Opc data Access Automation Specification

Revision 2.0 Highlights 

This revision replaces the Data Access Automation Interface previously documented in the OPC Data Access 1.0A 

Specification. Basically the automation interface architecture was redesigned to address ease of use by Visual Basic 

Programmers, and to take advantage of the technology improvements, inclusive of automation events and object support for 

the WithEvents keyword. 

Revision 2.01 January 6, 1999 Highlights 

As noted elsewhere a draft version of the Specification was inadvertently circulated as Version 2.0. The 'correct' version 2.0 

has been relabeled as 2.01 (this document), redated and republished. The basic changes between the draft dated October 14, 

1998 and this document include: 

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Removal of AsyncRefreshComplete (event for refresh follows custom interface architecture, with data returned in 

DataChange Event); 

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Change to AsyncCancelComplete to return the Transaction ID associated with the method being canceled;  

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Changing reference to NumItems to Count;  

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Correction to OPC error numbering; 

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Adding NON-EXCLUSIVE LICENSE AGREEMENT Section; 

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Minor formatting changes.