OPC

ISO/OSI Model

Implemented Protocol Stacks

Applicable Products

References

The abbreviation OPC (OLE for Process Control) refers to an interface which is defined and expanded by the OPC Foundation. OPC is widely used in process automation, in particular for coupling process data to HMI systems.

OPC is based on a client-server structure. A client (master) can access one or several servers (slaves). Several clients can simultaneously access one server. One server provides the data and the client receives the data from the server. Although the client can also transmit data to the server, the main direction of data flow is from the server to the client.

OPC comprises a number of interfaces which serve various purposes. The most important are:

• DA (Data Access)
  this is probably the most widely used interface defining interfaces and methods for accessing process data
• AE (Alarm and Event)
  is an add-on to the DA interface and enables the transmission of events and alarms
• HD (Historical Data)
  is an add-on to the DA interface and enables the transmission of historical data 
• DA XML
  This interface is a fairly recent addition based on the DA interface. Data encoding is however based on XML (eXtended Markup Language).

Unlike other protocols which have mainly been developed for the transmission of process data, the OPC Foundation allows users to verify the compliance of the server implementation with the standard. This is done with the Compliance Test Tool (CTT), a software package which is made available to members free of charge. If the server passes the compliance test, a document is generated as compatibility proof and functional reference. The CCT enables the user to virtually eliminate incompatibilities between implementations from different manufacturers and ensure smooth integration.

In addition, workshops are organized on a regular basis, where different manufacturers can benchmark their systems against each other. 

Applicable Products

	ipConvOPC	Softwarepackage for conversion between OPC DA 2.05 Server and standard protocols Details...
	ipConv	Universal protocol converter for highest degree of flexibility Details...

References

	BLS AlpTransit - Lötschbergtunnel Details...	Switzerland	ipConv ipRoute	OPC DA 2.05 Server / IEC 60870-5-104, Slave / IEC 60870-5-101, Master / IEC 60870-5-104, Master / SNMP, Client /
	Mainova Communication Hub Details...	Germany	ipConv	OPC DAXML 1.01 Server / IEC 60870-5-104, Slave / IEC 60870-5-101, Master / Modbus, Master / SEAB 1F, Master /
	RWE Mosel Hydro Power Stations Details...	Germany	ipConvOPC ipRoute	OPC DA 2.05 Server / IEC 60870-5-104, Master /
	Andritz Hydro GmbH, A-Vienna Details...	South Africa	ipConvOPC	IEC 60870-5-104, Master / OPC DA 2.05 Server /
	FHKW Linz Details...	Austria	ipConvOPC	OPC DA 2.05 Server / IEC 60870-5-104, Master /