Rockwell Automation FactoryTalk Historian SE 3.0 UniInt Interface User Guide - Manual (Page 55)

UniInt Interface User Manual 49
Interface Disconnected Startup
Interfaces built with UniInt version 4.3.0.x or later include functionality to take advantage of
the Disconnected Startup operation. Simply stated, disconnected startup allows the interface
to start from a local cache file with or without a valid connection to the host Historian
Server. This critical functionality prevents data loss when an interface needs to start up and it
does not have a connection to the Historian Server.
In addition, even if a connection to the host Historian Server is available, if the interface is
configured for disconnected startup, the interface will utilize the local cache to quickly get
the interface started and collecting data from the Data Source. Using the disconnected startup
feature when a Historian Server connection is available bypasses potentially long delays
caused by the latency in network calls required to gather point information from the
Historian Server, which in turn delays the ability of the interface to begin data collection
from the Data Source. As an example, an interface with 50,000 associated Historian Points
may take several minutes to retrieve all the Historian Points from the Historian Server. Using
the disconnected startup feature can reduce the interface time to load the same 50,000
Historian Points from the cache file to approximately 10 seconds. Results will vary
depending on the system architecture and network latency. However, using disconnected
startup will improve interface startup time, especially when large point counts are being
used.
The first time the interface is started with the disconnected startup parameter, a connection to
the Historian Server will be required to populate the cache files with the necessary data to
support the disconnected startup feature on subsequent interface restarts. Two local cache
files will be created on the interface node. The time to startup will be delayed while these
files are being created. The local cache files contain the required Historian Server version,
Historian point configuration, and Digital State information needed to start the interface.
Once started, the interface can actively collect and buffer data retrieved from the Data Source
when no connection to the host Historian Server is available.
Disconnected Startup Requirements
The minimum requirements necessary to run a UniInt based interface in a disconnected
startup configuration are as follows:
Operating Systems

Windows: Server 2003, XP Pro SP2, 2000 Server SP4