User's Manual

Table Of Contents
XBee®/XBeePRO®ZBRFModules
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Applications that require multiple data collectors can also use many-to-one routing. If more than
one data collector device sends a many-to-one broadcast, devices will create one reverse routing
table entry for each collector.
In ZB firmware, the AR command is used to enable many-to-one broadcasting on a device. The AR
command sets a time interval (measured in 10 second units) for sending the many to one
broadcast transmission. (See the command table for details.)
Source Routing
In applications where a device must transmit data to many remotes, AODV routing would require
performing one route discovery for each destination device to establish a route. If there are more
destination devices than there are routing table entries, established AODV routes would be
overwritten with new routes, causing route discoveries to occur more regularly. This could result in
larger packet delays and poor network performance.
ZigBee source routing helps solve these problems. In contrast to many-to-one routing that
establishes routing paths from many devices to one data collector, source routing allows the
collector to store and specify routes for many remotes.
To use source routing, a device must use the API firmware, and it must send periodic many-to-one
route request broadcasts (AR command) to create a many-to-one route to it on all devices. When
remote devices send RF data using a many-to-one route, they first send a route record
transmission. The route record transmission is unicast along the many-to-one route until it
reaches the data collector. As the route record traverses the many-to-one route, it appends the
16-bit address of each device in the route into the RF payload. When the route record reaches the
data collector, it contains the address of the sender, and the 16-bit address of each hop in the
route. The data collector can store the routing information and retrieve it later to send a source
routed packet to the remote. This is shown in the images below.