PI-API (Integration)
The PI System is designed to work in a secure network environment. PI System components, the PI Data Archive (PI-DA), the data Interfaces (PI-IF) to data sources and the client tools (e.g. PI-PB, PI-PC, user applications) all exchange data using the same set of software routines described as the PI Application Programming Interface (PI-API).
The PI-API is a collection of standard software routines to access the PI System. It spans a wide range of hardware and software platforms and provides a common programming interface to PI information from the Point Database, the Archive, and PI Tables, as well as providing utilities for interface and user-application development.
The PI-API is divided into sections based on the nature of each function's activities. For example, all functions that access or modify the Data Archive in some fashion belong to Archive Functions, while all functions that access or modify the Point Database belong to Point Database Functions, etc. Other functions include PI Batch, Event Log, Message Log, Snapshot, Time and Utility and Extended functions.
Data buffering is supported in the PI-API. This feature makes sure that no data are lost when an interface loses its connection to the home node. This feature has been added to the PI-API so that all PI System platform interfaces automatically gain buffering support upon a re-link.
The PI-API also includes functions to send and receive sub-second timestamps. These functions are called the Extended PI-API functions. They work with PI servers on Windows NT and Unix platforms. The sub-second functions on OpenVMS platform are rounded off and values are coerced to PI on OpenVMS point types.
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