User's Manual

XTend™RFModule‐ProductManual
©2013DigiInternatonal,Inc. 12
Transparent Operation
By default, XTend RF Modules operate in Transparent Mode. The modules act as a serial line
replacement - all UART data received through the DI pin is queued up for RF transmission. When
RF data is received, the data is sent out the DO pin.
When the RO (Packetization Timeout) parameter threshold is satisfied, the module attempts to
initialize an RF transmission. If the module cannot immediately transmit (for instance, if it is
already receiving RF data), the serial data continues to be stored in the DI Buffer. Data is
packetized and sent at any RO timeout or when the maximum packet size is received.
The module operates as described above unless the Command Mode Sequence is detected. The
Command Mode Sequence consists of three copies of the command sequence character [CC
parameter] surrounded by the before and after guard times [BT & AT parameters].
If the DI buffer becomes full, hardware or software flow control must be implemented in order to
prevent overflow (loss of data between the host and module).
API Operation
API (Application Programming Interface) Operation is an alternative to the default Transparent
Operation. The API is frame-based and extends the level to which a host application can interact
with the networking capabilities of the module. When in API mode, all data entering and leaving
the RF module is contained in frames that define operations or events within the module.
Transmit Data Frames (received through the DI (Data In) pin) include:
• 16-bit address
Receive Data Frames (sent out the DO (Data Out) pin) include:
• Showing a received RF packet (16 bits only)
• Response to a TX (Transmit) packet
• Showing events such as hardware reset, watchdog reset, asynchronous events, etc.
The module will send data frames to the application containing status packets; as well as source,
RSSI and payload information from received data packets.
API operation option facilitates many operations such as the examples cited below:
To implement API operations, refer to ‘API Operation’ sections [p41].
DigiMesh Operation
XTend RF Modules containing firmware version 8020 (or above) now feature DigiMesh mesh
networking support. Mesh networking allows messages to be routed through several different
XTend nodes to a final destination node. This firmware load allows system integrators to bolster
their networks with the self-healing attributes of mesh networking. In the event that one RF
connection between nodes is lost (due to power-loss, environmental obstructions, etc.) critical
data can still reach its destination due to mesh networking capabilities embedded inside the
module. Transparent or API operations can be used in conjunction with the mesh networking
topology. A separate product manual exists for DigiMesh modules. This product manual can be
found on the Digi support site.
-> Change destination addresses without having to enter command mode
-> Receive success/failure status of each RF packet
-> Identify the source address of each received packet