Is “Industrial Wireless” A Myth?

Oct. 10, 2012
Mike Fahrion discusses Ethernet for industrial applications and how it can be implemented with cellular and Wi-Fi.

In most ways, industrial Ethernet is more or less the same thing that you’ve got running through your home or office. It’s the same basic technology and the same chipsets. The only real difference is the quality of the connected devices. Things like hubs, routers, and switches in industrial environments must be able to stand up to shock, vibration, and temperature extremes on a daily basis. The consumer-grade gadgets that we use in our homes and offices aren’t designed or built for that kind of abuse.

Industrial Ethernet also needs to address a couple of other issues that aren’t normally much of a factor in home and office installations. For example, industrial cable runs are often quite lengthy, and many of the connected devices probably will have different ground potentials. The risk for ground loops, electromagnetic interference (EMI), electrostatic discharge (ESD), and other unwanted power surges is far higher than it would be in a home or office installation. (Consumer grade USB is particularly susceptible.)

As a result, industrial networks normally employ heavy-duty surge suppressors, and they place electrical isolators at strategic locations all around the network. Quite often the isolation will be built right into the devices that reside at the network focal points, like switches and serial servers. You’ll see plenty of dedicated inline and panel mount isolators as well.

Industrial networks also have to do a lot of media conversion, from fiber optics to copper cable, for example, or from serial data communications protocols to Ethernet. There’s probably some fiber to copper media conversion happening up on the telephone pole that provides your DSL or cable television link, but only a very large office network needs fiber optics, and home networks don’t need media conversion at all.

Aside from the environmental concerns and the need for various kinds of media conversion, however, industrial Ethernet behaves just like your home network. The same features that make Ethernet so useful in homes and offices make it infinitely more attractive than proprietary fieldbuses.  

“Industrial Wireless” Will Be No Different

The wireless technologies that are going to dominate factory floors soon will be the same ones that we use in our homes and offices. Cellular, Wi-Fi, and Bluetooth will be the base technologies that dominate the wireless world in the near term, whether it’s for IT or industrial applications. Niche technologies will survive for a while, but in the end they’ll be backed into a price and performance corner. Cellular, Wi-Fi, and Bluetooth ship in volumes that are orders of magnitude higher than anything the small, proprietary vendors can achieve, and with similar deltas in R&D budgets.

Cellular-based rugged Ethernet, already widespread in applications like fleet management and intelligent traffic control systems, will quickly expand into most other industries as well (see the figure). The price, convenience, and coverage provided by the cellular networks make cellular data networking very attractive compared to alternatives like fiber-optic buildouts. The cellular carriers will do everything they can to encourage this trend. Talk time has flattened out and the cellular providers know that if they want to continue to grow, cellular data plans that encourage machine-to-machine (M2M) device connectivity and networking are their only alternative.

The cellular telephone system provides a way to network remote sites and M2M equipment, as in this interactive traffic control system deployed across a geographically dispersed area in Europe. To establish two-way communication between remote devices and the monitoring center, UMTS/HSPA+ cellular routers were paired with security cameras, meteorological sensors, and dynamic road signs to access and analyze traffic and weather conditions and alert drivers in real time.

Just like wired Ethernet, wireless Ethernet will be used to keep the huge installed base of legacy devices connected and communicating via wireless media conversion. There are already devices on the market that enable serial equipment for Wi-Fi, for example, creating local wireless “hotspots” that technicians can access with their laptops, smart phones, and tablets just as easily as consumers access networks in the local coffee shop.

Called “Wi-Fi access points,” these devices come as embeddable modules or as boxed units for external use and are purpose-built for M2M applications. Expect to see this trend continue as wireless Ethernet takes over more and more of the tasks that used to be performed via fiber optics or copper cable.

Like wired networking devices, wireless equipment will need to be ruggedized for industrial use. And as the network edge expands to include increasingly remote locations, there will be a need to consider alternative wireless backhaul. A cellular router, for example, can be equipped with multiple SIM card ports, allowing it to automatically switch to an alternative cellular provider if communications with the primary provider should fail.

As the software and hardware have continued to improve, the interfaces between wireless, copper, and fiber have become quite seamless. Connecting to that wireless printer on the other side of your office isn’t all that different from connecting to a remote sensor on a pipeline half a continent away. In the end, whatever the connections or attached devices may be, it’s all just Ethernet.

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