Understand attribute traits

Attribute traits identify commonly held characteristics or related behaviors of a parent attribute. PI AF supports attribute traits for limit conditions, forecasted values, geolocation information, reason codes, asset health, and analysis start triggers. Users and client applications like AVEVA PI Vision can then find, display, and analyze such related attributes more effectively.

To set and access attribute traits, both the PI AF client and server need to be running PI AF 2016 or later.

Limit attribute traits

You use limit attribute traits to identify the expected range of a process variable or a measurement attribute. Limit attribute traits are often set elsewhere (for example, on a control system), or represent inherent properties of the parent attribute, such as temperature. A typical usage would be to set up conditions for an alarm. AVEVA PI Vision, for example, uses most limit attributes as input when configuring multi-state behavior for a visual alarm.

Limit attribute traits are child attributes of the measurement they describe and have the same value type and UOM as the parent. The only exception is when the value of a limit attribute trait is obtained from a data reference, in which case the source UOM of a defined data reference can be different. You can also only set limit attribute traits for parent attributes that are numeric. Note that you can only assign a specific limit attribute trait once to a parent attribute.

The following limit traits are defined:

Video

For information on how to set limit attribute traits, watch this video:

Forecast attribute traits

In general, you use forecast attribute traits as predicted values to compare with the actual value of the parent attribute. Typically, such attribute traits represent future PI points but that is not a requirement. Client applications can very easily relate these attributes and trend them together.

Forecast attribute traits are child attributes of the attribute they describe and have the same value type and UOM as the parent. The only exception is when the value of a forecast attribute trait is obtained from a data reference, in which case the source UOM of a defined data reference can be different. You can also create forecast attribute traits for parent attributes that are of any value type. Note that you can have multiple forecast attribute traits defined for a parent attribute.

Location attribute traits

You use location attributes to define longitude, latitude, and altitude information for an asset. You can use this information to identify the location of the asset on a map.

You can create location attribute traits on an element, an event frame, a model, or on their child attributes. However, you can create only one of each attribute trait per element, event frame, or model. The UOM for the latitude and longitude attribute traits should be degree (the default) or at least an angle, whereas the altitude attribute trait can be meter (the default) or another UOM in the Length class. The value type for all location attribute traits must be numeric (double).

Reason attribute traits

You use reason attribute traits on event frames and transfers to enable users to select a reason code for excursions, downtime, and other events. You can set a single reason attribute trait on an event frame or transfer template or an event frame or transfer instance. The reason attribute trait must be an enumeration set that is previously defined, or a system enumeration set delivered with PI AF.

Health attribute traits

You use health attribute traits on elements and models to enable users to set a numeric health score and a health status (for example, healthy, out of service, in maintenance, warning, or error). The HealthStatus attribute trait uses values from the Health Status enumeration set, which is delivered with PI AF. Administrators can modify the Health Status enumeration set as required.

Analysis start-trigger attribute traits

When users configure analytics to generate event frames, they can optionally elect to store the name of the start trigger in the value of an attribute (string) and mark that attribute with the analysis start trigger trait. This enables clients like AVEVA PI Vision to indicate the start trigger that created that particular event frame. For more information, see Event frame generation analyses.