The following tables list the members exposed by ReadRequestItem.
Public Constructors
| Name | Description | |
|---|---|---|
 | ReadRequestItem Constructor |
Public Properties
| Name | Description | |
|---|---|---|
 | ClientItemHandle | A string that can be passed by the client and be returned along with the data. If the Client includes the ClientItemHandle attribute, then Server must return it to the Client. |
| ItemName | Identifier of the Data. It is free format (as in the OPC COM server). Required attribute. |
| ItemPath | A portion of the namespace pointing to the data. The ItemPath is server specific and the client should not make any implications about its content, structure, or consistency across servers. ItemPath may or may not imply node, or server. If an XML-DA server was front ending a DA based server, then an example could be: \\NODE\OPC.DAServer.2. ItemPath is a hierarchical parameter. If ItemPath is Blank or missing at all levels of the hierarchy, then the ItemName is expected to be a fully qualified name. |
| MaxAge | Indicates the requested freshness of the data in number of milliseconds. The data should be no older than this value. If omitted or if the value is 0 at all levels of the hierarchy then the server should return the most accurate data available (which is analogous to a ??DEVICE? read in the COM server ?? reference the corresponding section of the OPC DA Specification to get further clarification on this concept.). |
| MaxAgeSpecified | If FALSE then the MaxAge value is not defined or ignored. |
| ReqType | Specifies the client??s requested type for the Item??s value to be returned by the server for a Read request. A Blank or missing or ??anyType? ReqType will indicate to the server to use the canonical data type. If the client specifies a type, and the server is unable to respond to the request, then an error will be returned in the Response. See ??Data Types for Item Values? specification section. Also see the corresponding section in the OPC DA Custom Specification to see which conversions are supported. |