“There are a couple of approaches to the solution. One is a tightly engineered solution for specific applications. This requires site surveys and installing the entire system at once. The second is to build intelligence into the environment and make the network robust enough to survive in a variety of industrial environments. There’s a lot of activity around Hart because it’s already used for continuous process diagnostic information. This protocol can be transported wirelessly. Another area of broad interest is machine health monitoring. This is an area of potentially huge energy savings. The lower cost of installing wireless monitoring can enable monitoring of smaller motors to increase the savings.”  

Wireless hurdles  

Tom Phinney, senior researcher at Honeywell Process Systems, takes note of potential problems with mesh networking, and especially with wireless sensors—those not connected to power supply wiring as well as communication wiring. “We’ve heard from users that mesh is not deterministic enough for some applications. Also, access points are usually good for 150- to 500-meter distances. Since many sensors are close to the ground, you may get many interferences. The major problem is with battery life. You may have to hire a contractor for a year, eight years after installation to replace all the batteries. Users want to install, then forget about it for 20 years. Security is another problem that must be addressed in mesh networks.”  

Phinney is active with the ISA SP100 committee working on an industrial wireless network standard. “ISA is unique among standards organizations in that it requires a strong end user voice. Vendors tend to say ‘Please accept mine so that I can sell more,’ while small companies say ‘Pick mine so I can live.’ End users don’t care about the technology. They just want compatibility with tools such as EDDL (Electronic Device Description Language), asset management software, training and so on. The fieldbus thing standardized how to describe all protocols. Now, any grad student could write a protocol converter. That’s important for a wireless world where there isn’t a wire for each protocol (e.g. Profibus, Foundation Fieldbus) but all protocols converge in a common backbone. Most users say they’re nervous about control on wireless. The future may be small wired clusters with wireless transmitter devices. Radio and MAC (Media Access Control) neutral is the only way to go for a standard. A low power 802.11 chip is coming that may put an end to the 802.15 world, since users are already familiar with it.”  

Finally, there are other wireless technologies widely used in the world. One is Bluetooth. Dave Wisniewski, product specialist for Rockwell Automation Inc., in Milwaukee, describes how it uses this wireless technology in its drives division. “We have a wireless input module (WIM) that the customer can install on the drive in place of ...