User's Manual

XTend™RFModule‐ProductManual
©2013DigiInternatonal,Inc. 13
Modes of Operation
XTend RF Modules operate in six modes.
Figure2‐04. XTendRFModuleModesofOperation
(RFmodulescanonlybeinonemodeatatime)
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
• Shutdown Mode: Shutdown condition is met
• Sleep Mode: Sleep Mode condition is met
• Command Mode: Command Mode Sequence is issued
The module automatically transitions back to Idle Mode after responding to these conditions.
Transmit Mode
When the first byte of serial data is received from the UART in the DI buffer, the module attempts
to shift to Transmit Mode and initiate an RF connection with other modules. After transmission is
complete, the module returns to Idle Mode.
RF transmission begins after either of the following criteria is met:
Figure2‐05. TransmitModeDataFlow
The character timeout trigger can be
disabled by setting RO to zero. In this
case, transmission will not begin until
RB bytes have been received and are
pending for RF transmission. The RB
parameter may be set to any value
between 1 and the RF packet size [refer
to PK (Max RF Packet Size) parameter],
inclusive. Note that transition to
Transmit Mode cannot take place during
RF reception; the RF reception must
complete before the radio can transition
into Transmit Mode.
If RB or RO conditions are met, the
module initializes a communications channel. Serial data in the DI buffer is grouped into RF
packets (up to 2048 bytes in each packet, refer to PK Command), converted to RF data and is
transmitted over-the-air until the DI buffer is empty.
1. RB bytes have been received by the UART and are pending for RF transmission.
[Refer to the RB (Packetization Threshold) Command]
2. At least one character has been received by the UART and is pending for RF transmission;
and RO character times of silence been observed on the UART.
[Refer to the RO (Packetization Timeout) Command]