Tag types

Tag definitions

A tag definition is a reference to data that is usually measured usually comes from a data source such as a data historian. Historians may also use the term tag to refer to the measured data values that they collect. The Tag definitions in AVEVA Production Accounting are a way of mapping concept of a tag to a tag in an external historian.

Tags can refer to all kinds of measurement data such as flow rates, volumes, densities, component information, temperatures, pressures, etc.

Different configuration objects can share one tag definition, i.e. refer to the same tag definition in order to make use of the same externally available data. For example, densities are often measured at one point in a plant that would apply to several streams. In concrete terms, a density tag DEN1 might therefore be used for both Stream A and Stream B objects.

Tag types

There are two types of tags: historian tags and logical tags. Logical tags are part of the Smart objects feature and use formulas to derive their values.

• Historian tags obtain their values from an external data source such as Honeywell’s PHD historian or AVEVA PI System. Historian tags will only work correctly if you define an interface to the appropriate historian as described in Edit Interface Info.

• Defining Logical Tags is described in full in Edit Logic Info. The rest of the current section will focus on historian tags.

When you right-click the row header in the No. column, a context menu appears as shown in the screenshot below. This menu lets you copy and paste selections as well as add, insert and delete tags. The Copy and Paste commands move selections to and from the Windows Clipboard to copy and paste between a grid and a spreadsheet in Excel, for example.