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Read Item Attributes

Each item that you find on a server might have a given set of item attributes associated with it. These attributes provide information about the item stored on the server. The OPC Foundation defines a set of common item attributes, while specific servers can define server-specific attributes. However, support for item attributes is optional for any server.

You can find the attributes supported by your server by interrogating the ItemAttributes property of a connected HDA client object:

OPC HDA Item Attributes:
         Name           ID        Description   
    --------------  ----------  ----------------
    DATA_TYPE           1       Data type
    DESCRIPTION         2       Item Description
    NORMAL_MAXIMUM      11      High EU
    NORMAL_MINIMUM      12      Low EU
    ITEMID              13      Item ID
    TRIANGLE        4294967291  Triangle Wave
    SQUARE          4294967292  Square Wave
    SAWTOOTH        4294967293  Saw-toothed Wave
    RANDOM          4294967294  Random
    BUCKET          4294967295  Bucket Brigade

You use the readItemAttributes function to retrieve the item attributes for a particular item.

For a list of OPC defined item attributes for the OPC HDA specification, see OPC HDA Item Attributes.