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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 (1)