OPC - the standard that makes other standards interoperable

By : Jim Pinto,
San Diego, CA.
USA

Standards are intrinsically difficult to implement and adopt. In the industrial automation business, OPC is a unifying standard that allows true interoperability. It needs more end-user support and involvement.

This article was published by:

Automation.com, October 2006

The dichotomy of standards

End-users want standards because, more than anything else, they provide interoperability and reduce dependence on any specific supplier. For this very reason, suppliers only pretend to support standards, when, in reality, the ones they really promote are those that give them a distinct proprietary advantage. This dichotomy is succinctly expressed by a couple of verses from one of my fieldbus poems:

The basic cause of all the fuss
The Users want an Open bus
They push and threaten, beg and plead
"Interoperable" is what they need
The widgets made by Vendor A
With Vendor B must plug and play

The Vendors swear they all agree
But just can’t bear to make it free
An open door will throw away
Their value-core and make it gray
Proprietary will be gone
To hordes of hungry hangers-on

End-users cannot drive standards; there are few users big enough to set standards independently, and cooperation through committees merely results in analysis paralysis. Supplier involvement compounds the confusion because they simply promote their own preferences.

Suppliers cannot overtly promote standards where they have a clear edge, because that inhibits adoption by competitive suppliers. So, major suppliers entice others to adopt their technology through promoting “open standards associations”. They “donate” sufficient information for others to develop a broad range of products, but maintain their advantage through ownership of key intellectual property.

The result of this confusion is that most suppliers hedge their bets – they participate in all the standards organizations, to keep tabs on what is going on and ensure that they are not left out.

Conflicting standards have bad effects for everyone. Customers get confused and postpone purchases to see how the market settles. And suppliers limit investment in development of products that may end up being “non-standard”. So growth is inhibited and the market becomes fragmented.

For industrial networking, there are several standards (notice the dichotomy in that statement). After a lot of politicking by suppliers, the international “fieldbus” committee actually approved eight different standards, some of them directly competitive. This was evidently a compromise; one must assume that the decision was made primarily to put an end to the conflict and allow the market to decide which standards achieved the broadest adoption.

End-users are left with a severe problem

Industrial automation is served by many different suppliers, each offering products and systems purporting to support a particular “standard”. But the diversity of industrial applications means that no single company can provide the broad spectrum of products required.

A particular supplier may offer the best price/performance for parts of the system but may be inferior, or not have anything to offer, in other important sections of the same system. And worse, products from different suppliers may not interface correctly and the industrial networks on which they are based are often not interoperable.

Typically, end-users must choose from a mix of proprietary products and technologies with limited possibilities for integration of overall system communications. This is the old nemesis of “islands of automation” which the industry has been trying to overcome. But end-users continue to have multiple vendor dependencies, and their systems become a service and maintenance nightmare.

What end-users need is the freedom to choose the best products from many different suppliers, with network interfaces or “glue” that makes everything play together beyond proprietary boundaries. That “glue” is OPC.

OPC – linking proprietary products & protocols

OPC is open connectivity through the creation and maintenance of open standards specifications. The OPC Foundation is an independent, international organization that brings together leading suppliers, solution providers and end-users in factory automation and process control markets to provide interoperability between products from cooperating suppliers.

The acronym OPC originates from an earlier organization: “OLE for Process Control”. OLE was “Object Linking and Embedding” which (in the past) was Microsoft’s software mechanism for linking different product protocols. Today, OPC involvement has gone beyond just process control, to factory automation and other industrial applications, and indeed is now extending to enterprise systems.

The OPC Foundation has been able to work more quickly than many other standards groups because it utilizes cooperation between OPC members to make their products interoperable through extensions of their own existing standards. Other industry committees which have tried to define standards from the ground up have found it more difficult to reach consensus between competing vendors.

Microsoft is a member of the OPC Foundation and has given strong backing to the organization. Microsoft products have become a de-facto standard in industrial automation; the company acts as a technology advisor and provides previews of coming technology changes with involvement in testing for backward compatibility. OPC member companies with direct industrial automation experience guide the OPC organization's work and get involved in the development of OPC specifications.

The OPC 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.

