Rockwell Automation FactoryTalk Historian SE 3.0 UniInt Interface User Guide - Manual (Page 23)

UniInt Interface User Manual 17
PI API Historian Server PI SDK Maximum Length
na Below 2.x Disabled 1
Below 1.6 na Disabled 1
na na Enabled 100
Case-sensitivity for PointSource Attributes
In all cases, the point source character that is supplied with the /ps command-line parameter
is not case sensitive. That is, /ps=P and /ps=p are equivalent.
Reserved and Illegal Point Sources
Several subsystems and applications that ship with Historian 3 are associated with default
point source characters The Totalizer Subsystem uses the point source character T, the Alarm
Subsystem uses G and @, and the Performance Equations Subsystem uses C. Rockwell
Automation recommends not using these point source characters. Also, if a point source
character is not specified when creating a Historian point, the point is assigned a default
point source character of Lab. Therefore, it would be confusing to use L or Lab as the point
source character for an interface.
The * and the ? characters are invalid point sources as they are wild card characters for
searching the database. These characters cannot be any part of a multi-character point source.
PointType
Consult the interface documentation to determine which point types are supported for
individual interfaces. Not all point types that are supported by the Server are necessarily
supported by an interface.
Typically, DCS point types do not need to correspond to Historian point types but this may
be a requirement for certain interfaces. For example, integer values from a DCS can be sent
to floating point or digital Historian tags. Similarly, a floating-point value from the DCS can
be sent to integer or digital Historian tags, although the values will be truncated. This rule
does not extend to string tags. UniInt will not convert an integer, float, or digital type value
to a string. Unless the interface documentation specifies these conversions, only string and
blob type data will be saved to a string Historian tag.
Note: If an interface is not using the extended PI API functionality, negative integer
values from the DCS must be stored in floating point tags in Historian because
negative integers cannot be transmitted by the traditional PI API. If using the
extended PI API, int16 and digital tags are the only Historian point types with this
limitation.
ExcMin, ExcMax, ExcDev and ExcDevPercent
These are the exception specification attributes.