OPC (OLE for Process Control), OLE for process control, is an industrial standard. The international organization that manages this standard is the OPC Foundation. The OPC Foundation currently has more than 220 members.

All over the world, including all major automation control systems, instrumentation and process control system companies in the world.

Based on Microsoft's OLE (now Active X), COM (Component Object Model) and DCOM (Distributed Component Object Model) technologies.

OPC includes a standard set of interfaces, properties, and methods for use in process control and manufacturing automation systems.

Basic introduction Foreign name: OLE for Process Control Category: Software Application Platform: Windows Features: Efficiency, reliability, openness Definition and explanation, application fields, problem solving, Definition and explanation The full name of OPC is Object Linking and Embedding (OLE) for Process Control

, its emergence has established a bridge between Windows-based applications and on-site process control applications.

In the past, in order to access data information from field devices, each application software developer needed to write dedicated interface functions.

Due to the wide variety of field devices and the continuous upgrading of products, users and software developers often bring a huge workload.

Usually this cannot meet the actual needs of the work. System integrators and developers urgently need a plug-and-play device driver that is efficient, reliable, open, and interoperable.

In this case, the OPC standard came into being.

The OPC standard is based on Microsoft's OLE technology. Its formulation is completed by providing a set of standard OLE/COM interfaces. OPC technology uses OLE 2 technology. The OLE standard allows multiple computers to exchange documents,

Graphics and other objects.

COM is the abbreviation of Component Object Model and is the basis of all OLE mechanisms.

COM is a standard developed to implement objects that are independent of programming languages. The standard defines objects under Windows as independent units that can be accessed without program restrictions.

This standard enables two applications to communicate through object-based interfaces without knowing how the other party was created.

For example, the user can use the C++ language to create a Windows object, which supports an interface through which the user can access various functions provided by the object. The user can use Visual Basic, C, Pascal, Smalltalk or other languages ??to write object access programs.

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Under the Windows NT4.0 operating system, the COM specification has been extended to access other objects outside the local machine. The objects used by an application can be distributed on the network. This extension of COM is called DCOM (Distributed COM).

Through DCOM technology and OPC standards, it is possible to create an open, interoperable control system software.

OPC adopts the client/server model, placing the task of developing access interfaces on hardware manufacturers or third-party manufacturers, and providing them to users in the form of OPC servers, which solves the contradiction between software and hardware manufacturers and completes system integration.

, improving the openness and interoperability of the system.

OPC servers usually support two types of access interfaces, which provide access mechanisms for different programming language environments.

These two interfaces are: Automation interface; Custom interface.

Automation interfaces are usually standard interfaces defined based on scripting programming languages. Customer applications for OPC servers can be developed using programming languages ??such as Visual Basic, Delphi, and PowerBuilder.

The custom interface is a standard interface specially developed for high-level programming languages ??such as C++.

OPC has now become the default solution for system interconnection in the industrial world, bringing convenience to industrial monitoring programming. Users do not have to worry about communication protocols.

Any provider of automation software solutions that cannot fully support OPC will be eliminated by history.

1. In the field of control, systems are often composed of dispersed subsystems; and each subsystem often uses equipment and solutions from different manufacturers.

Users need to integrate these subsystems and build a unified real-time monitoring system.

2. Such a real-time monitoring system needs to solve the problem of data sharing among dispersed subsystems, and each subsystem needs to coordinate corresponding control instructions in a unified manner.

3. Consider that real-time monitoring systems often need to be upgraded and adjusted.

4. Each subsystem needs to have a unified open interface.

5. The OPC (OLE for Process Control) specification is the product of this thinking.