Tuesday, November 9, 2010

The Wide World of Wireless

We had a full house last week here in Charlotte, as we played host to a large group from the Savannah River Site. The focus of the three days was Wireless HART (WiHART) networks, and we had extensive, hands-on sessions.

Security was a primary focus, both to make sure the WiHART networks didn’t interfere with other RF domains and to make sure the WiHART network was secure from outside interference, both accidental and intentional.

We set up 20 different wireless instruments throughout our campus, both indoors and out, on three separate wireless gateways connected to DeltaV. Larry Wolfe, Director of Technology Deployment, and Carl Price, Director of PlantWeb Services, developed a variety of deployment scenarios to test such things as long distances (in excess of 500 ft) and signal paths through solid and glass doors.

Jeff Potter, Rosemount’s wireless security expert provided a detailed overview of the many features incorporated into Emerson’s WiHART technology specifically designed to keep it safe. One thing I learned was the way the gateway and instrument change up their encryption. See, if you had an instrument that was reading the same value all the time or one that changes very slowly (think outside air temperature), the signal back to the gateway, while encrypted, would be the same. Not so with the smarts built into WiHART. By modulating the encryption, eavesdropping or snooping become problematic.

Another clever security feature is the ability to use a HART modem attached to AMS to automatically setup the join keys on the wireless devices. This way, knowledge of the join key is limited, and only instruments that get temporally connected before being deployed to the field can join the appropriate gateway.

Our guests came well prepared also, bringing a couple of guys in from Oak Ridge with all sorts of RF sniffing tools. They were specifically looking at our 4 wireless office networks and how the WiHART devices were showing up in the RF world.

After the 3 days, the visit was considered a success.  Emerson’s WiHART passed the test and with apologies to UPS, Rosemount and RE Mason can ask “what can Blue do for you”?