One technology getting a lot of attention is wireless as a means to communicate to anything anywhere (see: "Whither Wireless"). A key benefit is that adding a new data point requires little more than the sensor, radio and power supply. Undoubtedly sensors will continue to get smaller and use less power, yet provide ever-greater processing capabilities (see sidebar).
Figure 2 provides details on the wireless Ethernet protocols being developed and supported by IEEE. Range and data transmission capability vary considerably from personal area networks (PAN) for short distance communications through to the new regional area networks (RAN) standard under development. A significant number of protocols (the combination of hardware and software) rely on the IEEE 802.15 standard as the basis for the radio in the local sensor network backbone. The most widely used application of 802.15 radios is ZigBee — but Bluetooth and several other technologies shown (as well as cellular phone networks) employ the same unlicensed 2.4-GHz frequency bands. So, one of the challenges facing everyone will be how to use this limited bandwidth for all applications targeting this region of the spectrum as their base. The figure doesn't show all the physical connection solutions such as copper- (IEEE 802.3) or fiber-based transmission media that require gateways to convert between the various physical layers and protocols.
Having the means of carrying a signal from one place to another is only part of the solution. You also must have a common language or protocol so sensors can communicate with each other and controllers. The protocol likely to impact the process automation environment most is the forthcoming ISA100 standard. It will incorporate security features expected and required in today's communications while also having gateways to allow transmission and coexistence with other protocols using the same radio frequency bands. The low bandwidth carrier coupled with energy conservation measures will limit how much data can be transmitted.
However, moving up to a higher bandwidth such as IEEE 802.11 (the same wireless we use at home) or higher, we can transmit not only data but also sound and video. Many of us already have IP-based phones on our desks. It soon will be possible for all communications in a plant to be IP-based including video imagery. Video already plays a role in factory automation where vision sensors check for proper placement of labels on products and correct location and orientation of chips on circuit boards. At a process plant, video can serve, for instance, to monitor flares, level in a vessel or status of a pump seal.
Radio frequency identification (RFID) is another technology that will become increasingly popular. Most applications today use passive tags for tasks such as asset tracking (e.g., a pallet in a warehouse or a checked suitcase at Hong Kong's airport). However, development of active tags -- ones that can change depending upon the conditions in which they find themselves -- will accelerate acceptance. Several manufacturers already offer tools that combine the low energy features of RFID with an 802.11 interface to allow you to use the web to effectively keep track of anything or anyone. Active tags will enable you to follow an object over its full lifecycle. In addition, it's not too much of a stretch to expand the capability of active RFID technology to create simple sensors able to measure one or two parameters such as temperature and pressure or humidity in real time and update information on the RFID network whenever there's a change.
Plants soon will have access to ubiquitous and cheap data. This will make data mining increasingly important. Mining will move lower and lower in the enterprise -- down to the sensor level. Eventually sensor networks or at least their controllers will contain algorithms to correlate collections of data to create measurements that offer insights unavailable from individual data. Better interpretation of these data will differentiate successful world-class operations from the pack.
IAN VERHAPPEN, P.E., is director and principal consultant at Industrial Automation Networks, Inc., Wainwright, AB, Canada. E-mail at firstname.lastname@example.org.