An OPC Server is a software application that acts as an API (Application Programming Interface) or protocol converter. An OPC Server will connect to a device such as a PLC, DCS, RTU, or a data source such as a database or User interface, and translate the data into a standard-based OPC format. OPC compliant applications such as an HMI (Human Machine Interface), historian, spreadsheet, trending application, etc. can connect to the OPC Server and use it to read and write device data. An OPC Server is analogous to the role a printer driver plays to enable a computer to communicate with an ink jet printer. An OPC Server is based on a Server/Client architecture.
Based on Microsoft Windows technology, OPC now stands for Open Process Control. Previously it stood for OLE Process Control but today the OLE technology has been replaced by Active X.
OPC (originally OLE for process control) is an industry standard created with the collaboration of a number of leading worldwide automation hardware and software suppliers, working in cooperation with Microsoft. The standard defines methods for exchanging realtime automation data between PC-based clients using Microsoft operating systems. The organization that manages this standard is the OPC Foundation.
"The OPC Specification is a non-proprietary technical specification that defines a set of standard interfaces based upon Microsoft s OLE/COM/DCOM platform and .NET technology. The application of the OPC standard interface makes possible interoperability between automation/control applications, field systems/devices and business/office applications."
"Traditionally, each software or application developer was required to write a custom interface, or server/driver, to exchange data with hardware field devices. OPC eliminates this requirement by defining a common, high performance interface that permits this work to be done once, and then easily reused by HMI, SCADA, Control and custom applications."
An OPC Server is often referred to as an OPC Driver. The two terms are synonymous.