Ethernet marked its 40th birthday in 2013, a remarkable journey from a hand-drawn sketch to one of many networking protocols to the de facto networking standard for data centers and campus networks across the planet.
In recent years, Ethernet has made the jump from computers and servers to consumer electronics (TVs, Blu-ray players, game consoles), and there are plenty of places you might be surprised to find the little standard that could: telecom infrastructure, in-vehicle entertainment and, heck, even the Space Shuttle used Ethernet.
Over the past couple of years, I've spent a fair amount of time blogging about Ethernet in the data center. With Embedded World coming up next week in Nuremberg, Germany, however, I thought I’d take some time to discuss one of those areas where you might not expect to find Ethernet – the machines and robots that make up the world of industrial automation.
It’s a great example of how adaptable Ethernet is and how it can be used in applications beyond the data center.
OK, for starters, what is industrial automation? Here’s a quick definition from PC Magazine:
Making products under the control of computers and programmable controllers. Manufacturing assembly lines as well as stand-alone machine tools (CNC machines) and robotic devices fall into this category.
Over its long history, Ethernet has shown an amazing ability to accommodate expanded functionality. So, how has it evolved to make it a great choice for robotic automation?
The first step was to augment the standard TCP/IP best-effort protocol with other industrial protocols that provide increased packet delivery predictability and performance.
These are needed because on a high-tech assembly line, each machine has a specific task (or tasks), that needs to be completed in a specific order. You've seen the videos of the conveyer belt moving along as jointed, robotic arms whir in and out doing their work, right? That’s high-precision stuff.
With TCP, data packets can arrive at a destination out of order, which is no problem for many network applications, but causes havoc in industrial applications. So industrial Ethernet turns to purpose-built protocols such as PROFINET and Ethernet PowerLink to provide determinism. Intel has been working closely with leaders in industrial Ethernet to ensure that Intel® Ethernet Controllers bring outstanding performance to industrial applications.
PROFINET utilizes three protocols simultaneously, applying the right protocol depending on the application requirements. TCP/IP is used if the application needs a 100 ms response time, a real-time (RT) protocol kicks in for data needing 10 ms response times and, finally, the PROFINET isochronous real-time (IRT) protocol is used for data with cycle times of less than 1 ms. Want to see PROFINET in action? Check out this video showing a robot solving a Rubik’s cube from last year’s Embedded World.
Ethernet PowerLink uses a centralized Ethernet polling approach that is combined with time slicing to differentiate between data types and ensure that the most time-sensitive data gets to its destination. The PowerLink managing node is a central controller that initiates a data cycle by polling every node in the network. The poll features two data phases; an isochronous phase for all real-time data and an asynchronous phase for ad hoc data. Separating the two makes it easier to prioritize the real-time data and deliver it in less than 200 microseconds.
The availability of an isochronous data channel in both of these protocols helps to eliminate jitter – the packet transmission delay caused by congestion and other factors. With robots depending on each data packet to know what to do next, jitter can upset the entire operation.
Maybe industrial Ethernet seems boring, but I have to admit that having robots on the network is cool. Industrial Ethernet is also a foundational element of the emerging “Internet of Things” that lets machines and non-traditional connected devices leverage the ‘Net for communication. To find out more about Intel’s technology for the industrial Ethernet and the Internet of Things see our intelligent systems page.