Tag

The Tag attribute (or tagname) is the name for a point. This tag is assigned to the condition, which is unique within the server (for example, PI-tag “Boiler1LevelAlarm” assigned to Boiler1.FIC1001 within the OPC AE server). There is a one-to-one correspondence between the name of a point and the point itself. Because of this relationship, PI System documentation uses the terms “tag” and “point” interchangeably.

Follow these rules for naming PI points:

• The name must be unique on the PI Data Archive.

• The first character must be alphanumeric, the underscore (_), or the percent sign (%).

• Control characters such as linefeeds or tabs are illegal.

• The following characters also are illegal: * ’ ? ; { } [ ] | \ ` ' "

Length

Depending on the version of the PI API and the PI Data Archive, this interface supports Tag attributes whose length is at most 255 or 1023 characters. The following table indicates the maximum length of this attribute for all the different combinations of PI API and PI Data Archive versions.

If the PI Data Archive version is earlier than 3.4.370.x or the PI API version is earlier than 1.6.0.2, and you want to use a maximum tag length of 1023, you need to enable the PI SDK.