Back in the 70s, “Industry 3.0” was the name for the paradigm shift in manufacturing that embraced information technology to boost automation and enhance productivity, precision, and flexibility. As Industry 4.0 matures, the large-scale automation of industry through smart technology, machine-to-machine (M2M) communication, and machine learning (ML) is being realized. The key difference between the two is that while Industry 3.0 provided the information for humans to make better decisions, Industry 4.0 uses digital information to optimize processes largely without our intervention.
More than that, Industry 4.0 can now form a link between the factory design office and its manufacturing floor. By using M2M communications, computer-aided design (CAD) can talk to machine tools and directly program them to make parts. And machine tools can speak to CAD to let it know of challenges in the production process such that items can be modified to make them easier to fabricate.
The Industrial Internet of Things (IIoT) is the platform upon which manufacturers are building their Industry 4.0 solutions. An important role of the network is to form feedback loops whereby sensors monitor processes, and their data is used to control and enhance machine operation.
While implementing the IIoT is far from simple, perhaps the biggest challenge is the cost of investment. While the investment can be justified through cost savings brought by better design and manufacturing, yielding productivity increases and fewer product failures, anything that can reduce capital outflows is likely to accelerate Industry 4.0 adoption. One way to do that is to base a factory’s IIoT network on proven, accessible, and relatively inexpensive Ethernet communication technology.
Ethernet for Industry
As the most widely used wired networking option across the world, Ethernet brings good vendor support and IP interoperability. Moreover, one set of cabling can be used to carry current as well as data to power connected sensors, actuators, and cameras.
Featuring rugged connectors and cables, “Industrial Ethernet” builds on the consumer version of Ethernet to provide a proven and mature technology for industrial automation. Industrial Ethernet not only allows the transport of vital information, but also enables a remote supervisor to easily access machines, PLCs, and controllers on the shop floor.
However, standard Ethernet protocol is prone to lost packets, which increases its latency. That makes it unsuitable for synchronized and rapidly moving assembly lines. To overcome the standard protocol’s weaknesses, Industrial Ethernet hardware is teamed with deterministic, low-latency industrial protocols, including Ethernet/IP, ModbusTCP, and PROFINET.
Industrial Ethernet deployments use hardened versions of the standard product’s CAT 5e and, for certified Gigabit Ethernet, CAT 6 cable. CAT 5e cable, for example, comprises eight wires collected into four twisted pairs. The twisting limits signal interference (“cross talk”) between each wire pair. A pair offers both sides of a duplex connection. For high-speed systems, such as Gigabit Ethernet, all four pairs are used for carrying data. Systems with lower throughput requirements (up to 100 megabits per second) can operate using just two twisted pairs, leaving the spares for things like power or conventional phone services.
Proprietary Solutions Fill the Gap
One drawback of using CAT 5e cable for IIoT deployments is that it is overengineered for many tasks. High-speed Ethernet is all well and good when machine tools are being programmed from CAD, but is hardly required for a sensor reporting the speed of a conveyor belt. And much of an Ethernet-based IIoT is used for gathering modest amounts of sensor information to optimize the manufacturing process. That could mean a lot of capital expense tied up in kilometers of cable with engineering capabilities that are never going to be used.
In the cost-sensitive industrial sector such waste is generally avoided by turning to cheaper alternative. Instead of tying up money in expensive cables, manufacturers have turned to much-less-expensive proprietary fieldbus alternatives to connect sensors and systems that don’t need the full capabilities of Ethernet. These fieldbuses are typically used for applications such as industrial instrumentation and remote I/O and offer cable lengths of up to one kilometer and raw data throughputs of up to ten megabits per second. Many of these proprietary fieldbus options—for example, HART, PROFIBUS PA, and 4-20mA—use relatively inexpensive single twisted pair cable.
Today, factories implementing Industry 4.0 use standard Ethernet for things such as enterprise resource planning (ERP) and CAD, Industrial Ethernet for engineering operations and plant asset management, and proprietary fieldbuses for instrumentation and remote I/O. This is not ideal because while the first two systems play nicely together, the latter is not interoperable with them.
Introducing Single Pair Ethernet
IEEE 802.3cg, a recent Ethernet specification amendment, is designed to address industrial applications that are currently serviced by non-Ethernet fieldbuses. The amendment is gaining momentum because it allows all factory Industry 4.0 operations to use the Ethernet platform. Every piece of equipment, from the main factory cloud server, through remote terminals, and down to the lowliest temperature monitor, will be able to talk to each other through a single standards-based protocol.
A key component of the specification amendment is the Single Pair Ethernet (SPE) cable, which, as the name suggests, carries data over just a single twisted pair rather than the multi-pair CAT 5e cable of conventional Industrial Ethernet. This is a boon to factory owners because it significantly lowers the cost and bulk of much of their building’s communication wiring. Better yet, albeit with new Ethernet connectors, legacy proprietary fieldbus single twisted pair wiring can be repurposed for SPE use—there’s no need to rip out kilometers of old cable to replace with new ones.
IEEE 802.3cg also introduces two new physical layers (PHYs) to suit industrial applications and keep costs down. The first is for short-reach applications (up to 15 meters), while the second offers up to one kilometer reach and includes an optional amplified transmit level for increased noise tolerance and a low-power idle mode to save energy.
The Importance of ‘Right First Time’
Modern manufacturing demands precision and repeatability. A component or subassembly must be manufactured to tolerances tight enough such that they can be used in any of thousands of examples of an end-product and yet operate perfectly for years. As things get smaller or more complex, the greater the precision required; imagine consistently fabricating a high-end mechanical watch or the latest smartphone.
The IIoT can bring this precision by enabling real-time control and spotting deviations before they get out of hand. Getting products right the first time reduces consumer failures and endless warranty claims. It also saves money, and perhaps more importantly is more sustainable because making things correctly the first time as saves energy, emissions, and precious materials.
Single Pair Ethernet enables engineers to take advantage of Industrial Ethernet throughout the factory even for operation of the lowliest sensor. That makes it easier gather and analyze the deep data needed to both enhance manufacturing operations and maximize the impact of new technologies such as ML and AI.
Steven Keeping gained a BEng (Hons.) degree at Brighton University, U.K., before working in the electronics divisions of Eurotherm and BOC for seven years. He then joined Electronic Production magazine and subsequently spent 13 years in senior editorial and publishing roles on electronics manufacturing, test, and design titles including What’s New in Electronics and Australian Electronics Engineering for Trinity Mirror, CMP and RBI in the U.K. and Australia. In 2006, Steven became a freelance journalist specializing in electronics. He is based in Sydney.