Based on Microsoft’s OLE (now ActiveX),COM (component object model) and DCOM (distributed component object model) technologies, OPC consists of a standard set of interfaces, properties, and methods for use in process-control and manufacturing-automation applications.The
ActiveX/COM technologies define how individual software components can interact and share data. Backed by Microsoft’s NT technology, OPC provides a common interface for communicating with diverse process-control devices, regardless of the controlling software or devices in the process. The goal of the standard is Plug-and-Play, a concept developed by Microsoft and a number of other companies a few years ago. By using a standard way of configuring computer hardware (and software interfaces) automatically, a device will easily connect to another and immediately work without the need for lengthy installation procedures or complex configuration. Instead of having to learn how to use 100 or more custom toolkits, users will only have to learn one set of tools, because all OPC drivers will work the same way. OPC’s purpose is to compel the automation industry suppliers to push all device drivers toward a standard form. Essentially, OPC defines a common interface that permits interface development work to be performed once and then easily reused.
The OPC standard requires hardware suppliers to provide front-line data collection and distribution. They are the most familiar with how to access the device’s internal data efficiently.These devices then
become OPC servers, providing data to OPC client applications consistently.Application developers can then write code in any language deemed appropriate.
OPC – History
OPC (OLE for Process Control) is an industry standard created with the collaboration of a number a leading worldwide automation and hardware software suppliers working in cooperation with Microsoft.The
organization that manages this standard is the OPC Foundation.The Foundation has over 150 members from around the world, including nearly all of the world’s major providers of control systems,
instrumentation, and process control systems.The OPC Foundation’s forerunner — a task force composed of Fisher-Rosemount, Rockwell Software, Opto 22, Intellution, and Intuitive Technology — was able to develop a basic,workable, OPC specification after only a single year’s work. A simplified, stage-one solution was released in August 1996.
The objective of the OPC Foundation is to develop an open, flexible, plug-and-play standard that allows end users to enjoy a greater choice of solutions, as well as sharply reducing development and maintenance costs for hardware and software suppliers. The OPC Foundation has been able to work more quickly than many other standards groups because OPC Foundation is simply building on an existing Microsoft standard. Other groups which have had to
define the standards “from the ground up” have had a more difficult time reaching consensus as a result of the scope of their work.
Microsoft is a member of the OPC Foundation and has given strong backing to the organization. However, Microsoft has been careful to remain in the background and let the member companies with direct industry experience guide the organization’s work.
One of the most valuable aspects of Microsoft’s participation is the fact that it hosts an annual OPC Foundation meeting in Redmond,Washington (Microsoft Headquarters) to provide Foundation Members with a preview of coming developments in OLE/COM and other Microsoft technologies. Many Foundation Members are small companies and would not receive that kind of briefing from Microsoft if they were not Foundation Members.
End-Users are encouraged to join OPC Foundation, and several manufacturers actively participate in the specification and technical review process. Both End – Users and Automation Suppliers benefit from having a standard. For every automation system installed today,
there is a significant amount of time and money spent on integration. OPC ensures that automation systems can share information and interoperate with other automation and business systems across their plant or factory.