Figure 2.3.1
2.4 RF Channel Access
The time a DNT24 network stays on each frequency in its hopping pattern is called the hop
duration
or
dwell
time, which
can be configured from 8 to 100 ms. Radio communication during each dwell is organized as a time division multiple ac-
cess (TDMA)
frame
. A DNT24 frame begins with a base-mode
beacon
, followed by 1 to 8 time
slots
used by the network
children to transmit to their parent, as shown in Figure 2.4.1. A base-mode beacon can include up to 8 messages ad-
dressed to one or more child radios. The number of slots is chosen accommodate the number of children that need to
send messages each hop.
Figure 2.4.1
Each beacon includes the status of all slots - either
registered
(assigned) or
open
. When a child radio has information to
transmit to its parent, it randomly selects one of the open slots and transmits all or the first part of its data. If the parent
successfully receives the transmission, it includes the child’s
MAC
address in the next beacon. This signals the child radio
that the slot is temporarily registered to it, allowing the child to efficiently stream any remaining data to the base hop-by-
hop until it is all sent.
©2009-2014 by Murata Electronics N.A., Inc.
DNT24 Integration Guide R2.0 - 10/27/14
www.murata.com
