PACiS GTW GTW/EN T/C40, Техническое руководство

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GTW/EN CT/C40 Communication
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7.2.2 OPCGroup object
The OPC Group object is delivered by the server to manage a collection of items. The set of
interfaces provided by this object includes:
- IOPCItemMgt
- IOPCGroupStateMgt
- IOPCSyncIO
- IOPCAsyncIO2
- IConnectionPointContainer
IOPCItemMgt
This interface allows the client to add, remove and control the behaviour of items in the
group.
IOPCGroupStateMgt
This interface allows the client to manage the overall state of the group (mainly update rate
control and active state management).
IOPCSyncIO
This interface allows the client to perform synchronous read and write operations to the
server. These operations will run to completion.
IOPCAsyncIO2
This interface allows the client to perform asynchronous read and write operations to the
server. Theses operations will be queued and the methods of the interface will return
immediately so that the client can go on running. When the operations are completed, a
callback will be made to the IOPDataCallback in the client.
IConnectionPointContainer
This interface allows the client to retrieve connection points so it can setup callback
mechanism for asynchronous communication from the server. As defined by the OPC
specification the callback mechanism available from the OPCGroup is the
IOPCDataCallback interface.
The OPCGroup is provided by the CCOMOPCGroup object. The following diagram presents
it: