1 April 2001
Winding Through the "Open" Maze
Ethernet, Microsoft, Unix/Linux, networked storage, supply chain, B2B—all have standards champions.
Driven by users demanding equipment compatibility from all their suppliers, industry consortia are making considerable progress clearing paths through the "open standards" maze. However, when a user passes through one "open" door, other options often close behind.
For example, the OLE for Process Control, or OPC Foundation, is successfully using multi-vendor collaboration to develop open interfaces—"open", however, only to users willing to use interfaces based on Microsoft's OLE/COM technology. Virtually everything is "open" in the Linux community, but going exclusively that route can close out any functions Microsoft's technology might offer.
In the opinion of standards veteran Richard H. "Dick" Caro—vice president at ARC Advisory Group who has been deeply involved in fieldbus, Ethernet and related standards-making activities for many years—the word "open" has evolved to mean: "Controlled by an independent, non-profit organization in which anyone may become a member."
In general, manufacturing industry information technology (IT) standards consortia are active today in five broad categories: Ethernet-related, Microsoft-friendly, Unix/Linux-like, network storage, and supply chain/B2B.
To help Industrial Computing's readers sort out the options, here's an update on the major consortia and their activities.
Industrial Automation Open Networking Alliance (IAONA) is a trade group originally formed by NETsilicon in 1999 to promote Ethernet on the factory floor. Caro, IAONA secretary-treasurer and board member, said "vendor response was immediate and very positive."
A separate European group, IAONA-EU, was formed at last year's Hanover Fair, where more than 200 attendees were attracted to its first meeting. The presidents of both groups are employees of Jetter AG. The groups strongly cooperate and are expected to eventually merge.
Interface for Distributed Automation (IDA) Group) is a primarily Europe-based organization formed by Jetter, AG-E Automation, SICK, Phoenix Contact, RTI, Lenze, and, later, Schneider Electric. It has set as its goal creating a standard interface based on Ethernet TCP/IP for distributed automation solutions using IDA.
IDA's major focus is an object/function block library for robotics, motion control, and packaging. The major difference between those applications and the bulk of PLC programming is in microsecond-level synchronization, which IDA achieves across an Internet protocol (IP)-over-Ethernet bus using RTI's (Real Time Innovation's) middleware package called NDDS. According to Caro, the NDDS protocol, called publish/subscribe, "is not very different from that of Foundation Fieldbus."
Open DeviceNet Vendors Association (ODVA) was originally spearheaded by Rockwell Automation's Allen-Bradley unit to position their then proprietary DeviceNet protocol as an open bus. It has grown to become an independent, 300-vendor-member organization.
ODVA also controls another bus, Ethernet/Industrial Protocol (Ethernet/IP), positioned by Rockwell as the successor to both DeviceNet and ControlNet. Because of that, Ethernet/IP bus, ODVA, IDA, and IAONA recently signed a Memorandum of Understanding to cooperate on future developments.
The Object Library of DeviceNet and ControlNet, called Control and Information Protocol (CIP), contains all the classic PLC operations. IDA probably will adopt CIP and also add IDA's own robotics, motion control, and packaging objects.
OPC Foundation is an independent, non-profit organization comprised of about 270 manufacturers and factory and process automation application providers. Its charter is to develop, worldwide, a standard specification for multi-vendor interoperability in manufacturing and process industries, developing open interfaces based upon Microsoft's OLE/COM technology.
OPC Foundation's original library was called Data Access and contained objects to read and write PLC registers by number. OPC Foundation is currently in final development of a process control version in which Foundation Fieldbus function block access will be permitted via access to a "BlockID.Attribute.StructureElement"—a hierarchical addressing of a complex data structure permitted in C++ and defined in OPC by an XML data structure definition.
Linux International is a non-profit organization of more than 50 corporate sponsors and many more Linux fans worldwide. Not a traditional standards-making organization, its primary goal is to distribute information about Linux and how it benefits business and personal users.
The Puffin Linux Controller (PPLC) project is primarily an online user community seeking to create and distribute an open source programmable controller. The project originated from a discussion thread on Control.com's Automation List (www.control.com/control_com/alist/), a popular international noncommercial discussion list for industrial automation professionals started by Kenneth C. Crater, Control.com president.
Also not a classic standards-making body, the Puffin PLC project attempts to produce a working PLC-like program running on Linux but with a graphical user interface that can also run on Windows and Web browsers.
The GNU Project, conceived by Richard Stallman in 1983, has developed a freedom-of-use, non-proprietary system named "GNU'' (GNU's Not Unix) that is upwardly compatible with Unix. Once users have the software, they have the freedom to copy the program and give it away to friends and co-workers.
Networked Storage 'Hot'
In the opinion of Caro and others, networked storage is a current "hot" IT area, which was initiated by IBM with a private networked based on fiber channel.
Fiber channel's sole purpose was to be a SCSI replacement for long distance communications via optical fiber. Like SCSI, many computers could share a storage unit of terabyte capacity using a RAID 5 technology for fault tolerance, called Storage Area Networks (SAN).
However, "now that Gigabit Ethernet is available," Caro said, "there is a question on the use of fiber channel. The same fiber running gigabit Ethernet gives about the same performance as fiber channel, but avoids lots of obscure protocols in favor of more convenient IP-over-Ethernet protocols," he said.
Fibre Channel Industry Association (FCIA), which is focused on networked storage, is an international organization of more than 190 members and affiliates, including manufacturers, systems integrators, developers, systems vendors, industry professionals, and end users.
Storage Networking Industry Association (SNIA) is a not-for-profit standards organization made up of about 150 companies and individuals spanning virtually the entire storage industry. Its goal is to ensure storage networks become "efficient, complete and trusted" across the IT community. SNIA delivers standards, education and other services.
B2B Standards Emerge
RosettaNet is a non-profit, standards-making consortium with more than 350 participating company members. It is dedicated to collaboratively developing, open Internet-based standards that align high-tech business processes.
The Universal Description, Discovery, and Integration (UDDI) Project is a cross-industry initiative launched last September to accelerate and broaden business-to-business integration and commerce on the Internet. It was formed by a broad coalition of 36 businesses led by IBM, Microsoft, Ariba, i2 Technologies, and CommerceOne.
The UDDI standard creates a platform-independent, open framework for describing services, discovering businesses, and integrating business services using the Internet. It takes advantage of widely used Internet-based standards such as XML HTTP and Domain Name System (DNS) protocols. IC
Figures and Graphics
Jim Strothman is associate editor for Industrial Computing.
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