User Manual

Operation
RFI-9256 Radio Modem User Manual Page 27 of 96
All protocol modes support back-to-back repeaters for extending network coverage.
4.3.1 Point-to-point Protocol
A point-to-point network establishes a link between two radio radios, through an optional number of
repeaters. A point-to-point connection can be established on the main, auxiliary, or both serial ports.
A single master unit and a single slave unit are configured such that:
 The have the same hopping pattern, network address, and security code.
 The master and slave have different local addresses.
 Both the master and slave have the point-to-point protocol selected on their main serial port.
 The point-to-point destination address on the slave is set to the master’s local address, while the
point-to-point destination address on the master is set to the slave’s local address.
This results in a connection being established between the two units. The online LED should turn green on
both units, and data transmitted by the DTE on the master be received on the DTE on the slave, and vice
versa.
4.3.2 Broadcast Protocol
In a point-to-multipoint broadcast network, data transmitted by the master unit is output by all the slaves,
while data transmitted by each slave is only output by the master.
When using point-to-multipoint broadcast mode, there are no acknowledgments on the master to slave
transactions. This is because multiple slaves may be receiving the data, and if they were to all attempt to
acknowledge the transmission they would interfere with each other.
Instead of acknowledgements, the master will transmit each message a fixed number of times equal to the
maximum retries. For this reason, the number of retries used in a broadcast network should be configured to
between 1 and 5 in order to maintain a reasonable throughput.
4.3.3 Hayes Dial-up Protocol
Hayes dial-up networks provide connection mechanism that emulates a PSTN modem’s dialling mechanism.
This is a more powerful method of operating than using point-to-point or point-to-multipoint broadcast
networks, as it allows dedicated communication between a master and one of many slaves.
CONNECTION MANAGEMENT
DIALLING
The AT commands may be used to initiate dialling of a remote radio. The ATD command is use to establish a
connection. The form of the ATD command is:
ATD<address><extension>