Operation
RFI-9256 Radio Modem User Manual
Page 29 of 109
The frame synchronisation is a TTL I/O on the DB25 connector described in Appendix A.3 on page 60.
Each RFI-9256 can be configured with one of the following synchronisation options:
No Sync Mode:
Disables synchronisation.
Output Sync Signal:
The radio will output a frame synchronisation signal. This is a falling edge on
the TTL output every time a new frame starts.
Follow Sync Signal:
The master radio will follow the synchronisation signal output by another unit.
This causes the master radio to adjust the start of its frame to match the falling edge detected on the
synchronisation TTL input. This mode should be used when a master is following another
collocated master.
Repeater Sync Mode:
The master radio will follow the synchronisation signal output by another
unit. This causes the master radio to adjust the start of its frame to be 50% offset from the falling
edge detected on the synchronisation TTL input. This mode should be used when a master is
following a collocated slave, such as when they are in back-to-back repeater configuration.
NOTE
: Synchronisation should not be used when directional bias has been enabled on either unit.
5.2.3 Network Configuration
A network of RFI-9256 radios will consist of one master, and one or more slaves. Multiple co-located
masters are supported in the RFI-9256 system through three mechanisms:
Hopping Pattern:
Each master unit has a unique hopping pattern. The hopping pattern determines
the order that the master hops over all available channels. There are 32 available hopping patterns,
and these have been selected so as to cause minimum interference between co-located masters. For
more information on configuring the hopping pattern, see section B.1.2 on page 72.
Network Address:
The network address is a number between 0 and 63 that defines the network to
which the master belongs. The network address provides a second layer of differentiation between
multiple masters. For more information on configuring the network address see section B.1 on page
69.
Security Code:
Each RFI-9256 can be programmed with a 32-bit security code. A slave will only be
able to communicate with a master if both units have the same security code. For more information
on configuring the security code see section B.5 on page 82.
The master and all the slaves in a single network must be configured with the same values for hopping
pattern, network address, and security code.
BACK-TO-BACK REPEATER OPERATION
The RFI-9256 supports network extension through the use of a back-to-back repeater. A back-to-back
repeater consists of two RFI-9256 radio radios. This is shown in Figure 11.
