Rival fieldbuses prepare for a wireless future

Rival fieldbus organizations the Fieldbus Foundation (FF) and Profibus & ProfiNet International (PI) are taking steps to ensure that they still have a role in any future Ethernet- and wireless-dominated world. To that end, FF is to conduct a series of end- user demonstrations of its wireless and remote I/O (WIO) developments to justify its claim that they tighten the integration of process instrumentation with the Foundation infrastructure. The list of end-user demonstration sites includes locations in the U.S, Netherlands, Brazil, Canada and Japan.  

Ineroperability

The WIO development project involves more than 25 companies including vendors, consultants and major end users from around the world and aims to develop use cases and requirements for high-speed Ethernet (HSE) remote and wireless communications that are interoperable using function blocks and Electronic Device Description Language (EDDL). WIO project teams include an HSE Remote I/O (RIO) team, an HSE backhaul team and a wireless sensor team and are responsible for developing device interoperability and network configuration solutions, validation of technical specifications and interoperability test and registration procedures. “We are pleased with the progress of our WIO project and the support it has received from the industrial automation industry,” said Fieldbus Foundation director of technology development Dave Glanzer. “WIO developments promise to advance the utilization of an open, interoperable fieldbus automation infrastructure incorporating both HSE and industrial wireless applications.”  

The WIO activity takes place in the context of the October 2008 agreement between the Foundation and ISA on the implementation of wireless backhaul transport networks and the ISA100 committee’s establishment in June 2008 of a Wireless Backhaul Networks Working Group. That Working Group, ISA100.15, is tasked with developing and maintaining a standard to address one or more dedicated or shared wireless backhaul(s) to support technologies running multiple applications, the first of which will be Foundation HSE.  

Process and discrete

PI has perhaps a more complex task than FF in that it has to accommodate the needs of both the process and the discrete manufacturing worlds. To that end, it has recently defined the upcoming work for wireless coupling of sensors and actuators in factory automation and has decided to adopt the IEEE 802.15.1 standard for that part of its work. That decision followed investigations which showed significant differences between the requirements for coupling sensors and actuators in factory and process applications. Not only do performance requirements differ but the standardized protocols for HART sensors and actuators in process automation and IO-Link in factory automation reflect their respective requirements. Thus while WirelessHART uses the IEEE 802.15.4 standard for transmission, the more demanding response time requirements of factory automation dictate the use of IEEE 802.15.1.  

PI opted for WirelessHART as the standard for process automation last year and has now decided that the IEEE 802.15.1 based WISA offers the optimum basis for developing the specification for wireless sensors and actuators in factory automation. A key issue that remains to be resolved is that of coexistence, not just with WirelessHART, but with the WLAN standard used for wireless transmission in ProfiNet systems. This will be ensured by making corresponding settings in the wireless sensor networks for process and manufacturing automation. The specification work for factory automation is already in hand with a target for completion of the relevant documents during 2009. Meanwhile the alternative and integrated uses of the radio technology for process automation (IEEE 802.15.4) and factory automation are being left open.  

The number of installed ProfiNet nodes worldwide grew by 40% from 1.1 million at the end of 2007 to 1.6 million at the end of 2008, leading PI to claim, with characteristic lack of modesty, that it is “the undisputed market leader in Ethernet-based industrial communication” and to predict that the node count will reach 3 million by the end of 2010. More surprising, perhaps, not least because of the prediction five years ago by the then Profibus PR supremo Geoff Hodgkinson that ProfiNet would overtake Profibus in terms of node count by 2010, is the continued growth of conventional Profibus DP which, while slowing in percentage terms ― 23% growth in 2007 against 21.5% in 2008 — nevertheless saw total node count reach 28.3 million by the end of last year. As a result, PI believes that it may pass the 50 million mark by the end of 2012, although the trend suggests to us that the crossover with ProfiNet could well be anything up to 12 years away.  

Growing almost as fast as DP is the number of installed nodes of the process industry version, Profibus PA, which was up 20% in 2008, reaching 880,000, while the combined node count for DP and PA in process industry applications is now said to have reached 4.8 million.  

On the safety front, PI claims 66,000 ProfiSafe systems incorporating a total of 630,000 ProfiSafe devices in the field by the end of last year. With ARC recently estimating the total market for bus-capable safety devices at 700,000, PI is claiming a 90% market share. 

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