Summary states are skill data points that summarize the value of a series of data points and/or skill data points that contain Boolean states (true/false, on/off etc.). The values of these input states are combined using either a logical OR operation, or a logical AND operation. A summary state that uses an OR operation will be set if any of the inputs are set. A summary state that uses an AND operation will be set if all of the inputs are set.

The resulting state can optionally be inverted, meaning that set and unset are swapped. An inverted OR summary state will thus be unset if any of the inputs are set, and an inverted AND summary state will be unset if all of the inputs are set.

A summary state can use numerical as well as Boolean data points as inputs. For numerical data points, a value of 0 is interpreted as false, and any other value is interpreted as true.

Summary Alarms

Summary states that use the logical OR operator are often used be used to create summary alarms. The summary alarm will be set (true) if any of the individual alarms it summarizes is set. The same can be done to summrize warnings and other states.

Accessing Summary States

Summary states have the following members:

Attributes

key	The summary state’s primary key.
name	The summary state’s name. The name is the last component of the primary key.
UUID	The unique UUID of the summary state.
type	The summary state’s element type. For summary states, this is always “summary state”.
category	The summary state’s category. For summary states, this is always “data point”.
value	The summary state’s value.
updateTime	The last time the value was updated.
changeTime	The last time the value changed.
quality	The quality of the current value.
error	If the quality attribute is anything but “good”, this attribute contains the error that caused the quality to degrade.

Events

changed This event is raised when the value, the quality, or the error changes.