OPC breaks the Internet barrier

Sept. 1, 2003
Scottsdale The OPC Foundation has announced the release of its OPC XML Data Access (XML DA) specification, as part of a move towards platform-independent

Scottsdale — The OPC Foundation has announced the release of its OPC XML Data Access (XML DA) specification, as part of a move towards platform-independent interoperability and generic support for Internet-based Web Services. The new specification provides the gateway to the Internet for OPC data and OPC information to be transferred to and from any OPC-enabled device. A ‘wrapper’ is being provided as an easy migration path for the estimated 3000+ OPC DA products in use today.

The OPC XML data access specification enables vendors to add OPC support to any device on the factory floor that is capable of supporting a Web service. This facilitates the OPC data exchange protocol for communicating data and information seamlessly and transparently between devices independent of the operating system and networking technology that the specific device employs.

OPC Foundation President Tom Burke said: “Our vision is to proactively support technology trends, to ensure members can build highly integrated and interoperable systems. Internet-based HMI is one possibility opened up by OPC XML DA. Others include web-enabled field devices and enterprise-wide management systems. The OPC XML Data Access specification is now available complete with sample code for immediate implementation.”

Prior to the OPC XML data access specification, OPC required the use of Microsoft COM/DCOM to provide data access and exchange services between multiple vendor products. However, DCOM cannot pass firewalls so communications over the Internet have previously been impossible. XML (eXtensible Markup Language) is one of the key enabling technologies worldwide for achieving global interconnectivity and it has industry-wide support as a standardized way of handling data among systems using a variety of operating systems. Since it is text-based, XML can pass through firewalls. The OPC XML DA specification defines how XML is used by OPC clients and OPC servers, allowing end-users to deploy systems with commercial off-the-shelf products for true interoperability without having the restrictions of local networks.

Definitions for supporting Web Services are also provided, enabling users to make simple application-to-application connections over the Internet. To assist migration, the OPC Foundation has developed an adaptive wrapper that provides Foundation members with an easy way to deploy Web Services on top of existing OPC Data Access 2.x COM-based servers. This means that an estimated 3000 OPC Data Access servers worldwide could be readily Web Service enabled.

OPC Foundation Marketing Director Russ Agrusa added: “In the early days, OPC was a single goal solution for transferring data between DCS systems and HMI’s or SCADA. Things have moved fast in recent months. We have launched OPC DX for horizontal movement of data between control platforms. XML DA empowers members to develop far more sophisticated OPC products, communicating data not just between themselves but globally. A ‘system’ theme is emerging as the OPC vision enters new applications spaces. Expect to see this theme enlarged and enriched in the near future.”

The OPC Foundation, dedicated to interoperability in automation, is an independent, non-profit organization that comprises leading manufacturers and solution providers in factory and process automation. The OPC Foundation's charter is to develop worldwide industry-standards for data transfer offering multi-vendor interoperability and seamless connectivity of measurement and automation devices, systems and networks used in the manufacturing and process industries, by leveraging open computing technologies. Board members and Officers are unpaid volunteers. Development of specifications is undertaken by volunteers from 300+ members worldwide.