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How EtherCAT levels the digital playing field for manufacturers

Published: 8 January 2019 - Sarah Mead

For many manufacturers, the first steps to digitalisation are often wrought with uncertainty, posing questions like, “What network architecture will work best? What controllers, hubs and switches do we need?” and “How do we build a system with real-time communication?” For many, going back to basics, and considering the underlying fieldbus technology that many of today’s digital platforms are built on, is perhaps the best first step.

It doesn’t matter whether you’re a packaging contractor running dozens of robots for pick and place applications, a busy airport operator delivering round the clock baggage handling systems or an automation giant with advanced motion control systems in place. The reality is that we all want the same thing; to run efficient, robust and often scalable networks that can increasingly handle high-volume processes, which are digitally-connected.

While the allure of smart factories and features such as remote monitoring, predictive maintenance and real-time motion control have convinced many manufacturers to take the leap of faith, they face challenges. These include complex system architectures, hardware miniaturisation, the blurring lines between ERP and MES and the need for extra hardware such as switches, hubs and network cards to make all this possible.

Rather than increase complexity, it’s advisable for business leaders and engineers to go back to basics and first consider their network from the physical, field level. While fieldbus and industrial ethernet-based systems have been around for many years, the best ones are those that are continually and openly developed to keep up to date with the advanced needs of today’s modern, digital applications.

EtherCAT is the best example of this, and quite possibly the last fieldbus you’ll ever need. Introduced by Beckhoff in 2003, EtherCAT is a high performance, low cost industrial ethernet that has evolved to become a globally recognised, open international standard now developed by the EtherCAT Technology Group (ETG).

What makes EtherCAT so special is that while it uses the same low-cost hardware and cabling systems of well-known ethernet technology, it replaces the traditional TCP/IP technology stack with a real-time system that is arguably the fastest, most robust ethernet platform on the market today.

In a network made up of a central controller (a master) connected to a series of drives or nodes (slaves) a data signal would typically be transmitted and received to and from each node, taking time to be processed by the CPU and returned to the controller.

This process uses lots of bandwidth as multiple frames of data need to be sent, received and processed. It’s also slow, as data is processed through each layer of the technology stack. EtherCAT solves this problem by taking a different approach.

With EtherCAT, a single ethernet telegram or frame is enough to send and receive control data to and from each node. In this process, each node reads the data addressed to it and writes it back to the frame “on the fly” while the frame moves downstream.

The result is a deterministic, synchronous, real-time system that increases the data rate to over 90 per cent. Combined with ethernet’s duplex feature, which allows signals to be sent and received simultaneously, this means the effective data rate can be over 100Mbits/s.

This master-slave relationship also allows EtherCAT to be networked in any topology, whether it’s line, tree, star or ring. Where engineers may have traditionally cascaded field devices using switches and hubs, these are now integrated into EtherCAT’s I/O modules, meaning that they can be eliminated entirely, further reducing the cost of infrastructure.

These combined features mean EtherCAT can process 1,000 I/O points in 30 microseconds and communicate with 100 servo axes in 100 microseconds, with a single ethernet frame being capable of exchanging the equivalent of almost 12,000 digital inputs and outputs.

So, what does this mean for manufacturers? Well, for most, it means being able to level the digital playing field. If you’re a robot manufacturer, for example, EtherCAT could, in effect, let your controller combine fieldbus functions for your HMI, your vision system and your simulation software without the need for additional hardware.

While the first steps to digitalisation may seem wrought with challenges, this isn’t always the case. Having found the only fieldbus you’ll ever need, you can at least begin to answer some of your original questions and ask more interesting ones like, “how big can we go?”



 
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