User's Manual
Table Of Contents
- 1. XTend RF Module
- 2. RF Module Operation
- 3. RF Module Configuration
- Programming Examples
- Command Reference Table
- Command Descriptions
- %V (Board Voltage) Command
- AM (Auto-set MY) Command
- AP (API Enable) Command
- AT (Guard Time After) Command
- BD (Interface Data Rate) Command
- BR (RF Data Rate) Command
- BT (Guard Time Before) Command
- CC (Command Sequence Character) Command
- CD (GPO2 Configuration) Command
- CF (Number Base) Command
- CN (Exit AT Command Mode) Command
- CS (GPO1 Configuration) Command
- CT (Command Mode Timeout) Command
- DB (Received Signal Strength) Command
- DT (Destination Address) Command
- E0 (Echo Off) Command
- E1 (Echo On) Command
- ER (Receive Error Count) Command
- FH (Force Wake-up Initializer) Command
- FL (Software Flow Control) Command
- FS (Forced Synch Time) Command
- FT (Flow Control Threshold) Command
- GD (Receive Good Count) Command
- HP (Hopping Channel) Command
- HT (Time before Wake-up Initializer) Command
- HV (Hardware Version) Command
- ID (Modem VID) Command
- KY (AES Encryption Key) Command
- LH (Wake-up Initializer Timer) Command
- MD (RF Mode) Command
- MK (Address Mask) Command
- MT (Multi-transmit) Command
- MY (Source Address) Command
- NB (Parity) Command
- PB (Polling Begin Address) Command
- PD (Minimum Polling Delay) Command
- PE (Polling End Address) Command
- PK (Maximum RF Packet Size) Command
- PL (TX Power Level) Command
- PW (Pin Wake-up) Command
- RB (Packetization Threshold) Command
- RC (Ambient Power - Single Channel) Command
- RE (Restore Defaults) Command
- RM (Ambient Power - All Channels) Command
- RN (Delay Slots) Command
- RO (Packetization Timeout) Command
- RP (RSSI PWM Timer) Command
- RR (Retries) Command
- RT (GPI1 Configuration) Command
- SB (Stop Bits) Command
- SH (Serial Number High) Command
- SL (Serial Number Low) Command
- SM (Sleep Mode) Command
- ST (Time before Sleep) Command
- TP (Board Temperature) Command
- TR (Transmit Error Count) Command
- TT (Streaming Limit) Command
- TX (Transmit Only) Command
- VL (Firmware Version - Verbose)
- VR (Firmware Version - Short) Command
- WA (Active Warning Numbers) Command
- WN (Warning Data) Command
- WR (Write) Command
- WS (Sticky Warning Numbers) Command
- API Operation
- 4. RF Communication Modes
- Appendix A: Agency Certifications
- Appendix B: Development Guide
- Appendix C: Additional Information
XTend™RFModule‐ProductManual
©2013DigiInternatonal,Inc. 47
Multi-transmit Mode
Attributes:Reliable Delivery through forced transmission of every RF packet
Every RF packet is sent exactly (MT + 1) times with no delays between packets
Diminished throughput and increased latency
Required Parameter Values (TX module): MT (Multi-Transmit) >= 1
Other Related Commands: Networking (DT, MK, MY, RN, TT), Serial Interfacing (BR, PK, RB,
RO), RF Interfacing (FS)
Recommended Use: Use for applications that require Reliable Delivery without using retries and
acknowledgements.
Connection Sequence
Figure4‐05. Multi‐TransmitModeStateDiagram
(TXModule)
In Multi-Transmit Mode, each packet is
retransmitted MT times, for a total of (MT+1)
transmissions. There is no delay between
retransmissions, and the TX (transmitting)
module will never receive RF data between
retransmissions. Each retransmission includes
an RF initializer. A transmission event may
include follow-on packets, each of which will be
retransmitted MT times. The Forced Sync (FS)
parameter is ignored in Multi-Transmit Mode.
The RB and RO parameters are not applied to
follow-on packets, meaning that once
transmission has begun, it will continue
uninterrupted until the DI buffer is empty or
the streaming limit (TT parameter) has been
reached. As with the first packet, the payload
of each follow-on packet includes up to the
maximum packet size (PK parameter) bytes,
and the TX module checks for more pending
data near the end of each packet. Follow-on
packets are not sent until all retransmissions of
the previous packet are finished.
The streaming limit (TT) is specified at the TX
module as the maximum number of bytes that
the TX module can send in one transmission
event, which may consist of many packets. If
the TT parameter is reached, the TX module
will force a random delay of 1 to RN delay slots
(exactly 1 delay slot if RN is zero). In Multi-
Transmit Mode, each packet is counted only
once when tracking the streaming limit (TT),
no matter how many times it is retransmitted.
When an RX (receiving) module receives a
Multi-Transmit packet, it calculates the amount
of time remaining in the Multi-Transmit event,
and inhibits its own transmissions for the
duration of the Multi-Transmit event, plus a
random number of delay slots between 0 and (RN-1). If the local RN parameter is zero, the delay
is only for the calculated duration of the Multi-Transmit event. Thus, an RX module need only
receive one of the transmissions, and it will keep off the channel until the TX module is done. If
follow-on packets are coming, the RX modules will move to the new frequency and listen for the
follow-on packet for a specific period of time.