What's on the wireless

From its origins in the IT world, Ethernet has changed considerably and is now penetrating almost every area that is amenable to networking. The key to the market success of tomorrow is making information available at every location, at all times, and along different channels. Ethernet-based data transmission is the most important medium for this, both today and in the foreseeable future.

Building on this strength, Ethernet is driving further and further into the industrial control arena, even down to the field device level. The use of Ethernet-based communications as the backbone of an automation network also opens up the possibility of implementing those networks wirelessly.

Wireless technologies for industrial applications are still in their infancy, but Ethernet offers a proven model in the IT world that can be easily adapted for the industrial environment. Of course there are hurdles of security and reliability to be overcome, but with huge numbers of industrial components from multiple vendors already Ethernet-enabled, wireless networking is an easy, logical next step. Most control systems can already connect to Industrial Ethernet, and even Web servers integrated into the controllers are available.

A recent study from market analysts Frost & Sullivan valued the global market for wireless industrial products at $117million in 2002, and expects this to quadruple between 2003 and 2006, defying the impact of a slowing economy.

Perhaps the most significant benefit of adopting wireless LANs on the plant floor is the reduction in the time and cost of cabling. The distributed control model for machines and plants has driven massive improvements in performance and productivity, but even with modern fieldbus systems the cabling requirements are extensive. Wireless networking can eliminate this problem at a stroke.

The attraction of wireless networking built around Ethernet-based communications in particular is the way in which it will enable companies to rethink plant management. For example, in industrial plants that are spread over extensive areas, the use of mobile Internet pads could significantly reduce the number of stationary PCs or human-machine interface terminals (HMIs) and the associated investment and follow-on costs.

Some 10-20% of maintenance overheads can be accounted for by journey times. The mobile terminal provides both the maintenance planner and the on-site maintenance engineer with all the information that previously had to be collected from different locations.

Similarly, machinery or plant operators who rely on HMIs to effect control actions could benefit from the use of mobile terminals, particularly where the machine in question or the section of plant being controlled extends over a large area. Rather than having to journey to the section of the machine where there is a problem, for example, the operator can take the mobile terminal to the area of interest, and make the control decision there, seeing the effects of that action in real-time.

With the power of the Internet on tap, wireless Ethernet is an attractive option for wireless networking, and the wireless LAN in accordance with IEEE 802.11 has become established in the industrial area, offering a substantially higher data rate and longer range than rivals such as Bluetooth. Users have security concerns, but there are already safety measures in place that make it relatively difficult to infiltrate the network. Such measures minimise the risk of hackers accessing the data, or other uninvited guests or unauthorised users logging into the network and effecting changes.

But security developments are on the horizon. The forthcoming IEEE 802.11I standard will set security higher than IEEE 802.11b with encrypted transmission, and manufacturers are creating the basis for making wireless LANs even more secure. The time is surely coming when wireless networking will be the preferred option in automation network structures.PE

Mark Freeman is with Siemens Automation & Drives.