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SD Series Technical Manual
MDS 05-4846A01, Rev. H
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Figure 30. Store and Forward System Example
Store and Forward is available in Packet w/MAC mode and supports all
MAC features including collision avoidance, retries, and acknowledge-
ments. Furthermore, all major radio features are supported in SAF net-
works such as diagnostics, over the air programming, bridging, VRCs,
etc.
Dual Duty of SAF Remotes:
Since a SAF device doubles as a Remote
radio it may participate in direct exchanges with the Master/AP. By
design, an SAF device is always within the primary coverage area and
has direct communication to the Master/AP. Therefore, all SAF devices
act as both a standard Remote for direct exchanges, as well as an SAF
unit for Store and Forward exchanges. A SAF exchange is defined as
any exchange between the Master/AP and a Remote through an SAF
device. In all cases, the Master/AP still controls the operation of the net-
work.
After sending a SAF data frame, the Master/AP remains idle until the
frame has been delivered to the Remote, at which time it will return to
direct or SAF operation, depending on the message type (unicast or
broadcast).
Direct vs. SAF Traffic:
Depending on network topology, it is possible
for some Remotes to hear both direct polls from the Master/AP and SAF
messages from an SAF-designated Remote. It is more desirable to use
the direct traffic to avoid the latency of going through the SAF link, and
the radio’s firmware handles this situation automatically. SAF frames
are ignored when the direct path is available. The system is dynamic; if
the direct path becomes unavailable for any reason, it quickly switches
to the SAF path to provide continued operation.
