The following tables list the members exposed by DAItemValue.
Public Constructors
| Name | Description | |
|---|---|---|
 | DAItemValue Constructor |
Public Fields
| Name | Description | |
|---|---|---|
 | ClientHandle | May be used by the client to identify the item in asynchronous read replies. (Inherited from OPCDA.NET.ItemIdentification) |
| Error | HRESULT error code. (Inherited from OPCDA.NET.ItemValue) |
| ItemID | The unique identifier for this item. This element is used in the OpcServer.Read and OpcServer.Write methods to identify the item to be accessed. Some methods use the ServerHandle and ignore this element. (Inherited from OPCDA.NET.ItemIdentification) |
| MaxAge | “staleness” for the item, requested in milliseconds. The server will calculate the number of milliseconds between “now” and the item timestamp. If the item that has not been updated within the last MaxAge milliseconds, the value must be obtained from the underlying device. Or if the item is not available from the cache, it will also need to be obtained from the underlying device. A max age of 0 is equivalent to OPC_DS_DEVICE and a max age of 0xFFFFFFFF is equivalent to OPC_DS_CACHE. Without existence of a cache the server will always read from device. In this case MaxAge is not relevant. Some servers maintain a global cache for all clients. If the needed item is in this global cache, it is expected that the server makes use of it to check the MaxAge value. Servers should not automatically create or change the caching of an item based on a Read call with MaxAge. Note: Since this is a int of milliseconds, the largest MaxAge value would be approximately 24 days. (Inherited from OPCDA.NET.ItemValue) |
| Quality | Item quality status. (Inherited from OPCDA.NET.ItemValue) |
| QualitySpecified | True if the quality is defined. Some servers do not allow the item quality to be written and require this flag to be FALSE. (Inherited from OPCDA.NET.ItemValue) |
| ServerHandle | Unique handle for this item, as returned from OpcGroup.AddItems. Some methods use the ItemID and ignore this element. (Inherited from OPCDA.NET.ItemIdentification) |
| Timestamp | Item time stamp in UTC. (Inherited from OPCDA.NET.ItemValue) |
| TimestampSpecified | True if the Timestamp is defined. Some servers do not allow the item Timestamp to be written and require this flag to be FALSE. (Inherited from OPCDA.NET.ItemValue) |
| Value | Item value. (Inherited from OPCDA.NET.ItemValue) |
Public Properties
| Name | Description | |
|---|---|---|
 | Alias | Internal name that can be defined if it's necessary to reference the item in the code. |
| ClientHandle | |
| Error | |
| ItemID | |
| MaxAge | |
| Quality | |
| ServerHandle | |
| Timestamp | |
| Value |
