Ethernet for the plant floor

What does 'Ethernet-enabled' mean? It means you plug it in, and that's it," begins Victor Wegelin, instructor of Industrial Data Communications, a training course (TS05) offered by the Instrument, Systems, and Automation Society (ISA). Wegelin emphasized the importance for plant engineers and others outside the IT department responsible for control system maintenance to understand the technolog...


What does 'Ethernet-enabled' mean? It means you plug it in, and that's it," begins Victor Wegelin, instructor of Industrial Data Communications, a training course (TS05) offered by the Instrument, Systems, and Automation Society (ISA). Wegelin emphasized the importance for plant engineers and others outside the IT department responsible for control system maintenance to understand the technology and issues involved in successful installation, commissioning, and operation of industrial control networks. Networks used exclusively for industrial control generally are used and maintained by people who are not communications specialists.

The seminar, held in June at the Hilton, Lisle, IL, explained the special requirements that industrial control networks have beyond business networks. According to Wegelin, industrial networks require predictable throughput and scheduling, extremely low downtime, and scalable size. These networks must be robust enough to operate reliably in harsh, and sometimes hazardous, environments. Most process network systems modify technology borrowed from business networks.


The bulk of the seminar centered on Ethernet and TCP/IP. Wegelin defined protocol as a "set of rules that determine how two devices should communicate." The tasks required of protocols are:

  • Error detection and correction

  • Routing messages through complex networks

  • Data encryption and security

  • Consistent signal levels among devices

  • Network addressing.

    • Layers

      There are many protocols. Trying to make sense of them is like eating alphabet soup. To organize them and understand how they interact, protocols typically are arranged into layers, grouping them by related tasks. For example, protocols that deal with the physics of message transmission, such as signal frequency, voltage level, and cable design, are grouped together.

      Wegelin likened Ethernet to the U.S. Postal Service. Send the message in the proper format and protocol, and it gets to where it is supposed to go.

      Protocols govern the way a letter is sent and received. The recipient receives and understands the message because proper protocols were followed. Not following appropriate protocols is like sending a message in a bottle β€” it may miraculously get to the intended recipient, but probably not.


      In 1977, International Organization for Standardization (ISO) developed a 7-layer model β€” called the Open Systems Interconnect Reference Model (OSI/RM) β€” for organizing data communication protocols. These layers are as follows:

      • Layer 1 = Physical

      • Layer 2 = Data link

      • Layer 3 = Network

      • Layer 4 = Transport

      • Layer 5 = Session

      • Layer 6 = Presentation

      • Layer 7 = Application

        • Wegelin discussed industrial protocol suites, such as Modbus, Modbus+, and AB DH+ as well as how they compare with commercial suites. He covered each layer of the model thoroughly, providing plant floor examples frequently. Wegelin said that it is important to understand that Ethernet is not a complete network on its own; it needs upper protocols.

          Wegelin concluded the seminar with a presentation about OPC ( He said, "Until the industry begins to get together on the application layer, we still have problems," referring to the many fieldbus protocols available to the plant floor. According to Wegelin, OPC may finally offer the industrial control compatibility that could call a truce in the ongoing bus war.

No comments
The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
2016 Product of the Year; Diagnose bearing failures; Asset performance management; Testing dust collector performance measures
Safety for 18 years, warehouse maintenance tips, Ethernet and the IIoT, GAMS 2016 recap
2016 Engineering Leaders Under 40; Future vision: Where is manufacturing headed?; Electrical distribution, redefined
SCADA at the junction, Managing risk through maintenance, Moving at the speed of data
Safety at every angle, Big Data's impact on operations, bridging the skills gap
The digital oilfield: Utilizing Big Data can yield big savings; Virtualization a real solution; Tracking SIS performance
Applying network redundancy; Overcoming loop tuning challenges; PID control and networks
Driving motor efficiency; Preventing arc flash in mission critical facilities; Integrating alternative power and existing electrical systems
Package boilers; Natural gas infrared heating; Thermal treasure; Standby generation; Natural gas supports green efforts

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
This article collection contains several articles on the vital role of plant safety and offers advice on best practices.
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.
This article collection contains several articles on strategic maintenance and understanding all the parts of your plant.
click me