NI 9792 WSN Real-Time Gateway User Guide and Specifications
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End Node Versus Router
Each NI WSN-32
xx
node can be configured as either an end node or a router. NI WSN-32
xx
nodes are
configured by default at the factory in end node mode. You can change the mode of the node using the
NI-WSN software and NI MAX. One trade-off to consider when configuring nodes is power
consumption. NI WSN-32
xx
nodes configured as end node are designed to be run from battery power
while routers are designed to use external power at all times to send, receive, and buffer messages to and
from end nodes.
Data Transfer in the NI WSN Network
The NI WSN system is built on a low-power, reliable IEEE 802.15.4 network. In order to save power
and increase reliability, this network delivers a maximum theoretical throughput of 250 kbps. This
correlates to a typical maximum rate of 1 sample per second per node.
Measurements taken with NI WSN-32
xx
nodes are single point acquisition. NI WSN-32
xx
devices have
no onboard buffer, therefore the data is considered to be lost, meaning there is no way to retrieve past
data from the device.
Configuring Your NI WSN System
As discussed in the
section, creating a reliable and efficient wireless sensor network
requires an understanding of the physical environment of the network, as well as an understanding of
the expected meshing configuration. For example, parent devices (routers and gateways) can only have
a maximum of eight end nodes connected to them at a given time.
This maximum number introduces the stranded node problem. The stranded node problem exists when
a node, configured as an end node, ends up not being able to join a network. Figure 18 shows a network
consisting of one gateway, two routers, and nine end nodes.
