Linx Technologies TRM-915-R250 - Manual (Page 10)

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GUID Networking Mode
GUID networking mode is the simplest mode and supports point-to-point
and broadcast communications. Each module is programmed at
the factory with a unique 4-byte ID number that cannot be changed.
These bytes are found in the non-volatile read only MYGUID registers
(regMYGUID[0-3]). GUID networking mode uses these IDs as addresses.
The transmitting unit’s GUID is used as the source address and the
intended receiver’s GUID is written into the destination address register
(regDESTGUID[0-3]). All modules within range hear the transmission, but
only the module with the ID that matches the destination address outputs
the data on its UART. All others ignore the transmission.
A broadcast message is created when the destination address is
0xFFFFFFFF. In this case, all modules within range output the data. It is not
recommended to send broadcast messages when acknowledgements are
enabled. Figure 11 lists some examples of how GUID networking works.
Networking Modes
The module has a very flexible addressing and networking scheme selected
with the regNVNETWORKMODE and regNETWORKMODE registers. It
can be changed during operation. The transmitting module addresses
packets according to the network mode configuration. The receiving
module processes all addressing types regardless of the network mode
configuration. If the received message matches the addressing criteria, it is
output on the UART. Otherwise it is discarded.
There are three networking modes: GUID, User and Extended User. Each
mode offers different communications schemes, but all use source and
destination addressing. The source address is for the transmitting unit,
the destination address is the intended receiver. Each mode uses different
registers for the source and destination addresses.
The module supports an automatic addressing mode that reads the
Source Address from a received packet and uses it to fill the Destination
Address register. This makes sure that a response is sent to the device that
transmitted the original message. This also allows the host microcontroller
to read out the address of the sending unit.
The automatic addressing is enabled for the different networking modes
with register regAUTADD and regNVAUTADD.
250 Series Transceiver GUID Network Mode Examples
Sender Receiver
Network
Mode
MyGUID
Destination
GUID
MyGUID Response
0x04
(GUID)
0x00001000 0xFFFFFFFF
0x00002000 Data output by both modules.
No RF ACK sent by either
module. 0x00003000
0x14
(GUID +
ACK)
0x00001000 0xFFFFFFFF
0x00002000 Data output by both modules.
No ACK sent by either module.
This configuration causes
transmission problems.
0x00003000
0x14
(GUID +
ACK)
0x00001000 0x00003000
0x00002000 Not processed – discarded.
0x00003000 Data output. RF ACK sent to
0x00001000
0x04
(GUID)
0x00001000 0x00002000
0x00002000 Data output. No RF ACK sent.
0x00003000 Not processed – discarded.
Figure 11: 250 Series Transceiver GUID Network Mode Examples