On the Implementation and Performance Assessment of a WirelessHART Distributed Packet Analyzer

Wireless sensor networks are nowadays a reality. The wide consensus gained by the IEEE 802.15.4 standard has facilitated the adoption of wireless links not only in the consumer world but also as a valid replacement of traditional wired industrial networks. In particular, the physical layer specs of IEEE 802.15.4 comply with the critical requirements of industrial applications as low cost and low power. The most remarkable example of this strategy is WirelessHART (WH), which is the first wireless fieldbus based on an open standard and specifically designed for process measurement and control applications. It uses traditional IEEE 802.15.4 radios but adopts a synchronized time-division medium-access strategy and relies on HART protocol for the upper layers. Its mesh topology allows for efficient and reliable coverage of large areas. It was presented in September 2007, but test specifications have officially been released just a few months ago, together with the announcement of the "Wireless Test System", which is only available to HART consortium members. In this paper, the authors deeply discuss the design and performance of a new and innovative packet analyzer purposely designed for the WH protocol. To the authors' knowledge, it is the first instrument that pursues a distributed approach so that it can be used both for laboratory tests and for on-the-field measurements during the plant commissioning. It is capable to simultaneously scan all available RF channels and to furnish packet timestamping with accuracy on the order of microsecond, as verified by an extensive measurement campaign. In addition, a dissector for the well-known WireShark software has also been implemented and described, providing a very simple and intuitive analysis. Moreover, the proposed instrument has been interfaced with a preliminary version of the analysis software supplied by the HART consortium.