OPC Data Access 2 0 Technical Overview TM

OPC Data Access 2. 0 Technical Overview TM OLE for Process Control and Factory Automation Al Chisholm - OPC Technical Chairman 10/98

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

Why is OPC Data Access needed? Display Application Software Driver Trend Application Software Driver Report Application Software Driver

How does OPC Solve the Problem? Display Application Trend Application Report Application OPC OPC Software Driver OPC Software Driver

Where does OPC Data Access Fit? 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 Data Monitor Sub. System OPC Device Specific I/O Control Copyright 1998 Intellution, Inc. All Rights Reserved Low level sensors Typically use a dedicated Hardware Interface and protocol

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 Sensor Data OPC Interfaces Comm System Status Performance Copyright 1998 Intellution, Inc. All Rights Reserved OS Statistics

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

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. OPC Client OPC Server Existing SCADA, DCS, PLC or other Data Source FIC 101, FIC 102. . . 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). Copyright 1998 Intellution, Inc. All Rights Reserved

The Logical Object Model OPC/COM Interfaces OPCServer OPCGroup(s) OPCItem(s) OPCItem(s) OPCItem(s)

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

The Server Interfaces • The server is a COM object which provides: • • • IOPCServer IOPCBrowse. Server. Address. Space (optional) IOPCCommon (2. 0) IOPCItem. Properties(2. 0) IConnection. Point. Container(2. 0) OPCServer Copyright 1998 Intellution, Inc. All Rights Reserved

The Group Interfaces • The Group is a COM object which provides: • • • IOPCGroup. State. Mgt IOPCAsync. IO 2 (2. 0 - replaces IOPCAsync. IO) IOPCItem. Mgt IOPCSync. IO IConnection. Point. Container (2. 0 replaces IData. Object) OPCGroup Copyright 1998 Intellution, Inc. All Rights Reserved

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