Deployment of standards-based, digital fieldbus networks has been steadily replacing combinations of proprietary local- and remote-I/O networks over the past decade, ushering in the plant floor information age, where flattened, streamlined organizations, offer the potential for everyone in the corporation to better understand the details of what does and doesn't make things work.
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AT A GLANCE
Digital fieldbus networks
Dynamic process measures
ISA S95: manufacturing/enterprise integration
IEC 61499: wire-independent protocol
Sidebars: SAP targets plant floor IEC 61499’s goal
Deployment of standards-based, digital fieldbus networks has been steadily replacing combinations of proprietary local- and remote-I/O networks over the past decade, ushering in the plant floor information age, where flattened, streamlined organizations, offer the potential for everyone in the corporation to better understand the details of what does and doesn’t make things work.
One of the downsides of the plant floor information age is that each time an “intelligent” instrument is connected, it provides the one or two values really wanted plus a hundred more values no one is quite sure are needed.
The result: businesses are drowning in data and thirsting for information.
We know how to link 50 devices. We can even link 50 networks of 50 devices each. The consequences of continuing to do that, however, have been ignored. It’s simply not wise to continue to save more and more plant floor data without first establishing an information architecture designed to efficiently manage and make use of the mountains of data today’s plant floor is capable of producing.
Information architecture
Performance measures (PMs) have long been used to indicate process/production performance. However, for PMs to positively influence a company’s bottom-line, PMs must be dynamic and reported in time for operators to influence process/production cycles, thus the information architecture must meet the needs of dynamic process measures (DPMs).
Frequently, DPMs are given titles such as “yield” and “efficiency” and are composite values developed using operating, costing, and energy related values.
Being able to consistently apply DPMs to improve a company’s bottom line requires an information architecture that:
Supports data scalability and abstraction;
Efficiently addresses the challenges of legacy systems; and
Capitalizes on available standards.
(See “CPAS information architecture” diagram.)
Scalability
Lynn Linse, an engineer at Digi International, believes significant improvements in how a business manages and uses its data are feasible when “true scalability” and “abstraction” are provided.
Linse says, “True scalability avoids having a system with 25,000 data values be 10,000 times more complex than a system with 25 data values. True scalability helps users manage data complexities by allowing zoom-in and zoom-out.”
“Data abstraction is also important,” says Linse; “It’s what allows the visualization of a production system as a large aggregate of many smaller, layered subsystems. For example, being able to easily integrate PLC-based controls provided by a skid-mounted equipment supplier into the main process automation system.”
Object (function block) architectures, such as those used by FOUNDATION fieldbus, most process automated system (PAS) manufacturers, and ODVA (Open DeviceNet Vendor Association), eliminate the need to manage individual data values and provide the ability to zoom-in/zoom-out. However, thousands of objects of any type can easily prove difficult to manage and still not address the skid-mounted controls integration example.
A potential solution for addressing data scalability and abstraction is emerging in IEC 61499- Function Blocks .
Under the guidance of IEC (International Electrotechnical Commission) technical committee 56, Rockwell Automation’s James Christensen is leading working group six to develop IEC 61499 as a wire-independent protocol designed to address the challenges of managing plant floor control systems including the data each produces. (See “IEC 61499 goals” sidebar.)
Christensen says, “IEC 61499 will first be adopted by the discrete industries as a way of integrating, configuring, and dynamically reconfiguring machines and systems built of intelligent, distributed mechatronic components. It’s economics and open-architecture design will help it penetrate the process industries, but at a slower rate.”
Several major suppliers are supporting the IEC 61499 development effort and Christensen reports its concepts have been tested in a European academic environment, but has yet to be applied to a real project.
In the mean time, users should continue to push PAS manufacturers for more robust third-party control system integration solutions.
Legacy systems challenges
Throughout the world, but especially in North America, large numbers of older (legacy) analog and digital instruments and control systems remain in-service with non-existent or loosely defined replacement plans.
