The protocols are intended for use in communicating with
field instruments and fulfil a similar purpose to that of H1
fieldbusses. Although the terminology used to describe specific
components differs from standard to standard, all of the
standards are defined to cater for a similar set of devices.
These are security and network management devices, gateway
devices, routing devices, non-routing devices and handheld
devices. The various instruments connect in a self-organising
hybrid star/mesh network, which is controlled by the network
and security management devices. The management
devices are powerful, wired devices, which interface to the
wireless portion of the network through the gateway device.
The gateway device can also be implemented as a protocol
converter, making use of a wired fieldbus protocol to facilitate
deterministic communication between the gateway and any
controllers [39]. The mesh portion of the network is realised by
the routing devices, which in turn connect nearby non-routing
devices through the star portion of the network