At the most recent ODVA conference, where industrial
network topics are the order of the day (ODVA is the organization that supports network technologies built on the Common
Industrial Protocol, such as DeviceNet, EtherNet/IP, CompoNet and
ControlNet), one of the hot topics being discussed was wireless. One session in
particular, presented by Paul Brooks of Rockwell Automation and Paul Didier of
Cisco, focused on the current real world utility of wireless and the benefits
of moving to 802.11n in an industrial environment.
Though wireless network use is still very much in its infancy for industrial use, Brooks and Didier are confident that WiFi will follow Ethernet into greater use in automation and control systems. However, they expect that wide use of WiFi in the industrial arena is still several years off largely due to the level of existing investments in wired networks coupled with the fact that wireless technology capabilities tend to lag a bit behind wired.
In addition, Brooks noted that, from performance, energy and flexibility aspects, WiFi is not as capable as specific industrial wireless protocols such as WirelessHART or ISA 100. To illustrate his point, Brooks pointed out that, in control and safety applications, latency and fidelity remain the biggest challenge for wireless devices. Therefore, synchronization and motion applications tend to operate better when connected via wired networks.
But with an array of business drivers pushing greater use of wireless into the industrial area, such as the elimination of wires, portability/mobility of devices, asset tracking, remote monitoring and video surveillance, large market opportunities exist in industry for wireless devices. Therefore, device designers should concentrate on applications involving moving operators, moving machinery and applications where running wires is difficult and costly, suggested Didier.
"The key for wireless device designers is to ensure that the user experience is the same with a wireless device as it is with wired device," Didier said.
A large portion of their presentation focused on the benefits of updating to the 802.11n standard. Advantages for device designers inherent in the 802.11n include:
- MIMO (multiple inputs, multiple outputs), which ensures signals are received in-phase and increases receiver sensitivity;
- Maximum Ratio Combining - multiple signals are sent and combined at the receiver, thereby increasing fidelity;
- Packet aggregation - multiple packets are combined into one data packet, providing a big boost for network data management in time-critical industrial automation applications;and
- Backward compatibility with 2.4 GHz and 5 GHz as well as the 802.11 a, b and g standards. Didier added that, for optimal results, time-critical applications should run on 5 GHz with all else on 2.4 GHz to increase fidelity.