AsyncRefresh method
Description | Generates an event to read all active items in the group (whether they have changed or not). Inactive items are not included in the callback. The results are returned via the DataChange event associated with the OPCGroup object. |
Syntax | AsyncRefresh (Source As Integer, TransactionID As Long,ByRef CancelID As Long)Source — The 'data source'; OPC_DS_CACHE or OPC_DS_DEVICETransactionID — The client specified transaction ID. This is included in the DataChange Event.CancelID — A Server generated CancelID. This is provided to enable the client to cancel the transaction. |
Remarks | The AsyncRefresh requires the OPCGroup object to have been dimensioned to handle events (Dim WithEvents MyOPCGroup As OPCGroup) in order for the results of the refresh operation to be returned to the client. The DataChange event associated with the OPCGroup object will be called by the Data Access Server with the results of the refresh operation. |
Example | Dim lTransID As Long Dim lCancelID As Long '/* Refresh all active items in the group MyOPCGroup.AsyncRefresh OPC_DS_DEVICE, lTransID, lCancelID |
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