1. Copyright 1998 Intellution, Inc. All Rights Reserved TM OLE for Process Control and Factory Automation Al Chisholm - OPC Technical Chairman 10/98 OPC Data Access 2.0 Technical Overview

2. Copyright 1998 Intellution, Inc. All Rights Reserved Topics A review of the Data Access Problem Design Features Assumptions about the Applications The Objects The functionality they provide

3. Copyright 1998 Intellution, Inc. All Rights Reserved Why is OPC Data Access needed? Software Driver Software Driver Software Driver Software Driver Display Application Trend Application Report Application

4. Copyright 1998 Intellution, Inc. All Rights Reserved How does OPC Solve the Problem? Software Driver Software Driver Software Driver Software Driver OPC Display Application Trend Application Report Application OPC

5. Copyright 1998 Intellution, Inc. All Rights Reserved Where does OPC Data Access Fit? Low level sensors Typically use a dedicated Hardware Interface and protocol Device Specific I/O Control Data Monitor SubSystem OPC OPC (via DCOM)can also be used between subsystems and Management Consoles OPC is generally used between Monitoring applications and I/O specific software drivers

6. Copyright 1998 Intellution, Inc. All Rights Reserved What data does OPC provide? Real time sensor data - temp, pressure, flow Control parameters - open, close, run, stop Status information – Status of the hardware connection – Status of the local software and subsystem OPC can expose any data available OPC Interfaces Sensor Data Comm Status System Performance OS Statistics

7. Copyright 1998 Intellution, Inc. All Rights Reserved Features of OPC Data Access Based on COM - to leverage Microsoft ‘Plumbing’ Flexible - to support many applications Efficient & Scalable - to support large applications Hi performance - well behaved on a Network Easy to understand Widely accepted

8. Copyright 1998 Intellution, Inc. All Rights Reserved Assumptions About the Architecture Each OPC Server such as Data Access is a Separate Object The Data Access Server provides a window into Existing Data; it is not a configuration system. Data is accessed by Name (a string) which will generally be vendor or hardware specific. Data for lists of items can be read explicitly (polled) or subscriptions can be created. Existing SCADA, DCS, PLC or other Data Source FIC101, FIC102... OPC Server OPC Client

9. Copyright 1998 Intellution, Inc. All Rights Reserved Assumptions about the Applications Applications are interested in a subset of the Data Items (Tags) available within the underlying Control sub-system. Applications are interested in many different subsets of Data Items at different times and may have variable requirements for response and resolution. Applications want to be independent of the data structures (or objects) used by the sub-systems. (I.e. they want symbolic access to the data).

10. Copyright 1998 Intellution, Inc. All Rights Reserved The Logical Object Model OPCServer OPCGroup OPC/COM Interfaces OPCGroup OPCGroup(s) OPCItem(s)

11. Copyright 1998 Intellution, Inc. All Rights Reserved Typical Server Design OPC/COM Interfaces OPC Group & Item Management Item Data Optimization and Monitoring Device Specific Protocol Logic Hardware Connection Management

12. Copyright 1998 Intellution, Inc. All Rights Reserved The Server Interfaces The server is a COM object which provides: IOPCServer IOPCBrowseServerAddressSpace (optional) IOPCCommon (2.0) IOPCItemProperties(2.0) IConnectionPointContainer(2.0) OPCServer

13. Copyright 1998 Intellution, Inc. All Rights Reserved The Group Interfaces The Group is a COM object which provides: IOPCGroupStateMgt IOPCAsyncIO2 (2.0 - replaces IOPCAsyncIO) IOPCItemMgt IOPCSyncIO IConnectionPointContainer (2.0 replaces IDataObject) OPCGroup

14. Copyright 1998 Intellution, Inc. All Rights Reserved The Client Side Intefaces The Client provides 2 COM interfaces that the server can call IOPCShutdown IOPCDataCallback Server Object Group Object(s) Client IOPCDataChange IOPCShutdown

15. Copyright 1998 Intellution, Inc. All Rights Reserved Performance and Flexibility OPC Data Access is complete, powerful and flexible because it is a combination of the best ideas of many of the best companies in our business. OPC Data Access is Fast because it was designed from the start with networking in mind.

16. Copyright 1998 Intellution, Inc. All Rights Reserved Summary The OPC Data Access 2.0 Interfaces Allow applications to easily access subsystem data Support polled or exception based access Are optimized for use over a network Are designed to be vendor neutral Are exceptionally flexible and efficient www.opcfoundation.org