User Manual

Table Of Contents
XBee®/XBeePRO®RFModules‐802.15.4‐v1.xEx[2011.06.1]
©2011DigiInternatonal,Inc. 23
Modes of Operation
XBee®/XBee-PRO® RF Modules operate in five modes.
Figure207. ModesofOperation
Idle Mode
When not receiving or transmitting data, the RF module is in Idle Mode. The module shifts into the
other modes of operation under the following conditions:
Transmit Mode (Serial data is received in the DI Buffer)
Receive Mode (Valid RF data is received through the antenna)
Sleep Mode (Sleep Mode condition is met)
Command Mode (Command Mode Sequence is issued)
Transmit/Receive Modes
RF Data Packets
Each transmitted data packet contains a Source Address and Destination Address field. The Source
Address matches the address of the transmitting module as specified by the MY (Source Address)
parameter (if MY >= 0xFFFE), the SH (Serial Number High) parameter or the SL (Serial Number
Low) parameter. The <Destination Address> field is created from the DH (Destination Address
High) and DL (Destination Address Low) parameter values. The Source Address and/or Destination
Address fields will either contain a 16-bit short or long 64-bit long address.
The RF data packet structure follows the 802.15.4 specification.
[Refer to the XBee/XBee-PRO Addressing section for more information]
Direct and Indirect Transmission
There are two methods to transmit data:
Direct Transmission - data is transmitted immediately to the Destination Address
Indirect Transmission - A packet is retained for a period of time and is only transmitted after
the destination module (Source Address = Destination Address) requests the data.
Indirect Transmissions can only occur on a Coordinator. Thus, if all nodes in a network are End
Devices, only Direct Transmissions will occur. Indirect Transmissions are useful to ensure packet
delivery to a sleeping node. The Coordinator currently is able to retain up to 2 indirect messages.