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April 3, 2007
Is Wireless HART the Future?
April 3, 2007
There has been some news lately that the Wireless HART standard is gelling, and the world is beginning to see how it will be implemented. Rather than dwelling on the mechanics, I am wondering if this new transmission technique will stimulate users to use more HART enabled instruments in ways that take full advantage of all their capabilities. I ask the question because I don't understand why more users don't use HART functions now.
Wireless HART is being advanced as a new and easier way to unlock HART data, especially in legacy environments where operators don't want to put in additional cabling. In situations where a 4-20 mA signal is hard wired into a long serving DCS, the system can't handle the HART diagnostic information, so wireless offers a way to bring it into the system without needing new wires or disturbing the existing I/O setup. While all that is true and represents a perfectly logical argument, much of that capability is available today without wireless and yet users aren't taking advantage of it.For example, that same user in a legacy environment could simply go out and buy a loop interface and add it to the system to do the same things the new wireless device will. (Click here to read a recent article about this very topic.) If he or she adds it at the I/O connection, no additional cables will need to run to the instrument, nor will the connection to the instrument or DCS need to be disturbed. All can operate just as it was, and all the HART functions are available through the loop interface. This technology is nothing new, and yet 80+% of HART enabled instruments are not using the capabilities because users don't have provision to extract the data.Will wireless encourage users to do something they aren't doing now? The wireless devices are probably going to be more pricey than current loop interfaces (which aren't very expensive) so cost isn't the issue. The more complicated point is that a user has to have some way to interface and utilize the additional data with a control system. Whether the data comes in via wireless or loop interface, this requirement is the same. That is undoubtedly the more difficult issue, and the greater discouragement. Sadly, wireless is unlikely to help that. It is truly a wasted resource. Is there another side to this story that I'm missing?Posted by Peter Welander on April 3, 2007 | Comments (5)
Reader Comments
at 4/3/2007 1:59:33 PM, John Rezabek commented:
I worked for a large oil company that put HART AMS in 3 or 4 chemical plants, using HART muxes a la "Elcon" or their kin. Some plants had good success stories to tell (I believe one was "HART Plant of the Year"), but most saw little improvement. I think they kept doing what they always did, which didn''''''''''''''''t involve using all the HART capabilities. I suspect if you gave these plants the same info via wireless the result would be about the same. The legacy plants you refer to have some demographics worth contemplating. I know of few young engineers aching to work on instruments - I can think of maybe ONE we''''''''''''''''ve hired in the past 15 years. These same plants typically populate their instrument craft with operators senior enough to win a "bid" into a light-work day job. I would say the median age is 40-ish or higher. There''''''''''''''''s a lot of inertia to "keep doing what we always did".
at 4/13/2009 2:25:43 PM, Adam Kahn commented:
I guess the major question I have (and feel free to respond directly to my email account akahn@skodaminotti.com) is: what is the information extracted from HART devices used for? Does it hold the ability to increase operations that drive value? Does it limit risk? Can it increase efficiency? I have a basic level of understanding of how wireless HART can offer advantages from a systems perspective, but like your article addresses, what does the HART transfered information actually utilized for. From the prior comment, it seems like it can add value if implemented and utilized, but as he also articulates this seldom happens.
at 5/9/2009 9:28:02 AM, Sam commented:
These days the number of skilled Instrument technicians and engineers in process plants has been reduced to such a low level, that all of them are busy keeping the plants running, rather than going further out and analyzing data and such "long term" actions. Most are focused on keeping their jobs, not enhancing the quality of the automation or going beyond the call of duty. Secondly the reliability of transmitters has increased to such an extent that they continue to work for years without any need for troubleshooting. Most problems today are associated with the process interfaces, rather than the instruments themselves. So the failure of a measurement may be a plugged line, an incompatible process fluid, wrong process data, etc rather than an instrument which has developed a fault in its electronics. To that extent the HART diagnostics about the instrument itself may be rarely used. I could ramble on but then this is a comment and not a blog post!
at 5/21/2009 8:36:41 PM, Sergei Kuznetsov commented:
Yes, wireless field communications by may not change the unfortunate common attitude towards auxiliary diagnostic information available over digital field protocols. However I want to point out that Wireless HART (or ISA100, or other proprietary wireless technology) can also bring the primary measured variable to the control system. Of course, wired HART (or other digital protocols) could do it too, but the fact that it can now be done without a wire opens new opportunities to receive process data from locations where placing wired instruments is either too cumbersome or expensive. One beaten up example is a rotating kiln. Some applications may benefit from being able to move/add instruments without being burdened with the conduit installation costs. The driving force in these two examples would likely to be operations (likely to succeed in seeking additional process data that way), not maintenance department (see previous posts). Once the PV is in the system - wirelessly - the "extra" diagnoctics will be there as well, virtually free, and who knows - maybe more difficult to ignore.
at 6/19/2009 12:46:52 PM, Peter commented:
Add a Wireless Hart adapter to the instrument loop is less difficult, than add a Hart MPX for 16/32 channels? I do not think so. Use radio instead of wire connection is less complicated? I do not think so.
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