Honeywell Uniformance R300, User Manual

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4 Overview of Uniformance PHD
4.2 PHD Server Functionality
Uniformance PHD OPC Server User Guide
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4.2 PHD Server Functionality
The Uniformance PHD Server is an autonomous server that maintains historical archives of
process variables and other related data samples. Data values are stored in the PHD history
database by application programs and through periodic collection from control systems.
The PHD Server uses a configuration database containing the descriptive information, such as
name, data type, source RDI, collection rate, and so on, for each data parameter. This
database may also contain the identities and access privledges of individual users who can
access the values stored for each variable. The database is hosted by a SQL Server RDBMS.
The RDBMS may be physically hosted by the same computer as the PHD Server, or it may be
on another system.
The PHD Server maintains data samples for each point variable in a data cache in memory,
and periodically flushes its contents to the history archive files. The data cache contains the
most recent values input to PHD for each point variable.
Data can be placed in PHD history storage by application programs, such as statistical
analysis and laboratory data collection software.
Periodic data collection and input to the PHD Server historical database is also performed by
Real-time Data Interfaces (RDIs). Each RDI, such as an interface to a DCS, encapsulates the
data access mechanism compatible with the specific system to which it interfaces. You can
configure multiple RDIs to collect data from a multitude of Honeywell or other vendor DCS,
Laboratory, PLC, or other process related systems.