Paper-making factories are huge operations, often larger than a football field. The machines that turn wood pulp into paper have thousands of sensors and actuators that can be tough to control, even when equipment runs nearly nonstop.

Mohawk Fine Papers Inc. adds to that complexity by constantly stopping and starting its huge processing machines. The family-run company in Cohoes, N.Y., makes high quality papers used for prestige products such as annual reports and restaurant menus. Volumes are low and production runs may change eight or nine times per day.

“Our factory is very wired, with thousands of sensors that provide an incredible breadth of data,” says Paul Stamas, vice president of information technology for Mohawk. The majority of those sensors are accessed over wires. But for more than five years, a growing number have transmitted data over wireless links.

“We use Wi-Fi for sensors in areas where it’s difficult to run wires or where the environment’s too harsh, with too much heat or steam. In the warehouse, wireless is predominant. All the forklift drivers are guided to shipping packages with a wireless gun,” Stamas says.

Mohawk is part of a huge trend in industrial applications. Wireless communications are now considered reliable enough for use on factory floors, so they’re being deployed to provide inexpensive communications for sensors and other components that sit in places that are hard to reach with wires.

Many equipment suppliers feel this trend will dramatically alter the way that industrial networks are architected. “Wireless is a fundamental game changer in the industrial sector,” says Steven Toteda, general manager for supplier Cooper Wireless, a Cooper Bussman company in Dublin, Calif.

At Mohawk, the ability to add more sensors and other components is having a direct impact on bottom-line profits. “Paper manufacturing is very energy consumptive. We always want to see when there are alarms for excessive energy usages; that’s money going out the window,” Stamas says.

Wi-Fi steps up

As wireless technologies gain marketing momentum, industrial customers may follow the path that led many to Ethernet in wired networking. The rapid technical advances and price declines that come from high volume mainstream markets are making Wi-Fi (for Wireless Fidelity) more viable in all but the nastiest environments.

In just a few years, Wi-Fi has progressed from its initial implementation through the “n” version ratified last fall. Many technologists say that the revision will make Wi-Fi, officially known as IEEE 802.11 (a standard of the Institute of Electrical and Electronics Engineers), a much more viable alternative to proprietary frequency-hopping schemes.

“802.11n is absolutely a milestone,” says Paul Brooks, business development manager for networks at supplier Rockwell Automation Inc., in Mayfield Heights, Ohio. “It’s got features that make a huge difference, like retry mechanisms that mean you won’t lose packets in the air.”

Others agree that the upgrade brings a number of benefits, such as multiple in, multiple out (MIMO), that will simplify integration in complex industrial settings. “There are a lot of benefits with n, like MIMO, and if you have an n access point and have a couple older 802.11g devices, the entire network won’t drop down to the slowest speed like previous versions did,” says Tim Cutler, director of product marketing for Modules and Integrated Solutions Hardware at RF Monolithics Inc., a Dallas-based wireless products vendor.

Another change is that while earlier versions were limited to 2.4 gigahertz (GHz), the new standard works on 2.4, 3.6 and 5 GHz. That’s important in large applications in which a number of wireless networks may be needed. The 2.4 GHz level is limited to three channels, so only three networks can be configured. “With 5 GHz, you can have up to 22 networks,” Brooks says.
 
Not so fast

Though there are many benefits, companies that have already set up wireless networks may not race to make the transition from alternative technologies or earlier versions of Wi-Fi. Access points are typically installed in ceiling rafters, so replacing them requires a fair amount of effort. At Mohawk, the change probably won’t come until there’s a major remodeling.

“The communication that goes over wireless is different; we don’t need 100 megabits/second to say that we’ve just moved three cartons of this product from point A to point B,” Stamas says. “To change everything out, we’d have to bring cherry pickers into the plant, which is pretty costly.”

Alternative technologies may fit well for sensors and other nodes that only transmit small amounts of data. Wi-Fi packets are larger than those of ...