Emerson Process Management, using real data from a greenfield aromatics project, found that wireless could conservatively be applied to 44% of all measurement points. Similar to the JDI study, Smart Wireless showed significant savings of 36% in installation costs as compared with a hardwired, 4-20mA HART solution; Foundation fieldbus offered higher installation savings than WirelessHART, in part due to the current availability of higher density temperature measurement devices (four multiplexed sensors per transmitter with current wireless technology compared with eight for Foundation fieldbus).
The Foundation fieldbus design actually delivered the lowest installed-cost scenario relative to a 100% hard-wired approach. But many of the ongoing benefits of using wireless are not adequately accounted for in this analysis, the study noted. These include the ability to accommodate difficult or remote installations; simplified training and engineering; reduced need/cost for spare I/O capacity; ability to accommodate late changes and temporary installations; and the ease of adding future wireless points.
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