The SupportInfo Interface defines a number of additional data that a commonly exposed for Devices and their components. These include mainly images, documents, or protocol-specific data. The various types of information is organized into different folders. Each information element is represented by a read-only Variable. The information can be retrieved by reading the Variable value.
Figure 8 – Support information Interface
Table 23 – ISupportInfoType definition
Subtype of the BaseInterfaceType defined in OPC 10001-7
Clients need to be aware that the contents that these Variables represent may be large. Reading large values with a single Read operation may not be possible due to configured limits in either the Client or the Server stack. The default maximum size for an array of bytes is 1 megabyte. It is recommended that Clients use the IndexRange in the OPC UA Read Service (see OPC 10000-4) to read these Variables in chunks, for example, one-megabyte chunks. It is up to the Client whether it starts without an index and repeats with an IndexRange only after an error or whether it always uses an IndexRange.
The components of the ISupportInfoType have additional references as defined in Table 24.
Table 24 – ISupportInfoType Additional Subcomponents
|Source Path||References||Node Class||BrowseName||Data Type||TypeDefinition||Others|
Pictures can be exposed as Variables organized in the DeviceTypeImage folder. There may be multiple images of different resolutions. Each image is a separate Variable.
All images are transferred as a ByteString. The DataType of the Variable specifies the image format. OPC UA defines BMP, GIF, JPG and PNG (see OPC 10000-3).
Documents are exposed as Variables organized in the Documentation folder. In most cases they will represent a product manual, which can exist as a set of individual documents.
All documents are transferred as a ByteString. The BrowseName of each Variable will consist of the filename including the extension that can be used to identify the document type. Typical extensions are “.pdf” or “.txt”.
Protocol support files are exposed as Variables organized in the ProtocolSupport folder. They may represent various types of information as defined by a protocol. Examples are a GSD or a CFF file.
All protocol support files are transferred as a ByteString. The BrowseName of each Variable shall consist of the complete filename including the extension that can be used to identify the type of information.
Images that are used within UIElements are exposed as separate Variables rather than embedding them in the element. All image Variables will be aggregated by the ImageSet folder. The UIElement shall specify an image by its name that is also the BrowseName of the image Variable. Clients can cache images so they don’t have to be transferred more than once.
The DataType of the Variable specifies the image format. OPC UA defines BMP, GIF, JPG and PNG (see OPC 10000-3).