Rockwell Automation FactoryTalk Historian SE 3.0 UniInt Interface User Guide - Manual (Page 36)

Interface Operation
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be established before the interface will continue. If the interface is started while the Historian
Server is down, the interface will try to establish the connections until the Historian Server is
up.
Historian Point Updates
When a UniInt-based interface starts, the interface searches the Historian Point Database for
points that belong to the interface (see the PointSource attribute under ―Historian Point
Configuration‖) and a point list is created for the interface. Once startup is complete, UniInt
checks the Historian Point Database every 2 minutes for points that are added, edited, and
deleted. If point updates are detected, the points are loaded (or reloaded) by the interface as
appropriate. The 2 minute update interval can be adjusted with the /updateinterval command-
line parameter.
UniInt will only process 25 point updates at a time. If more than 25 points are added, edited,
or deleted at one time, UniInt will process the first 25 points, wait 30 seconds (or by the time
specified by the /updateinterval parameter, whichever is lower), process the next 25
points, and so on. Once all points have been processed, the interface will resume checking
for updates every 2 minutes (or by the time specified by the /updateinterval parameter).
UniInt will write the digital state SCAN OFF to any points that are removed from the
interface while the interface is running.
Exit Handler
UniInt‘s exit handler performs the following operations in the listed order.
1. UniInt calls the interface-specific exit handler to perform interface-specific cleanup
operations.
2. If the /stopstat=digstate parameter is present on the command-line of the
interface, UniInt will write the digstate, digital state, to all scan-based and event-
based input points of the interface. If a performance point is associated with the
interface, digstate will also be written to the performance point. I/O Rate points do
not receive digstate events because 0 is written to I/O Rate points when the interface
exits. See the description of the /stopstat parameter under the section called ―The
Startup Command File‖ for recommended usage of the /stopstat parameter,
3. If an I/O Rate point is associated with the interface, the I/O Rate point will be updated
with a final rate, and the I/O Rate counter will be zeroed.
It is possible for the interface to be terminated without invoking the exit handler. One
normally does not want to bypass the exit handler. On any operating system, the exit handler
will not be invoked when the computer crashes. For interactive processes on Windows, the
exit handler will be terminated prematurely if control-c is hit a second time (the exit handler
is invoked the first time that control-c is hit).