UniInt End User
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PI BASemAPI
TypicalValueAlthough the TypicalValue is only used to document a reasonable value for the PI point, it must be specified if its default value will not fall between the Zero and Zero+Span. Otherwise, creation of the PI Point will fail. For a numeric tag, it must be greater than or equal to the Zero attribute and less than or equal to the Zero attribute plus the Span attribute. The TypicalValue must be between Zero and Zero plus Span. For digital points, PI sets the Zero and Span internally. See the description of Zero and Span attributes for more information. SourceTagThe SourceTag attribute is used to designate a trigger tag for output points. The mechanism by which a SourceTag is used to trigger outputs is discussed under the section called “Output Points,” page 23. ShutdownThe shutdown attribute is used only if the server node is a PI 3 system. The Shutdown attribute is 1 (true) by default. The default behavior of the PI Shutdown subsystem is to write the SHUTDOWN digital state to all PI points when PI is started. The timestamp that is used for the SHUTDOWN events is retrieved from a file that is updated by the Snapshot Subsystem. The timestamp is usually updated every 15 minutes, which means that the timestamp for the SHUTDOWN events will be accurate to within 15 minutes in the event of a power failure. For additional information on shutdown events, refer to the PI Buffer Server.chm file. Note: The SHUTDOWN events that are written by the PI Shutdown subsystem are independent of the SHUTDOWN events that are written by the interface when the /stopstat command-line parameter is specified. SHUTDOWN events being written to PI can be disabled when PI is restarted by setting the Shutdown attribute to 0 for each point. Alternatively, the default behavior of the PI Shutdown Subsystem can be changed to write SHUTDOWN events only for PI points that have their Shutdown attribute set to 0. To change the default behavior, edit the \PI\dat\Shutdown.dat file, as discussed in PI Server Reference Guide. It is undesirable to write shutdown events when buffering is being used. Bufserv and PIBufSS are utility programs that provide the capability to store and forward events to a PI Server, allowing continuous data collection when the Server is down for maintenance, upgrades, backups, and unexpected failures. That is, when PI is shutdown, Bufserv will continue to collect data for the interface, making it undesirable to write SHUTDOWN events to the PI points for this interface. Disabling Shutdown is recommended when sending data to a Highly Available PI Server Collective. Refer to the Bufserv manual for additional information. ExDescThis is the extended descriptor attribute. The extended descriptor is a string attribute. Please refer to the PI Tag String Attribute Limits section beginning on page 21 for a description of the maximum number of characters available to the interface for different configurations. Typically, if the extended descriptor is used by an interface, it is used to identify a point, address or location on the data source. If an interface uses the extended descriptor for this purpose, the interface manual will have a detailed description of the requirements for this attribute. UniInt uses the extended descriptor to identify Performance Points (page 26), Trigger Tags (page 22), Failover Control Tags (page 75) and Interface Health points (page 24). Download 1.93 Mb. Share with your friends:
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