Wireless merger 'won't happen'
23 Nov 2009
Lisobon - An International Society of Automation (ISA) sub-committee has concluded that merging WirelessHART and ISA100.11a would be impossible because the technical differences between the two wireless standards are too large to bridge, Honeywell Process Solutions (HPS) officials reported at the company’s recent EMEA users’ group meeting in Lisbon.
The decision was stated to have been reached by the ISA100.12 subcommittee, which for the last year has been working on developing a converged standard for the two wireless technologies, HPS. The committee, whose members include representatives of companies from both camps, had instead recommended a dual-boot approach, whereby devices will be equipped to operate to either standard.
“The ISA100.12 committee concluded that the merger of the two technologies will not happen. They are so fundamentally different that it would be impossible to bring them into one standard,” Honeywell Process Solution’s Jean-Marie Alliet reported at the company’s EMEA user group meeting in Lisbon. Honeywell is a strong proponent of the ISA100.11a standard - a position also recently adopted by Yokogawa.
According to Alliet, the ISA subcommittee will deliver a best practice paper for the development of field devices that can be used either as WirelessHART or ISA100.11a equipment. This work, he expected, would be finalised next year.
The test specification for WirelessHART field devices, published in May and for which devices are now available from certain vendors - most notably Emerson - is aimed at the same applications as the ISA-100.11a standard. The ISA standard was introduced in September, but complying devices won’t be available until next year.
Efforts to achieve a merged standard follow growing concerns among end users that competition between both specifications would impede the application of wireless technologies in process automation.
NAMUR, the international association for end-users of process automation, has stated: “A competition of standardisation does not make sense, neither for vendors nor users, since it obstructs value-adding competition for solutions.”
German-based NAMUR has also recently stated that merging both specifications into a single international standard would be feasible - particularly, it said, because their technological basis is the same, using the 2.4GHz ISM band in line with the IEEE 802.15.4 standard.
Namur subsequently announced that WirelessHART technology meets the requirements for wireless sensor networks in process applications. The decision followed a field test, conducted at the BASF facility in Ludwigshafen, Germany included laboratory evaluation of performance characteristics and several implementations in operating process-plant environments.
The Namur field test used Wirelesshart products from ABB, Emerson Process Management, Endress and Hauser, Mactek, Pepperl and Fuchs and Siemens to evaluate and verify Wirelesshart compliance with Namur Recommendation NE124, ‘Requirements for Wireless Automation’ and Namur Working Document NA115, ‘IT Security for Process Automation Systems’.
After conducting the multi-vendor field test, Namur reported that WirelessHART provides the flexibility, security, robust performance, coexistence with other radio technologies and device interoperability within a Wirelesshart network that its members should expect.