Larry Komarek, Phoenix Contact automation manager, says, “Among the problems in managing plant floor data is that despite the availability of open system standards, control solution architectures remain essentially unchanged. Information from intelligent field devices, including transmitters, drives, motion control, vision inspection cameras, and micro PLCs is concentrated in a user-created database in the controlling PLC. From there it’s sent to cell-supervising computers, where another database is formed. Data are further transferred to additional enterprise databases—MES, LIMS, etc.—with each new database introducing opportunities for configuration and communication errors.”
What Linse says about true scalability and abstraction goes hand-in-hand with Komarek’s statement about database architectures: The answer doesn’t lie in storing more data. What’s needed is an information architecture that accommodates legacy instruments and systems.
Interface devices
John Ditter, Wago product specialist says, “Legacy systems designed, built, and installed prior to ‘open’ system standards present unique challenges when designing ways and means to share plant floor data throughout an enterprise. Often legacy systems use proprietary operating systems, networks, and protocols; have no remaining processor time; and/or have no room to add more memory. For owners of these systems, the options are limited. One solution is to add a data concentrator or gateway.”
Several manufacturers, such as Lighthammer, Phoenix Contact, and Wago, offer devices designed to connect to legacy systems and provide data in a variety of standard Internet protocols. Though each manufacturer’s product offers unique features, each utilizes industrial Ethernet as its physical layer.
Lighthammer’s Illuminator Manufacturing Intelligence Server uses standard Web browser technology to connect to the data sources and data types found on the plant-floor. Illuminator extracts, aggregates, and transforms data into plant-related information, such as asset utilization, production efficiencies and yields, inventory levels, order status, and quality and traceability data.
Phoenix Contact offers a range of serial data converters/isolators and Ethernet converters designed to extend, isolate, and protect industrial Ethernet and serial data networks. DIN-rail mounted, Phoenix Contact’s interface devices are suitable for industrial plant floors including hazardous area (Class 1, Div 2) locations.
Wago’s 750-841/842 Ethernet programmable fieldbus controller (PFC) provides a means of linking legacy plant floor data with enterprise systems. Each PFC serves as a smart gateway; connects serially; and uses Modbus/TCP, Ethernet I/P, or a custom Wago Ethernet-based protocol.
Obtaining and integrating data contained in legacy systems for inclusion into an information architecture doesn’t require replacing the system. It may be as simple as adding a data concentrator or gateway device.
Use ISA S95
As previously noted, plant-floors typically use multiple control systems from a variety of manufacturers, further complicating integration issues. Also, the greater variety of control systems deployed, the greater the implementation and maintenance expenses.
The family of ANSI/ISA S95 specifications provides a standard terminology and a consistent set of concepts and models for integrating manufacturing operational functions with enterprise functions.
For users, S95 specifications provide a means of identifying needs, reducing costs of automating manufacturing processes, reducing lifecycle engineering efforts, and enabling vendors to supply appropriate integration tools.
ARC Advisory Group VP of emerging technologies, Robert Mick, says, “Users new to ISA S95 are surprised by the lack of something to build. Rather than being a specification for defining messages and/or programming interfaces, S95 is an alignment process, where product manufacturers incorporate the S95 terminology and select models as part of their products, architectures, and activities. The specification includes several models and structures, and no supplier is likely to use them all.” (See “S95 supplier alignment matrix” table.)
Though the standard does not define a formalized protocol for information exchange, several ISA S95 committee members recognized that the creation of XML schemas could play an important role in making the standard “user friendly.”
Under the stewardship of the World Batch Forum (WBF), a working group developed the “Business to Manufacturing Markup Language” (B2MML) schemas. Released as a royalty-free implementation of the ISA S95 specification, WBF’s B2MML provides a set of XML schemas developed using the XML schema definition language.
Adding credibility to the ISA S95 specification and WBF B2MML schemas is recent indication that SAP AG has begun to address concerns about a lack of standards for efficiently connecting the plant floor to the enterprise business layer. SAP has begun addressing this situation by developing a roadmap that supports the ISA S95 specifications.
Businesses desiring to achieve maximum benefit from plant-floor generated data will most benefit from an information architecture that supports data scalability and abstraction, efficiently addresses the challenges of legacy systems, and capitalizes on available standards.
