Copyright 1998 Intellution, Inc. All Rights Reserved TM OLE for Process Control and Factory...

Copyright 1998 Intellution, Inc. All Rights Reserved

TM

OLE for Process Control and Factory

AutomationAl Chisholm - OPC Technical Chairman10/98

OPC Data Access 2.0 Technical OPC Data Access 2.0 Technical OverviewOverview


TopicsTopics

• A review of the Data Access Problem• Design Features• Assumptions about the Applications• The Objects• The functionality they provide


Why is OPC Data Access needed?Why is OPC Data Access needed?

SoftwareDriver

SoftwareDriver

SoftwareDriver

SoftwareDriver

DisplayApplication

TrendApplication

ReportApplication


How does OPC Solve the Problem?How does OPC Solve the Problem?

SoftwareDriver

SoftwareDriver

SoftwareDriver

SoftwareDriver

OPC OPC OPC OPC

DisplayApplication

TrendApplication

ReportApplication

OPC OPC OPC


Where does OPC Data Access Fit?Where does OPC Data Access Fit?

Low level sensorsTypically use a dedicated

Hardware Interface and protocolDevice Specific I/O Control

Data MonitorSubSystem

OPC

OPC (via DCOM)can also be used between subsystemsand Management Consoles

OPC is generally usedbetween Monitoring

applications and I/O specificsoftware drivers


What data does OPC provide?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

CommStatus

System Performance

OS Statistics


Features of OPC Data AccessFeatures 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 ArchitectureAssumptions 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

SourceFIC101, FIC102...

OPC Server

OPC Client


Assumptions about the ApplicationsAssumptions 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).


The Logical Object ModelThe Logical Object Model

OPCServer

OPCGroup

OPC/COMInterfaces

OPCGroupOPCGroup(s)

OPCItem(s)OPCItem(s)OPCItem(s)OPCItem(s)OPCItem(s)OPCItem(s)

OPCItem(s)OPCItem(s)OPCItem(s)


Typical Server DesignTypical Server Design

OPC/COM Interfaces

OPC Group & Item Management

Item Data Optimization and Monitoring

Device Specific Protocol Logic

Hardware Connection Management


The Server InterfacesThe Server Interfaces

• The server is a COM object which provides:

• IOPCServer• IOPCBrowseServerAddressSpace (optional)• IOPCCommon (2.0)• IOPCItemProperties(2.0)• IConnectionPointContainer(2.0)

OPCServer


The Group InterfacesThe Group Interfaces

• The Group is a COM object which provides:

• IOPCGroupStateMgt• IOPCAsyncIO2 (2.0 - replaces IOPCAsyncIO)• IOPCItemMgt• IOPCSyncIO • IConnectionPointContainer (2.0 replaces

IDataObject)

OPCGroup


The Client Side IntefacesThe Client Side Intefaces

• The Client provides 2 COM interfaces that the server can call

• IOPCShutdown• IOPCDataCallback Server Object

Group Object(s)Client

IOPCDataChange

IOPCShutdown


Performance and FlexibilityPerformance 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.


SummarySummary

• 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 TM OLE for Process Control and Factory...

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Transcript of Copyright 1998 Intellution, Inc. All Rights Reserved TM OLE for Process Control and Factory...