OPC assures interoperability by creating and maintaining open specifications that standardize the communication of acquired process data, alarm and event records, historical data, and batch data between production devices in multi-vendor enterprise systems. Production devices include sensors, instruments, PLCs, RTUs, DCSs, HMIs, historians, trending subsystems, alarm subsystems, and the like.

The vision of OPC is to be the foundation for interoperability, to facilitate moving information horizontally (between devices on different industrial networks from different vendors) and vertically from the process plant and factory floor through the enterprise.

Collaboration between suppliers is the key to pulling multiple “open” standards into unified open platform architectures. OPC monitors technologies and trends, and collects feedback from end-users and solutions providers to help adapt and improve performance, and ensure linkages between products from different suppliers.

OPC organizes a series of road-shows, seminars and technology events. The foundation tracks emerging new markets and collaborates with major organizations and suppliers to investigate new technology. Volunteers in all OPC working groups help to drive technology forward and prepare for future challenges.

OPC Unified Architecture

Since its inception in 1996, the OPC Foundation has been very successful in standardizing access to device architectures (OPC-DA). The next generation Unified Architecture (OPC-UA) is extending OPC influence to enterprise solutions. This not only supersedes existing interfaces, but also includes significant new capabilities.

With OPC-UA, several steps have been taken to align more closely with enterprise technologies and needs. OPC-UA is based on Web services and XML, and also defines a binary encoding for speed when needed. OPC-UA relies on standard Web service security mechanisms and includes complex data structures with an object-base approach; support for messaging is expected. OPC is still in the process of documenting how OPC-UA is intended to fit within standards-based enterprise architectures.

With OPC-UA, The OPC Foundation has clearly indicated that they intend to enable enterprise interoperability, and expect to solve enterprise integration challenges. This is a very ambitious undertaking and it has been difficult to determine what elements of enterprise interoperability can actually be standardized. It is clear that OPC-UA does not provide everything needed for interoperability from the enterprise-IT perspective, but the impact is expected to be considerable.

The OPC Foundation Compliance Certification Program provides manufacturers with the ability to specify products and solutions from automation and enterprise suppliers that meet compliance criteria for reliability, security, interoperability, and maintainability, so as to be completely plug-and-play. This addresses the multi-vendor “nightmare” previously discussed, and enables end-users to reduce their system installation costs plus significant additional benefits.

The Compliance Certification Program includes automation as well as enterprise suppliers, end-users, standards bodies and universities. It consists of Compliance Test Tools (CTT), Interoperability Sessions (IOP), and Independent Test Labs. CTTs will provide for self testing and verification of OPC server interfaces, and provide debugging support.

IOP workshops are held in the U.S., Europe and Japan each year to test products with other OPC suppliers who can run tests on combinations of OPC client and server products. Independent Test Labs provide a reproducible environment for performing interoperability, functional, behavior, performance, usability, and environmental tests.

Compliance certification will provide manufacturers with the confidence that, provided both suppliers are OPC compliance certified, any supplier’s products will work right out of the box with any other supplier’s products. Specifying OPC compliance certification is the end-user’s best assurance that products purchased from different suppliers are indeed interoperable.

Who are the OPC members?

Today OPC has over 400 member companies, and membership is expected to grow to 1,000 over the next few years. Already, more than 2,500 different companies use and build about 15,000 OPC compliant products.

All major automation suppliers are members – Siemens, ABB, Rockwell, Honeywell, etc.; about 45% of OPC members are relatively small companies (<2 M$). Membership is equally spread between North America and Europe. Review the current list of OPC members, weblink below. Success is measured by level of adoption, which stems from the dedication of OPC members to design & build & deliver products that are OPC compliant and interoperable with products of other OPC members. In the future, more end-users will demand OPC compliance certification as the endorsement of interoperability.

The success of OPC comes from strong involvement of end-users, suppliers and perhaps most importantly from Microsoft which has major involvement and investment in OPC.

End-user membership in OPC

Our initial discussion related to the reality that end-users derive the major share of benefits from standards and interoperability. Today, end-users represent just 25% of OPC membership; the target for end-user membership should be a reversal of that ratio – at least 75% of OPC membership should be end-users.

Automation.com is working with The OPC Foundation to drive end-user participation. The cost of OPC membership is only $ 1,000.00 per year, and the benefits are significant. If your company is an end-user of industrial automation products, equipment, or services, you might wish to review the links below.