Rockwell Automation FactoryTalk Historian SE ProcessBook 3.2 User Guide - Manual (Page 290)

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FactoryTalk Historian ProcessBook User Guide
272
ODBC Data Sources
An ODBC data source identifies a database a user wants to access and the
information needed to connect to that data. Examples of ODBC data
sources are:
 A SQL Server database, the server on which it resides, and the
network protocol used to access that server.
 An Excel spreadsheet on a file server.
 A directory containing a set of dBASE files you want to access.
ODBC data sources have an explicit name, are configured for a particular
computer, and may be used by any ODBC- compliant application installed
on that computer.
ODBC Data Access
FactoryTalk Historian ProcessBook stores relational queries in data sets
within ProcessBook files. The data sets are created, stored, and accessed by
name. FactoryTalk Historian ProcessBook symbols can then access the
data sets. The columns in the data set make up the items that can be
assigned to the trend, value, or bar. The SQL needed to retrieve data for
FactoryTalk Historian ProcessBook can be configured once and used by
many displays and symbols.
FactoryTalk Historian ProcessBook must return a time and value pair(s)
for display within a symbol (trend, value, or bar). Placeholders act as
parameters to an SQL function call. They are evaluated at run time.
Placeholders can take three forms: text, start/end times, or a FactoryTalk
Historian tag name. Use the start and end time placeholders when the time
limits of the query should be determined from the trend symbol where the
query is used. The FactoryTalk Historian tag name placeholder can be used
to join FactoryTalk Historian data with relational database data. A
FactoryTalk Historian Value is retrieved for the FactoryTalk Historian tag
and then substituted into the query.