set to "Read from" or "Read from/Write to," then the value attribute quality is set to INITIALIZING and the time stamp is set to the current time.

• If the I/O feature is set to "Write to" or "Read from/Write to," the value attribute is set to the initial value and the value quality is set to GOOD.

Execute

• If the AccessMode is Read (Input) or Read/Write (InputOutput), read the new input value and quality and set it into the Attribute value.

• If a new Attribute value write (output) is requested, and the AccessMode is Read/Write or Write, the requested new Attribute value is written to the output location.

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

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

Going offscan

• If the AccessMode is Read or Read/Write, the Attribute value quality is set to BAD and all alarm conditions are set to FALSE.

• If the AccessMode is Write, the Attribute value and quality is set to the last written value. The time stamp is retained.

• If the Access mode is Read or Read/Write, 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 attributes were registered and suspended at startup, the references are activated and unregistered.

Script

For Startup, On Scan, Off Scan and Shutdown execution types, scripts execute when those events occur for the object being configured. For the Execute execution type, the script executes when the Expression, Trigger Type, Trigger Period and/or Deadband values are satisfied within the context of the object's scan period.

Scripts cannot be triggered any faster than the scan period of the engine upon which the script runs.