OPC (OLE for Process Control) is a standard communication protocol widely used in the industrial automation industry. It provides a means of interoperability and data exchange between different software applications and hardware devices used in industrial control systems.
OPC was originally developed by the OPC Foundation, which stands for Object Linking and Embedding (OLE) for Process Control. The protocol is based on Microsoft’s OLE and COM (Component Object Model) technologies, which allow software components to communicate and interact with each other.
OPC is designed to facilitate the exchange of real-time and historical data, as well as alarms and events, between various devices and applications in an industrial environment. It enables seamless integration and communication between different systems, such as supervisory control and data acquisition (SCADA) systems, distributed control systems (DCS), programmable logic controllers (PLC), and other automation devices.
There are different versions of OPC, each with its own specifications and capabilities. The most commonly used versions are OPC Classic and OPC Unified Architecture (OPC UA).
OPC Classic, also known as OPC DA (Data Access), is focused on real-time data exchange. It allows applications to read and write data from and to industrial devices, providing access to process variables and control parameters.
OPC UA, on the other hand, is a more advanced and modern version of OPC. It offers enhanced security, improved scalability, and expanded functionality compared to OPC Classic. OPC UA supports not only real-time data exchange but also extensive information modeling, historical data access, alarms and events, and more. It is designed to be platform-independent and capable of operating over various network protocols, including Ethernet, TCP/IP, and web services.
OPC has become a widely adopted standard in the industrial automation industry due to its ability to enable interoperability and facilitate the integration of diverse systems and devices. By using OPC, different software applications and hardware devices from multiple vendors can communicate seamlessly, allowing for efficient data sharing, monitoring, control, and analysis in industrial control systems.
What are the examples of industrial control systems that use OPC?
There are numerous industrial control systems that utilize OPC for communication and data exchange. Here are some examples:
- SCADA Systems: OPC is often used in Supervisory Control and Data Acquisition systems, which monitor and control industrial processes. OPC allows SCADA systems to communicate with various devices in real-time, gather data, and provide control signals.
- Distributed Control Systems (DCS): DCS relies on OPC for seamless integration and communication between different control modules, controllers, and field devices. OPC enables centralized control and data exchange in large-scale industrial processes.
- Programmable Logic Controllers (PLC): OPC is commonly used to connect PLCs with higher-level systems such as SCADA or MES (Manufacturing Execution Systems). It allows for data sharing, remote monitoring, and control of PLC-based automation systems.
- Human-Machine Interfaces (HMIs): OPC is utilized in HMIs to establish communication between the operator interface and the underlying control system. It enables real-time data visualization, alarm monitoring, and control actions.
- Historians: OPC is often employed in historian systems, which collect and store historical process data for analysis and reporting purposes. OPC enables the retrieval and storage of data from various sources, facilitating long-term data archiving.
- Asset Management Systems: OPC is used in asset management systems to gather real-time data from field devices, perform diagnostics, and monitor equipment health. It enables proactive maintenance and optimization of industrial assets.
- Energy Management Systems: OPC is utilized in energy management systems to acquire data from energy meters, sensors, and control devices. It allows for real-time monitoring, analysis, and optimization of energy consumption in industrial facilities.