The following tables list the members exposed by SubscribeRequestItem.
Public Constructors
| Name | Description | |
|---|---|---|
 | SubscribeRequestItem 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. |
| Deadband | Specifies the percentage of full engineering unit range of an item??s value that must change prior to being returned in a SubscriptionPolledRefresh response. The deadband value shall be in the range 0-100 percent and only applies to analog (integer or float) types. The deadband will also apply to array types. The entire array is returned if any array element exceeds the deadband threshold. Server default is 0. See the OPC DA Custom Specification for further detail. |
| DeadbandSpecified | If FALSE then the Deadband value is not defined or ignored. |
| EnableBuffering | If True, the client is requesting that the server use the RequestedSamplingRate to check for value changes and save all changes in a buffer for return to the client at the next SubscriptionPolledRefresh request. See the section on Data Management Optimization in this document and OPC DA Custom Specification for further detail. |
| EnableBufferingSpecified | If FALSE then the EnableBuffering value is not defined or ignored. |
| 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. |
| 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. |
| RequestedSamplingRate | The client specifies the rate in milliseconds at which the server should check for value changes. If no item-specific sampling rate is specified, sampling will be based on the rate of the item list. See the section on Data Management Optimization in this document and OPC DA Custom Specification for further detail. |
| RequestedSamplingRateSpecified | If FALSE then the RequestedSamplingRate value is not defined or ignored. |