Rockwell Automation 1425 PowerMonitor Wireless 250 - Manual (Page 17)

Rockwell Automation Publication 1425-UM001A-EN-P - January 2012 17
Hardware Installation Chapter 2
Effect of Different Materials on Signal Strength and Maximum Node-to-node Distance
Glass, sheet rock, and wood have the least impact to the RF signal.
Steel-reinforced concrete, brick walls, and corrugated steel surfaces are much
more difficult for the RF signal to penetrate. The maximum node-to-node
distance could be cut in half compared to the unobstructed maximum distance.
In any case, the maximum distance between two nodes depends on the geometry
of the signal path and the number, thickness, and composition of any
obstructions.
Metal blocks virtually all radio communication. RF transmission through metal
is facilitated by openings (slits, holes, and gaps) in the metal.
Network Topologies
The robustness and reliability of communication between PowerMonitor W250
devices and RSEnergyMetrix software or other clients depends primarily on
network RF signal strength. In turn, RF signal strength is dependent upon the
topology of the network. In general, a mesh network topology that provides
parallel links between devices provides better RF signal strength resulting in
more robust communication. Linear topologies that offer only a single path from
device to client can create bottlenecks that reduce effective RF signal strength
and adversely impact communication robustness. You may add more routers to a
network topology to accommodate longer distances or add parallel routes
through the network in areas that present a challenging environment.
Preferred Network Topology
An ideal network topology is ‘Star-Mesh’, where all nodes are evenly distributed
from the PC Receiver and offer multiple, parallel communication links.
In such a configuration, all devices can communicate with multiple nodes, so that
if one router fails or if a radio link experiences interference, the network will
reconfigure itself through the remaining nodes. Having multiple routes to the
gateway will also improve the estimated sampling rate.