Information Use in an Enterprise
Figure 1. An organization typically employs data at several distinct levels.
Source: ISA-95.Meanwhile, some variant of SQL likely will emerge as the de facto standard for Level 3 and above. At these levels the time constant often is in the range of minutes, hours or days -- so the definition of "real time" is relative. What's important, however, is seamless bidirectional integration of data. Production orders and business data must flow down to the control system for optimizing manufacturing operations for maximum profit; actual output rates, inventory data and equipment health/status information must go up into the business logistics systems for scheduling work, process orders and minimizing operational expenses in the real time of business transactions.
Ethernet EverywhereNow that data have become more open and portable across multiple platforms and systems, the hardware problem -- sensing and gathering these data -- must be addressed. The probable solution will be "Ethernet everywhere" using the Internet Protocol (IP), which now is on version 6 (IPv6). A number of Ethernet appliances and most operating systems already support IPv6. What makes IPv6 important? Its most consequential feature is a much larger address space (the sets of three numbers between 0 and 225 you enter for LAN addresses) than that of IPv4. Addresses in IPv6 are 128 bits long compared to 32-bit addresses in IPv4. This means you will use a five number address mask such as 255:255:255:192:068. IPv6 supports a total of 2
128 (about 3.4×10
38) addresses -- or approximately 2
95 addresses for each of the roughly 6.5 billion people alive in 2006 or 2
52 addresses for every observable star in the known universe. Simply put, we shouldn't have a problem putting as many sensors as we need anywhere we need them, especially considering we can use the same tricks employed today to extend the capability of IPv4. 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).
Rethink Applications
As sensors become more rugged, reliable, smarter and smaller it becomes possible to embed them on the surface of vessels much like is being done today with skin thermocouples on boiler furnace tubes. In the near future, such sensors will be available to measure, e.g., pressure, strain and corrosion. There even will be miniature analyzers. A wireless gateway installed through a nozzle in a vessel will eliminate the need for any wires or connections inside the vessel itself.
A few years from now a reactor may boast IP-enabled sensors surface-mounted on its baffles. Pressure, temperature and other sensors, each about the size of a dime, will create a complete vessel profile. Their data will allow us to operate the reactor much closer to optimum conditions, resulting in higher yield at lower overall risk. In addition, we'll be able to detect hot spots, build-up, fluid maldistribution, localized corrosion and much more -- enabling much earlier identification of abnormal situations.
The possibilities for integrated sensors will be limited only by our imagination.
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.
