Ethernet is everywhere in the business environment. In factory and process automation it even extends down to the device level. Industrial versions of Ethernet offer more rugged hardware, industrial protocols and real-time TCP/IP extensions. The question of whether Ethernet will penetrate down to the field level has become closely linked with real-time issues, plus service, calibration and diagnostic messaging within the device itself.

Extensions of the old Fieldbus wars

Most suppliers profess to support all major industrial networks to provide the device interoperability which end-users expect. But some skirmishes continue – e.g. the battle between EDDL and FDT/DTM solutions for manufacturer-independent integration of field devices. In my opinion the objections are not related to technical performance, but are primarily commercial – coming from leaders who want to retain their advantages rather than diffuse them by allowing competitors to participate through a technical “back door”.

The Wireless Revolution

• WiFi (IEEE 802.11) is common with laptop computers and can be used for PDAs and personnel equivalents in industrial applications. Operating range is limited to a few hundred feet, or less, depending on obstacles. For a typical factory or process plant, repeaters or extenders may be required to facilitate reliable reception throughout the operating environment. WiFi has fast throughput and bandwidth of 10 MHz or more, but consumes resources (memory, battery life) which typically limit applications to portable equipment that can be recharged often.
• While Wifi is merely a 'wireless version of a broadband extension cord with a short range, WiMax provides high-throughput broadband connections over longer distances. Several industrial product developers are offering WiMax for factory and process plant operations.
• Bluetooth, named by the original Scandinavian developers after a Viking chieftain, uses less resources and power than WiFi, but has a transmission range of only about 20-30 feet. It is best suited for elimination of cables between line-powered equipment and close-by extensions (e.g. printers). In factory and process plants, it is typically used to connect control-room devices.
• For connecting large numbers of I/O points in factory or process installations, Zigbee networks are quickly coming to the fore. The name is a reflection of how the network operates – using zigzag communications like a honeybee, depending on other network nodes to provide reliable connections. Built on top of the IEEE 802.15.4 standard, Zigbee uses license exempt communications frequencies (2.4 GHz global, 915 MHz in the US, 868 MHz Europe). The significant advantages are very low power (long battery life – battery powered devices can “sleep” and “wakeup” on demand), minimal resource requirements (memory and processing power), transmission range (up to few hundred feet), adequate bandwidth for industrial applications (20-200 kB/sec), unlimited network size (up to 64,000 nodes per network coordinator, extending to millions of devices), high reliability (not susceptible to network disconnects) and low cost. Look for Zigbee to generate significant growth in a variety of industrial applications.

The future of the industrial automation environment holds the potential for inexpensive, yet significant, installation of sensors throughout a plant to yield a vast array of information to improve operations and profitability. Companies and products that fail to exploit this next wave of the digital revolution will simply obsolete themselves.