Rockwell Automation 9301 Series RSView32 Users Guide - Manual (Page 204)

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RSView32 User’s Guide
Choosing between narrow and wide .dbf file
formats
The following table summarizes the features of each file format:
Date1 Time1 Tag1 value Tag2 value Tag3 value
Date2 Time2 Tag1 value Tag2 value Tag3 value
Date3 Time3 Tag1 value Tag2 value Tag3 value
Date4 Time4 Tag1 value Tag2 value Tag3 value
Date5 Time5 Tag1 value Tag2 value Tag3 value
Date6 Time6 Tag1 value Tag2 value Tag3 value
This is one
snapshot of data.
Narrow Wide
Limit of 10,000 tags in the model. Limit of 100 tags in the model.
Most useful for storing data that
changes infrequently (as in on–
change logging). Most useful for storing frequently
changing data (as in periodic
logging). Particularly useful for
storing data from batch
applications.
Data is harder to use for sums and
averages because it crosses rows. Data is more easily used for sums
and averages because it is all in one
column.
Does not create a new log file set if
tags are added to or deleted from
the model. Creates a new log file set if tags are
added to or deleted from the
model.
Stores numeric and string values in
separate files. Stores numeric and string values in
the same file.
Preferred for queries because you
can join tables. Can’t join tables for queries.