Before building templates, identify and document the functional requirements of the target field device.

To accomplish this, the following tasks must be completed:

• Identify all required field device properties (attributes). They include names, data types, and interaction requirements (that is, none, input, output, or input/output). For each attribute, determine if:
  • The attribute requires scaling or uses raw values.
  • The attribute requires alarms, and the alarming model to be used by each. This model can include where the alarms will be generated (locally or in the control system), any alarm priority assignment, and alarm messaging needs.
  • The attribute requires security and the security control.
  • The attribute requires historical logging. For example, is forced data storage required? For a variable data type, do you need to define the trend limits and a deadband?
• Identify any required scripting, such as algorithms, interaction between devices, and so on.
• Determine if field devices are grouped either into a common template or into a containment template model.

It is not necessary to know all requirements before building a template model. Extra functionality can be easily implemented in the template when new requirements are determined.