This document describes extensions to the pi Application Programming Interface (PI-API) to support some of the features of the PI System for Windows NT and UNIX.
The extended PI-API includes functions to manipulate sub-second timestamps, retrieve detailed point type information, and to access data values in the PI System Snapshot and Archive.
All extended PI-API functions can also be used for communicating with a PI System for OpenVMS.
The extended PI-API functions are not available in the OpenVMS PI API library.
Interface developers should take note of the pisn_putsnapshotx Usage Notes, which describes the rules for inserting new data values into PI using the extended PI-API.
Features of PI for Windows NT and UNIX
The extended PI-API functions provide support for string-valued points and for sub-second timestamps for all data values. These features are supported only by the PI System for Windows NT and UNIX. These functions can also be used for reading and writing integer, digital, and floating point values.
Features of PI for VMS
The extended API functions can also be used in interacting with the PI System for OpenVMS, where possible. This means that data retrieved from PI for OpenVMS using the new functions will lack a sub-second portion. String-valued points do not exist on PI for OpenVMS.