Operation
Networking
n
The receiver may display duplicate packets.
The solution is:
n
Set bit 0 of the C8 (802.15.4 Compatibility) parameter to 1 to enable TX compatibility mode in the
XBee/XBee-PRO S2C 802.15.4 RF Module. This eliminates the transmission queue to avoid sending
to multiple addresses simultaneously. It also limits the packet size to the levels of the Legacy
802.15.4 module.
Networking
The following table describes some common terms we use when discussing networks.
Term
Definition
Association
Coordinator
End device
Establishing membership between end devices and a coordinator.
A full-function device (FFD) that provides network synchronization by polling nodes.
When in the same network as a coordinator. Devices that rely on a coordinator for
synchronization and can be put into states of sleep for low-power applications.
PAN
Personal Area Network. A data communication network that includes one or more
end devices and optionally a coordinator.
MAC Mode configuration
Medium Access Control (MAC) Mode configures two functions:
1. Enables or disables the use of a Digi header in the 802.15.4 RF packet.
When the Digi header is enabled (MM = 0 or 3), duplicate packet detection is enabled as well as
certain AT commands.
Modes 1 and 2 do not include a Digi header, which disables many features of the device. All
data is strictly pass through.
2. Enables or disables MAC acknowledgment request for unicast packets.
When MAC ACK is enabled (MM = 0 or 2), transmitting devices send packets with an ACK
request so receiving devices send an ACK back (acknowledgment of RF packet reception) to the
transmitter. If the transmitting device does not receive the ACK, it re-sends the packet up to
three times or until the ACK is received.
Modes 1 and 3 disable MAC acknowledgment. Transmitting devices send packets without an
ACK request so receiving devices do not send an ACK back to the transmitter.
Broadcast messages are always sent with the MAC ACK request disabled.
The following table summarizes the functionality.
Mode
Digi Header MAC ACK
0 (default) V
V
1
2
V
3
V
XBee/XBee-PRO S2C 802.15.4 RF Module User Guide
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ETC [ ETC ]
