Point Attributes

All of the standard pi point attributes are accessible through functions in the PI-API.

Long Tagnames

The PI Data Archive has added support for long tagnames, i.e., tags up to 80 characters in length.

Note: UNIX and Windows NT systems support tag names of unlimited length.

To provide compatibility with existing applications, the tagname was not made obsolete by the long name; consequently, a given PI point can have two unique tag identifiers. The tagname is required, while the long tagname is optional. Since both the tagname and long tagname are considered valid point identifiers, tag searches include both.

Note: The PI-API assumes if a long tagname has been defined, then the long tagname is the preferred method to reference the point.

Backwards compatibility has been maintained with clients and servers that do not support long tagnames.

Three functions are provided specifically for retrieving tag names given a point. pipt_tag is used to retrieve the short tag name; pipt_taglong is used to specifically retrieve the long tag name; pipt_tagpreferred is provided to retrieve the long tag name if one is defined, otherwise the short tagname is returned.

On Windows NT and UNIX systems, all three functions return the point’s tag property which may be of any length. These functions will truncate the tag if the character buffer passed is of insufficient length to hold the full name.

Point Updates

A mechanism to notify applications of changes in the Point Database is provided through the functions pipt_signupforupdates and pipt_updates..

Tag Search

The function pipt_wildcardsearch provides an application with an alphabetized listing of points that match a specified tag mask.

Enabling Operational Intelligence