UniInt End User
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PI BASemAPI
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- PointSource
- Case-sensitivity for PointSource Attributes
- Reserved and Illegal Point Sources
Point AttributesThe following PI point attributes are used by UniInt based interfaces. Refer to the interface documentation to determine whether the standard UniInt implementation for a particular attribute is applicable. Some attributes may have additional or different meanings for individual interfaces. If the specific attribute is not mentioned by the interface documentation of a UniInt based interface, then the attribute will affect the data in accordance with the explanation in this manual. Also, most UniInt based interfaces use a number of attributes that are not described here. TagThe words point and tag are frequently used interchangeably, but there is a difference. A tag is a label or name for a point. Any tag name can be used in accordance with the normal PI point naming conventions. PointSourceThe PointSource is a unique, single or multi-character string that is used to identify the PI point as a point that belongs to a particular interface. For example, a single point source using the letter R may be chosen to identify points that belong to the Random interface. In order to implement this, the PointSource attribute should be set to R for every PI Point that is configured for the Random interface. Then, if /ps=R is specified on the startup-command-line of the Random interface, the Random interface will search the PI Point Database for every PI point that is configured with a PointSource of R. Likewise, a multi-character PointSource using the string Boiler1 may be used to identify points that belong to the PIIFC Interface. To implement this, the PointSource attribute would be set to Boiler1 for every PI Point that is configured for the PIIFC Interface. Then, if /ps=Boiler1 is used on the startup command-line of the PIIFC Interface, the Interface will search the PI Point Database for every PI point that is configured with a PointSource of Boiler1. Before an interface loads a point, the interface usually performs further checks by examining additional PI point attributes to determine whether a particular point is valid for the interface. For additional information, see the /ps parameter. The following table explains length limits imposed on the PointSource for different configurations. When the maximum possible lengths differ for the software installed on site, the shortest length applies.
Case-sensitivity for PointSource AttributesIn 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. The case of the PointSource is only a concern during point definition, and only if the interface will be running on a PI 2 PINet node communicating to a PI 3 Server. There is no need to create a point source table on a PI 3 Server, which means that points can be immediately created on PI 3 with any point source character. Reserved and Illegal Point SourcesSeveral subsystems and applications that ship with PI 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. OSIsoft recommends not using these point source characters. Also, if a point source character is not specified when creating a PI 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. Download 1.93 Mb. Share with your friends:
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