Operation
Maximum payload
XBee/XBee-PRO S2C 802.15.4 RF Module User Guide
41
Maximum payload summary tables
The following table indicates the maximum payload when using transmit compatibility with the Legacy
802.15.4 module (S1 hardware).
Encryption
Enabled
Disabled
95 B
100 B
The following table indicates the maximum payload when using the application header and not using
encryption. Increment the maximum payload in 2 bytes if you are not using the application header.
Destination Address
Source Address Short
Long
Short
114 B
108 B
Long
108 B
102 B
The following table indicates the maximum payload when using the application header and using
encryption. Increment the maximum payload in 4 bytes if you are not using the application header.
Destination Address
Source Address Short
Long
Short
101 B
95 B
Long
101 B
95 B
Work with Legacy devices
The Legacy 802.15.4 module (S1 hardware) transmits packets one by one. It does not transmit a
packet until it receives all expected acknowledgments of the previous packet or the timeout expires.
The new XBee/XBee-PRO S2C 802.15.4 RF Modules enhance transmission by implementing a
transmission queue that allows the device to transmit to several devices at the same time. Broadcast
transmissions are performed in parallel with the unicast transmissions.
This enhancement in the XBee/XBee-PRO S2C 802.15.4 RF Module can produce problematic
behavior under certain conditions if the receiver is a Legacy 802.15.4 module (S1 hardware).
The conditions are:
n
The sender is a XBee/XBee-PRO S2C 802.15.4 RF Module, and the receiver is a Legacy 802.15.4
module.
n
The sender has the Digi Header enabled (
MM
= 0 or 3) and
RR
(XBee Retries) > 0.
n
The sender sends broadcast and unicast messages at the same time to the Legacy 802.15.4
module without waiting for the transmission status of the previous packet.
The effect is: