The December issue of Control Magazine contained an article http://www.controlglobal.com/articles/2009/ProcessAnalyzersPlay0912.html of interest to automation professionals involved in data integration and as the title of this blog implies, that is Xi (pronounced “X-EYE”) as a new version of OPC. As a process analyser professional, it interested me to see that this technology is initially believed to have significant impact to the PAT initiative and then two “minor” items in the associated sidebar explaining the technology a bit further caught my attention. These were the words, “patented” and “may not be available on some of the older Microsoft operating systems” which in the case of control systems could be just what is being used. After some investigation I was able to see that in both cases it is a ‘false alarm’ this time around. Here is the explanation I was able to obtain.
1. Emerson holds the security patent referenced in the article and used in XI and they are allowing it to be used royalty-free with all implementations of Xi.
2. OPC Xi provides for the automatic discovery of servers via the Xi Directory server. The Xi Directory server supports both manual and automatic configuration with automatic configuration using Microsoft PNRP (Peer Name Resolution Protocol). PNRP allows Xi servers to automatically register themselves with the Xi Directory server, while manual configuration allows the System Administrator to customize the list of servers discoverable by clients and to manually add servers that do not support PNRP. PNRP was introduced and patented by Microsoft in 2006 and was included in Windows XP Service Pack 2 so if your control system is running an earlier Operating System it is likely that you will have to follow the manual configuration route.
More information about Xi including links to how it works can be found on the dedicated web site at http://www.expressinterface.com/
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