WirelessHART Fieldgate SWG70, Operating Instructions Manual

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WirelessHART Fieldgate SWG70 3 Function and System Design
Hauser 9
3 Function and System Design
3.1 WirelessHART protocol
The HART protocol has until now used the wired 4–20mA loop with a superimposed digital signal
as physical layer. Although full digital communication is available in multidrop mode, the majority
of transmitters are connected to analog I/O cards and digital communication is used only for
parameterization, diagnosis and maintenance purposes.
WirelessHART now allows for the wireless transmission of HART data. To be employable
worldwide, WirelessHART utilizes the 2.4 GHz Band (IEEE 802.15.4 wireless network) as physical
layer. The WirelessHART devices form a mesh network in which every device is not just a
measurement point, but also a repeater. This results in a wider range for the whole network as well
as increased reliability through redundant communication paths.
The network may comprise three types of device:
• WirelessHART gateway (Fieldgate SWG70)
• WirelessHART field devices
• WirelessHART adapters (either connected to 4–20 mA/HART devices or acting as repeaters)
The WirelessHART network is built up, organized and maintained by the Fieldgate, which also takes
care for connection to different HOST systems through different bus interfaces.
Fig. 3-1: WirelessHART network
Host applications
Ethernet
WirelessHART
Fieldgate SWA70
Field devices with
Wireless Adapter SWA70