Reference Manual

Network Design Best Practices
March 2016
Reference Manual
00809-0100-4045, Rev AB
59
Network Design Best Practices
Appendix D Network Design Best
Practices
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 59
Effective range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 59
D.1 Overview
All recommended practices should be followed to ensure highest data reliability. Deviation
from these best practices may require device repeaters in the network to maintain 99% data
reliability. The following are guidelines to achieve the best possible wireless network.
 Each wireless network field should be scoped to a single process unit.
 Minimize the number of hops to the Gateway in order to reduce latency. A
minimum of five wireless instruments should be within effective range of the
Emerson
™
Smart Wireless Gateway.
 Each device in the network should have at minimum three devices with potential
communication paths. A mesh network gets its reliability from multiple
communication pathways. Ensuring each device has multiple neighbors within
range will result in the most reliable network.
 Have 25 percent of wireless instruments in the network within range of Emerson
Wireless Gateway. Other enhancing modifications include creating a higher
percentage of devices within effective range of the gateway to 35 percent or more.
This clusters more devices around the gateway and ensures fewer hops and more
bandwidth available to WirelessHART
®
devices with fast scan rates.
 Effective range is determined by type of process unit and the density of the
infrastructure that surrounds the network.
D.2 Effective range
Heavy Obstruction: 100 ft. (30 m). Typical heavy density plant environment. Cannot drive a
truck or equipment through.
Medium Obstruction: 250 ft. (76 m). Typical light process areas, lots of space between
equipment and infrastructure.
Light Obstruction: 500 ft. (152 m). Typical of tank farms. Despite tanks being big
obstructions themselves, lots of space between and above makes for good RF propagation.
Line of Sight: 750 ft. (230 m). No obstructions between WirelessHART devices and devices
mounted a minimum of 6 ft. (2 m) above ground or obstructions.
For examples and complete explanations, refer to the IEC62591 WirelessHART System
Engineering Guide
.