An improved multipurpose pipe coupling for use down to 2 K

Abstract

Apart from ZigBee, there are other standards that adopt the IEEE 802.15.4 PHY and MAC layers to offer a wireless networking protocol. This chapter provides an overview of two such standards (6LoWPAN and Wireless HART) that reuse the IEEE 802.15.4 PHY and MAC layers as part of their wireless networking protocol. The 6LoWPAN standard is developed specifically for the nodes that have limited memory space and processing capabilities. The IPv6 requires support of packet sizes much larger than the largest IEEE 802.15.4 packet size. The IPv6 packets need to be fragmented by the transmitter and reassembled by the receiver to accommodate the requirements of both standards. The adaptation layer in 6LoWPAN is responsible for fragmenting and reassembling the packets. One of the advantages of this is that a 6LoWPAN node is capable of communicating with other IP-enabled devices. Furthermore, Highway Addressable Remote Transducer (HART) is a communications protocol for applications such as process control, equipment and process monitoring, advanced diagnostics, and closed loop control in wired industrial networks. WirelessHART is a wireless networking standard based on HART that adds wireless flexibility to an existing HART network. WirelessHART operates at the 2.4 GHz ISM band and is backward compatible with existing HART devices, commands, and tools. WirelessHART supports mesh networking. Both ZigBee and WirelessHART can be used in industrial monitoring and control applications. If a wired HART network is present, WirelessHART can be a better choice than ZigBee because of backward compatibility with the HART network.