OPC Studio User's Guide and Reference
IEasyDAClientExtension Class Methods


OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess Namespace : IEasyDAClientExtension Class

For a list of all members of this type, see IEasyDAClientExtension members.

Public Methods
 NameDescription
Public Methodstatic (Shared in Visual Basic)

Browses the possible access paths of a specified OPC item.

Browse for access paths. Specify machine name, server class, and item ID.

 
Public Methodstatic (Shared in Visual Basic)Overloaded. Browses the specified branch (or root) in OPC server's address space, and returns information about child branches found.

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Public Methodstatic (Shared in Visual Basic)Overloaded. Browses the specified branch (or root) in OPC server's address space, and returns information about child leaves found.

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Public Methodstatic (Shared in Visual Basic)

Browses the specified branch (or root) in OPC server's address space, and returns information about child nodes (both branches and leaves) found.

Browse for child nodes. Specify machine name, server class, parent item ID, and node filter.

 
Public Methodstatic (Shared in Visual Basic)

Browses the available properties of a specified OPC item.

Browse for available item properties. Specify machine name, server class, and item ID.

 
Public Methodstatic (Shared in Visual Basic)Overloaded. 

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Public Methodstatic (Shared in Visual Basic)Overloaded. Changes parameters of a subscription to a particular OPC item.

It is more efficient to change multiple subscriptions using ChangeMultipleItemSubscriptions method.

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Public Method (Inherited from object)
Public MethodServes as the default hash function. (Inherited from object)
Public Methodstatic (Shared in Visual Basic)Overloaded. Gets values of multiple OPC properties of a specified OPC item.

This method does not throw an exception in case of OPC operation failures. Instead, the eventual exception related to each property is returned in Exception property of each returned OpcLabs.BaseLib.OperationModel.ValueResult element.

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Public Methodstatic (Shared in Visual Basic)Overloaded. Gets a value of OPC property of a specified OPC item.

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Public MethodGets the System.Type of the current instance. (Inherited from object)
Public Methodstatic (Shared in Visual Basic)Attempts to pull an OPC item change subscribed to by the SubscribeMultipleItems or SubscribeItem method.  
Public Methodstatic (Shared in Visual Basic)Overloaded. Reads a named item from an OPC server. Value, quality and timestamp are returned.

The server can be local or can be remotely accessed via DCOM. Optionally, an access path can be specified or a specific data type can be requested.

The ReadItem method only waits for the first update from the server (or until the timeout elapses); it does not wait until the quality becomes "uncertain" or "good".

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Public Methodstatic (Shared in Visual Basic)Overloaded. Reads a named item from an OPC server. Only the item value is returned (quality and timestamp are not returned).

The server can be local or can be remotely accessed via DCOM. Optionally, an access path can be specified or a specific data type can be requested.

Use this method if you are only interested in the actual value of the OPC item. Use ReadItem method if you also need the quality or timestamp. The ReadItemValue method makes it very easy to obtain the actual data value with just one function call.

The ReadItemValue method waits until the quality becomes "good", or the timeout elapses.

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Public Methodstatic (Shared in Visual Basic)Overloaded. Reads named items from an OPC server or OPC servers. Values, qualities and timestamps are returned.  
Public Methodstatic (Shared in Visual Basic)Overloaded. Reads named items from an OPC server or OPC servers. Only the item values are returned (qualities and timestamps are not returned).

The servers can be local or can be remotely accessed via DCOM. Optionally, an access path can be specified or a specific data type can be requested.

The ReadMultipleItemValues method requires that the quality is "good" for each item. The function performs all individual operations in parallel, but only returns after all individual operations are completed (or their timeouts elapse).

This method does not throw an exception in case of OPC operation failures. Instead, the eventual exception related to each item is returned in Exception property of each returned OpcLabs.EasyOpc.DataAccess.OperationModel.DAVtqResult element.

 
Public Methodstatic (Shared in Visual Basic)Overloaded. Subscribe to changes of a particular OPC item. The ItemChanged event is generated for each significant item change.

It is more efficient to subscribe to multiple items using the SubscribeMultipleItems method.

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Public Methodstatic (Shared in Visual Basic)Overloaded. Subscribe to changes of multiple OPC items.  
Public MethodReturns a string that represents the current object. (Inherited from object)
Public Methodstatic (Shared in Visual Basic)

Unsubscribe from changes of a particular OPC item.

Unsubscribe from OPC item, specifying its handle.

 
Public Methodstatic (Shared in Visual Basic)Overloaded. Writes into a named item in an OPC server. Value, quality and timestamp are written.

The server can be local or can be remotely accessed via DCOM. Optionally, an access path can be specified or a specific data type can be requested.

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Public Methodstatic (Shared in Visual Basic)Overloaded. Writes a value into a named item in an OPC server. Only the item value is written (quality and timestamp are not written).

The server can be local or can be remotely accessed via DCOM. Optionally, an access path can be specified or a specific data type can be requested.

 
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Protected Methods
 NameDescription
Protected MethodAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from object)
Protected MethodCreates a shallow copy of the current System.Object. (Inherited from object)
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See Also

Reference

IEasyDAClientExtension Class
OpcLabs.EasyOpc.DataAccess Namespace