Chip Lee from ISA mitigates the damage to the HART/SP100 relationship, and Wally Pratt speaks!

Making very clear that ISA is committed to working with the HART foundation, Chip Lee, who is in charge of standards at ISA among other things, introduced Wally Pratt, the chief engineer of the HART Communication Foundation. Pratt began by giving a history of the HART foundation, and described what it does, and how it does it. "We are an IEC approved international standard. WirelessHART is an integral part of that standard," Pratt said, correcting something both Wayne Manges and Pat Kinney had said, erroneously, this morning. "WirelessHART is an integral part of HART 7.o, which has just been approved." HART has about 42% market share of all instrumentation. "Since HART became an open standard," Pratt said, "we've sold about half as many devices as all the devices that there are in plants. We aren't going away anytime soon." You can see a really good multimedia version of an earlier incarnation of Wally's talk at http://www.controlglobal.com/articles/2007/184.html WirelessHART is an open, and interoperable standard. It is intended to be as easy as using wired HART. It is intended to enable wireless access to existing HART devices, using the same configuration, amintenance, diagnostic tools and procedures, and minimize the training requirements. Pratt talked about a major use case-- wireless connection to existing HART devices. Many installed DCS systems do NOT have digital HART signal inputs. This can be enabled by a wireless adaptor. We also wanted, he said, to allow for a new class of field devices that are battery, solar or field-powered devices. The HART 7 specifications have been approved by the membership with nearly unanimous ballot. There are new specifications for the physical layer, the data-link layer, network management, wireless commands, wireless devices, enhanced universal commands, 27 new common practice commands, and a WirelessHART User Manual. HART 7 is fully backward compatible with previous versions of HART. This is a multi-company development using standard HART practices. More than 25 companies were involved in the development, including aBB, Dust, Emerson, Honeywell, Siemens, Endress+Hauser, MACTek, Omnex, Pepperl+Fuchs, Yokogawa, and others. WirelessHART is a self organizing and self healing wireless mesh network. It is:
  • reliable
  • simple
  • flexible
  • preserves the HART user experience and command structure.
  • robust security using industry stanarrd AES-128 ciphers and keys
  • IEEE802.15.4 radio at 2.4 GHz--frequency hopping device.
"We're after the same kind of experience we had before." Pratt said it was a very simple, easy to deploy network. "But this doesn't mean that you shouldn't plan what you do ahead of time. You should plan your networking just as you plan your wired networking." " We have provided a total solution, with wireless field devices, wirelessHART adaptors, gateway.access poins, network manager and wireless hand held solutions.: "Security is an important part of what we did-- security is always on, with no option to turn it off." Finally, Pratt showed a benchmark against real world examples. It was a citric acid bio-reactor. "You set it up the same way you do a wired HART instrument. Let the network manager figure out the networking stuff." "We believe we've handled the coexistence issue, too. We expect to see a fairly high density of wirelessly networked security..." "And we believe that as people become more and more comfortable with WirelessHART, we expect to see control using WirelessHART." "Commissioning and diagnostics are just like wired HART." Pratt talked about WirelessHART adaptors. These devices are going to permit easy integration between WirelessHART and wired HART instruments. WirelessHART is integrated with EDDL. Troubleshooting a device that fails to join the network is frustrating, but using DDL and HART it becomes easy. Commissioning is very easy. YOu can start with a point to point topology, but as you add devices, you will start turning it into a mesh network. This gets around problems in the plant. WirelessHART complements and does not replace wired HART. Wireless is an enabling technology that opens the door to new opportunities for both users and suppliers in process automation. WirelessHART accomplishes these objectives while protecting installed investments. While there are no end users who are members of the HART Communication Foundation, ISA SP100 provided the same survey data to HART as they used for their own use cases. Control magazine hosted the study, and the information in the study will be revealed in the August issue.

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