Containment vs​. attributes

Using containment or attributes as the best configuration approach depends on actual field device requirements.

For example, template containment works best when the lower level object also has many components and may contain even lower-level objects.

Similar functionality can be achieved using attributes. However, when the lowest level object is added to a template, it may be done using either template containment or attributes. Both support an external I/O point link and history.

Use the following general guidelines to expedite an appropriate development strategy:

• Use template containment when more functionality is required, such as complex alarms, setpoints, I/O points, or other features readily available in a template.

• Use attributes when the lower-level object is very basic.

• Use attributes for memory or calculated values.

Decide the appropriate approach in advance of implementation.

Best Practice

• Ensure the container incorporates functionality. Otherwise, place it as an attribute in another object. Do not use excessive empty containers simply as placeholders to host objects. Empty containers impact engine scan resources and time.

• Up to 5,000 attributes can be added to an object. If you add a description to the object, however, this number is cut in half owing to the fundamental structure of objects.

• Deeply-nested template/container structures slow down object check-in and propagation.

• Complex objects should be built using attributes, scripts and containment.

  The form supported by Application Server is a .NET Library and can be created using Visual Studio .NET with either Visual Basic .NET or Visual C# .NET.

  Note: The Application Object Toolkit can be used to create custom templates.