S95 supplier alignment matrix
Section
Defines
Supplier alignment example
Source: Control Engineering with data from ARC Advisory Group This matrix illustrates how suppliers can align product designs to match the ISA S95 specifications.
Part 1 / Section 5.1
Functional hierarchy and descriptions
Show general context and define production boundaries.
Part 1 / Section 5.2
Equipment hierarchy (consistent with ANSI/ISA S88 standards)
Use terms in documents and product user interfaces.
Part 1 / Section 6.1
Functional model
Standardize partitioning of product features and functions.
Part 1 / Section 6.2
Information flows between functions
Define corresponding message types in product.
Part 1 / Section 7
Object models, define classes and relationships
Standardize corresponding objects and structures in products.
Part 2
Objects and attributes
Provide defined object details.
Part 3 / Section 4.1
Manufacturing operations
Standardize partitioning of product features and functions.
Part 3 / Section 4.9
Manufacturing activities
Standardize structure of task within operating functions.
SAP targets plant floor
In the past decade, many businesses spent millions of dollars installing SAP AG enterprise resource planning (ERP) solutions.
Persons involved with past ERP deployments will recall that SAP consultants and implementers pretty much avoided discussions about integrating plant floor data. However, that doesn’t mean SAP wasn’t interested in the plant floor; it simply meant SAP wasn’t prepared to take on the plant floor. Times have changed.
SAP’s recent introduction of its Manufacturing Dashboard for Plant Managers reinforces SAP’s renewed interest in extending its reach to the plant floor.
The first release of the dashboard supports the plant manager role by providing real-time views of process/production operations. Using a configurable environment, the dashboard permits users to track 6-10 metrics with exception-based alerting, supports drilling-down on each metric to find root cause, and provides a library of pre-defined reports. (Later releases will be designed to support production supervisors and maintenance- and quality-managers.)
SAP recognizes that plant floor data plays a key role in efficient business decision-making. SAP also recognizes a consistent plant-floor infrastructure is necessary to support the dashboard. Because there are myriad plant floor hardware- and software-platforms, as well as communication protocols in use, SAP has developed its Operations Management Platform (OMP) as its dashboard delivery mechanism. It accepts data via OPC XML or other Web services-based applications.
Where such services don’t or can’t exist, SAP brings its NetWeaver platform to the plant floor. NetWeaver is the integration and application platform that forms the foundation of the mySAP Business Suite. NetWeaver embraces a host of Internet standards including HTTP, XML, and Web services. It also supports openness and interoperability with Microsoft .NET, Java 2 Platform Enterprise Edition, and IBM WebSphere.
For more information, visit
IEC 61499’s goal
Consider a plant environment where part of the control solution is being custom developed to suit the process in a modern process automation system (PAS). More conventional process needs (such as centrifuge, dryers, compressors, loading systems, etc.) are being provided by skid-mounted equipment manufacturers, usually using PLCs.
The manufacturers of the skid-mounted equipment have built-up an extensive product knowledge base including data-points, -relationships, -flows, etc.
The challenge isn’t linking/connecting the various skid-mounted equipment PLCs to the PAS. The challenge is integrating the entire knowledge base available from each of the skid-mounted equipment manufacturers into the PAS without encountering data re-entry and without introducing long-term software and data support issues. IEC 61499 is being designed to address that challenge.
Visit to learn more about IEC 61499.
Further reading: Bottom line, XML “A company must make every part of its operation more efficient in order to enhance the bottom line,” says Invensys’ chief marketing officer and author of “Bottom-Line Automation,” Peter Martin.
According to Martin, positively influencing a company’s bottom-line requires converging plant-floor data with quality and accounting data to form dynamic performance measurements (DPMs).
Following a brief historical review of past improvement methods, Martin’s book offers a practical, pragmatic, real-time strategy for measuring, analyzing, and improving process automation system performance to positively influence the companies bottom line. Martin’s strategy is based on the conclusions of applied research on process manufacturing operations; however, Martin’s methods perform best when data, necessary to update DPMs, are available in a robust, information architecture.
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