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A recent research report from IMS Research (part of IHS Inc) suggests that the use of Ethernet networking technology for motor drives and motion control will more than triple by the year 2016. New Ethernet nodes are, according to the report, likely to account for over 20% of the new networked motion-control products in 2016. At the same time, the number of Ethernet nodes in process industries is set to double.
By Taner Paca
This growth will come at the expense of conventional fieldbus technology, which is likely to grow at a much slower rate until the year 2016. And it’s a process that is likely to continue: according to the author of the report, IHS analyst Tom Moore, “It is forecast that in 10 to 15 years Ethernet will have replaced fieldbus as the mainstream networking technology for motor control products.”
So how has this relatively sudden increase in the popularity of Ethernet technology come about? To explain that, a bit of background is necessary. When Ethernet was introduced in the early 1980’s, it was designed to link computers together in Local Area Networks (LANs), and it initially competed with other networking technologies such as Token Ring and Token Bus. ‘
However, once the IBM PC was introduced – and a PC Ethernet adapter quickly followed – the simplicity and versatility of the technology made Ethernet the accepted standard within ten years, so that by the mid-1990s, just about every PC and peripheral had Ethernet connectors built into their motherboards. This was helped by a conscious effort on the part of computer manufacturers and international organisations to establish a formal standard, which resulted in the general adoption of the Ethernet 802/3 standard.
In the industrial networking environment, fieldbus initially developed more or less in parallel with Ethernet, using a range of protocols and technologies to enable a range of discrete devices to be connected within the industrial environment. However, there were many competing technologies for fieldbus and although there were some attempts in the early days to create a unified communications protocol, it didn’t happen. There are good reasons for this. Apart from anything else, the type of application has a fundamental impact on the way that fieldbus is implemented. For example, fieldbus technology in a manufacturing plant is different from that used in an oil refinery, largely because fieldbus is intrinsically a hierarchical system, and the number of layers in the hierarchy affects the deployment of the technology.
This can present problems, especially for complex motion control applications, where increased performance and shorter cycle times are necessary to maximise the increasing speed and versatility of controllers. Traditional fieldbuses have become the bottleneck in these systems, simply because they are not fast enough.
This is where Ethernet-based networks come into their own. Although it was originally devised for use in PC LANs, Ethernet has continued to develop over the years, largely driven by the increasing use of digital technology in industry and in the domestic environment. As a result, Ethernet technology has become widely used within fieldbus networks, and protocols such as EtherCAT (the last three letters standing for Control Automation Technology) have spurred this development. Indeed, as Tom Moore of IHS notes, “Ethernet…is very well suited to drive and motion control applications. The growing number of Ethernet protocols, which are high-speed, deterministic, and low jitter, mean its application has never been easier.”
Ethernet has always been easy to install, and long distances between nodes – a characteristic of many industrial applications – is no real issue. This saves installation time, and ensures speed, precision and flexibility during operation, while enabling remote maintenance through a suitable controller.
In turn, manufacturers such as Omron have created devices and systems with fully open communication, so that an advanced motion-controller such as the Trajexia-PLC has in-built Ethernet/IP, with Profibus-DP, DeviceNet and CANopen options available for fieldbus connection.
The process developed further with the introduction last year of the Omron Sysmac automation platform, which uses one software to integrate motion control, logic sequencing, sensing and networking. Devices such as the NJ controller, part of the Sysmac suite of products, have been developed with built-in EtherCAT and Ethernet/IP, which enables machine control and plant data management through a single platform.
And this is perhaps the source of the greatest impetus for the increasing use of Ethernet in industrial environments. The opportunity to manage everything from machines to back-office functions using similar control protocols – even a single computer terminal – is going to improve plant efficiency, and substantially reduce both downtime and costs. It’s a point echoed by Tom Moore, who says that the increasing use of Ethernet, at the expense of conventional fieldbus technology, “can only be good for the unification and simplification of networking solutions; driving down costs and increasing up-time”.