CONTROL contributor, and Chairman of the Foundation Fieldbus User Group, Ian Verhappen, comments that lack of knowledge is the issue since the Reader's Choice Awards selected Ethernet as communications bus of choice when it only describes the Physical and Data Layers. This round of Fieldbus wars is being fought at the higher level - integrating data with the Enterprise and hence all the Profinet, HSE, and Ethernet/IP discussion. The EDDL/FDT skirmish is part of this battleground.
Verhappen continues, The Field Communications Device to Host battles are completed and each 'bus' has their niches and the cooperative project(s) as exemplified by the EDDL work confirm this. The Network level is where the struggle is now happening and many of the Industrial Ethernets available are all vaporware since few if any host systems support them.
The real problem, Verhappen insists, is that if hosts do support the Industrial Ethernet, it certainly is not in an open and interoperable fashion. End Users would like to see an interoperable control network layer based on standard protocols, he says, but at least for now each manufacturer is protecting that proprietary part of the system.
Verhappen points out the irony in the fact that todays process automation systems are standard on the bottom with FF, Profibus, and HART and standard at the top with web based HMIs on a Windows platform but proprietary in the middle. If they don't keep part of it proprietary they will not be able to sell as many services, Verhappen says, though he comments that this theory should be tested since most companies now rely on their automation supplier or system integrator to do all the system design, installation, commissioning for them anyway because they do not have the skills in house.
Verhappen concludes, If the automation companies are not careful, folks will simply use the Fieldbus of choice at the lower level and then 'standard' Ethernet web servers as the interface to this information and HTML/XML from their on up across multiple enterprises.
The other big player in this set of skirmishes, surprisingly, is the HART Communications Foundation, whose relatively ancient set of protocols was expected to wither away by now. Advances in the standard itself, coupled with the absolutely enormous installed field instrument base have made HART a viable candidate for plant digital communications in the process automation area.
Berra confirms this, now with his Emerson hat on. I have always viewed Foundation Fieldbus and HART as complementary, not competitive, he says. HART has a lot of value, particularly for existing installations. Most of the projects we do have a combination of HART and Foundation Fieldbus.
But Berra insists that HART is, at best, a stopgap. HART has some limits with data rates, and as diagnostics get more sophisticated, the limitations become more apparent.
With Profinet for process automation not yet available (is it vaporware, as Ian Verhappen suggests, or just not ready yet?), Andrew Bond may yet have the last word, at least for now.
On the specifically process front, the key decision to my mind remains whether and when Siemens decides that it has to back Foundation fieldbus in order to become a credible player in the international oil & gas, refining and petrochem markets.