OPC (Object linking and embedding for Process Control)

OPC (Object linking and embedding for Process Control)

OPC (Object Linking & Embedding for Process Control) is the world’s most popular standards-based data-connectivity method.
OPC is the software interface standard that allows windows programs to communicate with the industrial hardware devices.
The OPC server is the software program that converts the hardware communication protocol used by PLC into OPC protocol.
The OPC is an industry standard set up by OPC foundation specifying the software interface to a server that collects data produced by field devices and PLC
OPC resolves this by making it unnecessary for the Data Sink to know anything about how the Data Source communicates or organizes its data.
OPC eliminates the need for custom drivers between each new application and Data Source.
Using OPC greatly simplifies integration because once an OPC Connector for a particular Data Source is configured, all OPC enabled applications can start sharing data with that Data Source with no concern for additional custom drivers.

Types of Data does OPC Support

The most common types of Automation data transferred between devices, controllers, and applications break down into three broad categories
  • Real-time data
  • Historical data
  • Alarm & Event data

OPC Communication works (Conceptual)


OPC can be represented as an “abstraction” layer that sits between the Data Source and the Data Sink, allowing them to exchange data without knowing anything about each other.
OPC serves as an abstraction layer between Data Sources and Data Sinks -enabling intercommunication without either side having to know the other’s native protocol.

OPC Works (Functional View)


The OPC “device abstraction” is realized by using two, specialized OPC components called an OPC Client and OPC Server.
Each of which is described in a following section. What’s important to note is that just because the Data Source and Data Sink can communicate with each other via OPC does not mean their respective native protocols are no longer necessary or have been replaced by OPC.
Instead, these native protocols and/or interfaces are still present, but only communicate with one of the two OPC components. In turn, the OPC components exchange information amongst each other and the loop is closed.
Data can travel from the Application to the Device without having one talk directly to the other.

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