OPC Classic Overview

GENESIS implements the OPC (Open Platform Communications) standard, often known as OPC Classic, which was first introduced in 1996. This standard enables interoperability among industrial automation systems and devices. OPC Classic facilitates the exchange of real-time data, historical data, and alarms and events across systems from different vendors. Built on Microsoft COM/DCOM (Component Object Model/Distributed Component Object Model) technology, OPC Classic is widely used across various industrial sectors, including manufacturing, building automation, oil and gas, renewable energy, and utilities.

OPC Classic communication overview

The table shows the main features of OPC Classic communication.

Feature

Description

Real-time Data Exchange

Enables transfer of live process data between devices and systems.

Historical Data Access

Provides access to historical data for analysis and reporting.

Alarms and Events Management

Supports the transmission of alarms and events to monitor critical system changes.

Vendor-Neutral Communication

Facilitates seamless interoperability between hardware and software from different manufacturers.

Scalability and Flexibility

Easily integrates into both small-scale and enterprise-level systems.

OPC Classic Components

OPC Classic is divided into three core specifications, each designed for specific use cases.

  • OPC Data Access (OPC DA):

    • Handles real-time data transfer.
    • Provides read, write, and subscription functionality for live process data.

  • OPC Historical Data Access (OPC HDA):

    • Focuses on accessing and analyzing historical data.
    • Useful for long-term trend analysis and reporting.

  • OPC Alarms and Events (OPC A&E):

    • Manages the transmission and handling of alarms and events.
    • Allows users to track and respond to critical system changes in real time.

OPC Classic Limitations

While OPC Classic offers numerous benefits, it has a few limitations.

  • Dependency on COM/DCOM: Relies on Microsoft COM/DCOM, which may have security and performance challenges, especially in distributed networks.
  • Complex Configuration: DCOM configuration can be difficult and prone to errors.
  • Limited Platform Support: Restricted to Windows operating systems.

Transition to OPC UA

As technology evolved, the need for a new OPC architecture emerged. In 2008, the OPC Foundation released OPC Unified Architecture (OPC UA), a platform-independent, service-oriented architecture that serves as the successor to OPC Classic. OPC UA offers several advantages:

  • Cross-Platform Support: Operates on multiple platforms, including Linux and macOS.
  • Improved Security: Features robust security mechanisms such as encryption and user authentication.
  • Scalability: Suits modern industrial systems and IoT environments better than OPC Classic.

For more information about OPC Classic specifications, visit the official OPC Foundation website.