OPC Classic Server

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Introduction

The OPC Classic Specification is a software interface standard that allows programs to communicate with industrial hardware devices. You can connect OPC Classic aware client applications directly to Fernhill SCADA without needing any custom interface software:

Diagram showing Fernhill SCADA relationship with OPC clients

Fernhill SCADA supports these OPC Classic interfaces:

OPC Use Cases

Using the OPC Classic Server and a suitable client application you can:

Supported Interfaces

The OPC Classic Server in Fernhill SCADA supports these interfaces:

OPC Server
IOPCCommon
IOPCSecurityNT
IOPCServer
IOPCItemProperties
IOPCItemIO
IOPCBrowseServerAddressSpace
IOPCBrowse
IOPCEventServer
IOPCHDA_Server
IOPCHDA_SyncRead
IConnectionPointContainer

OPC Data Access groups support these interfaces:

OPC Data Access Group
IOPCItemMgt
IOPCGroupStateMgt
IOPCGroupStateMgt2
IOPCSyncIO
IOPCSyncIO2
IOPCAsyncIO
IOPCAsyncIO2
IOPCAsyncIO3
IOPCItemDeadbandMgt
IDataObject
IConnectionPointContainer

OPC Alarms and Events subscriptions support these interfaces:

OPC Event Subscription
IOPCEventSubscriptionMgt
IConnectionPointContainer

The specification of these interfaces is defined by the OPC foundation.

OPC Foundation

The OPC foundation is a non-profit organization that defines and promotes OPC standards for data exchange in Industrial Automation and other related domains.

DCOM

The OPC Classic Server in Fernhill SCADA is an in-processCOM server, which avoids any need to set up DCOM.

When the OPC Client application is not on the same computer as Fernhill SCADA, install the OPC Classic Server on the client computer. The Fernhill SCADA Setup program provides the install option Data Access Interfaces for this. In this scenario, the OPC Client application loads the in-process OPC Classic Server, which in turn communicates with Fernhill SCADA using TCP/IP.

The OPC Classic Server in Fernhill SCADA also supports out-of-process activation using the standard Windows DLL Surrogate DLLHost.exe.

Further Information

Diagnosing Connection Problems

If you are having problems connecting to a Fernhill SCADA Server.

OPC Classic Server Administration Tool

To learn how to connect OPC Clients to different computers running Fernhill SCADA.

Using C/C++ to access an OPC Classic Server

For a guide to writing C/C++ code to access an OPC Classic Server.

opcfoundation.org

For information about the OPC standards.

Glossary

For the meaning of terms used in Fernhill SCADA.