The instrument tag 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 the instrument tag is used to identify a point, address or location on the data source. If an interface uses the instrument tag for this purpose, the interface manual will have a detailed description of the requirements for this attribute.
DigitalSet
The DigitalSet attribute is used to assign a digital state set to a PI Point. For standard usage, refer to PI Server Reference Guide.
PI Tag String Attribute Limits
UniInt retrieves three string type attributes from the PI server during point loading other than the point source which is described above. The three attributes are the tag name (Tag), extended descriptor (ExDesc) and the instrument tag (InstrumentTag). The instrument tag is not used by UniInt, but the string value for this attribute is sent to the interface during point loading. The extended descriptor is checked by UniInt for a number of key words that may identify the point as a UniInt point. The extended descriptor is also passed to the interface during point loading. The tag name is only used for logging error and debugging messages. UniInt saves a maximum of 21 characters for the tag name after point loading is completed. If the tag name is longer than 21 characters, UniInt will save the first ten characters and the last ten characters of the tag name separated by a tilde (~). If the tag name length exceeds the number of characters UniInt can retrieve, the last ten characters will be the last ten UniInt is able to retrieve during point loading. The number of characters UniInt can retrieve for each attribute depends on the PI API version, the PI Server version and whether or not the PI SDK is being used to retrieve point attributes. The following table describes the number of characters UniInt can retrieve given the configuration. The first column of the table is “new API functions”. The new API functions that support retrieving the longer attributes are only available if the PI API is version 1.6.x or higher AND the PI Server is version 3.4.370.x or higher. Please consult the interface documentation to determine if the interface requires UniInt to load the PI SDK. If the –PISDK startup parameter is not specified by the interface, the value is 0.