Ethernet at the tipping point: Reducing the risk of change
The moment when more people want the benefit of new technology than fear the cost of change is called the tipping point. That moment has come for Ethernet as a device-level network. This year's introduction of the first industrial control devices with an embedded Ethernet switch marks an important milestone in this process.
The moment when more people want the benefit of new technology than fear the cost of change is called the tipping point. That moment has come for Ethernet as a device-level network.
This year’s introduction of the first industrial control devices with an embedded Ethernet switch marks an important milestone in this process. This advancement dramatically reduces the cost of using Ethernet for machine control, bringing the cost in line with that of fieldbus.
Embedded Ethernet switches at the device level will make Ethernet more affordable for controlling industrial machines and processes. The common star topology requires expensive external switches. Embedded switches allow Ethernet implementation in a wide variety of other topologies, such as daisy chain, ring or mesh. Device-level embedded switches will reduce the cost of each connected device from about $40 a port to less than $2 a port.
Embedded switches also create network environments more familiar to plant and control engineers. Because most maintenance and design people are accustomed to networks with a line topology, it will be easier for them to move to Ethernet if they are not required to move to a star topology.
Although fieldbus networks will continue to be used, their ultimate demise is inevitable. According to a recent ARC Advisory Group report, the lower total cost of ownership and improved adaptability and flexibility of Ethernet is rapidly driving the adoption of Ethernet as a device-level network. The next generation of plant engineers will view Ethernet as the backbone of their operations.
While the continuing advances in Ethernet technology for industrial applications are important, a number of business and human factors are proving even more powerful in making the rapid evolution to Ethernet inevitable. Efficiency is the name of the game for business today — whether it’s defined as greater throughput, reduced downtime, better product quality, faster delivery of products to customers or lower operating costs.
Achieving these business goals requires an integration of diverse operations and a flexibility of response that is not achievable with traditional fieldbus technologies. It requires a common language and a seamless flow of information between manufacturing and management.
Consider the operation of the human neural network, where nerve endings in the fingertips instantly transmit information from the environment to the brain, which in turn sends messages back to the hand to move, clench or open. Imagine if the hand was resting on a hot stove, yet a translation center in the wrist took minutes to decode messages from and to the fingers. The result would be a badly burned hand. That’s what is happening with today’s fieldbuses.
Immediacy of information is the key to improving operating efficiency — whether it’s the human body or a manufacturing process. Ethernet and related information technologies will make real-time monitoring and control of processes possible from anywhere. For the plant engineer trying to keep everything up and running despite a shrinking staff, it will mean achieving greater control of the plant than has ever before been possible.
With Ethernet you can see into the operation of any machine or process on the plant floor from your laptop or hand-held device. You can get an email alarm on your cell phone when you’re miles away from the plant. As any plant engineer recognizes, averting a shutdown with a rapid response is a powerful incentive for change.
Equally important is the human factor. Plant engineers know first-hand the difficulties of attracting, training and retaining skilled personnel. The cost of training is one of the biggest barriers to change on the plant floor. That, and a parallel line of thought that says, “If it isn’t broken, don’t fix it,” has delayed new technology adoption at many plants.
The coming retirement of most of today’s plant engineers over the next decade will create an entirely new set of expectations on the plant floor. The next generation of plant engineers will come from the world of computers. Instead of a few thousand new graduates trained in traditional control technologies, there will be tens of thousands of potential job candidates who are comfortable with the Internet and drag-and-drop programming.
Not only will the talent pool be dramatically larger, but the training costs will also be less. If everything has the same foundation — whether it’s a computer or a control system — then everyone will speak the same language and have the same expectations. As English has become the international language of business, so Ethernet and IT will be the international language of the plant floor.
The potential cost savings will be equally dramatic. An average SCADA system, for example, costs $15,000, plus another $14,000 for the data historian. Every additional seat adds to the cost. Then there are the annual fees for software license renewals and software updates. The average plant pays thousands of dollars every year for the “privilege” of using their SCADA systems.
The adoption of Ethernet at the device level has begun to change that equation in the plant engineer’s favor. No software license is required for the Web browser built into every computer, providing license-free access to a plant’s SCADA information.
Also reducing costs is the use of the Modbus Ethernet TCP/IP protocol, which is free, unlike the proprietary industrial Ethernet protocols with their annual subscription fees that are sold by many automation suppliers. Modbus TCP/IP is now the most widely adopted protocol for Ethernet access for industrial applications. For a large corporation with multiple plants, the savings in software licenses from using Ethernet and Modbus TCP/IP could amount to tens of thousands of dollars every year.
Reducing the risk of change
Embedding an industrial switch in the Ethernet interface on a PLC, drive or other control device will give plant engineers the flexibility to choose the best network topology for their applications. What’s more, new cabling and infrastructure components will make these device-level Ethernet architectures suitable for both IP20 and IP67 environments. Ethernet switch technology has also become very fast, making it suitable for many different control applications.
Using “quality of service” to prioritize control-related message flow, for example, up to 32 devices can be daisy-chained with a delay of less than one millisecond. Greater system reliability will also be assured because faulty device replacement works the same way in daisy-chain architectures as in star topologies. The system recognizes that the new device is the same type as the faulty device. It automatically assigns an IP address and downloads configuration setup parameters, saving time and minimizing downtime.
These technology advances will reduce the risk of change. By their willingness to embrace rather than resist the coming changes, plant engineers will be able to more quickly reap the rewards of greater efficiency and lower costs for themselves and their companies.
|Michael Sullivan is a strategic marketing manager for Schneider Electric’s Ethernet systems group. He has worked with Schneider Electric for 10 years, focusing on Ethernet systems for the last two years. He has a master’s degree in manufacturing management, a master’s in business administration and a bachelor’s degree in electrical engineering, specializing in control systems. He can be reached at (978) 975-2823 or firstname.lastname@example.org .|