What is OPC?

OPC is a series of standards specifications. The first standard was originally called simply the OPC Specification and now referred to as OPC DA, Data Access Specification. The classic OPC specifications are based on Microsoft’s OLE COM (component object model) and DCOM (distributed component object model) technologies, the specification defined a standard set of objects, interfaces and methods for use in process control and manufacturing automation applications to facilitate interoperability. The COM/DCOM technologies provided the framework for software products to be developed. There are now hundreds of OPC Data Access servers and clients being used to automate the transfer of data from a control system (PLC, DCS, analyzer, etc) to an industrial software application (HMI, Historian, Production system, Management system, etc).

 

In terms of the Purdue Model of Computer Integrated Manufacturing, OPC is typically used to interface between Level 2 and Level 3 or higher.  OPC is commonly used to transfers data between Area Operations (Level 2) on the control network and Plant-wide Operations and Control (Level 3) or higher to the Business/Planning (Level 4) network.

 

For more on OPC see the webcast “The ABC’s of OPC”