User's Manual

FreeWave Technologies Spread Spectrum Transceiver User Manual
900 MHz and 2.4 GHz
V5.0S
37
(5) RF Xmit Power
(6) Slave Security
With option 6 the user may disable the transceiver’s security so it will accept a call
from any other FreeWave unit. The default setting is 0 where security is enforced
(the caller’s serial number must be in the slave’s Call Book), with a setting of 1
security is disabled.
As mentioned in mode 6, Slave Security must be set to one when the unit is
operating in a point-to-point system where it may need to accept calls from more
than 10 different FreeWave Transceivers. However, it is important to note that
when Slave Security is set to 1 the Transceiver will accept calls from any other
FreeWave Transceiver, and additional system security measures should be taken
to prevent unauthorized access.
(7) RTS to CTS
Menu selection 7 in the Radio Parameters provides the option of allowing the RTS
line (pin 7) on the Master modem to control the CTS line (pin 8) of the Slave. This
pass-through control can be enabled in point-to-point mode as well as point-to-
multipoint. In the latter the Master RTS line will control all Slaves’ CTS lines.
When this mode is enabled the CTS line ceases to function as flow control.
Therefore it is not recommended to enable this feature when operating at RS-232
speeds above 38.4 kB.
To enable this mode, enter 7 in the Radio Parameters menu. An entry of 1 will
enable the RTS-CTS control, 0 will disable it.
Just before the time the Master is scheduled to transmit a packet, it will sense the
state of the RTS line. If the state has changed, the Master will then transmit a
message to the Slave with the new status. This transmission will occur regardless
of data to be sent or not. In the former case the RTS status message will be sent
in addition to the data. In point-to-point mode the Master will continue sending the
new status message until it receives an acknowledgment from the Slave. In point-
to-multipoint mode the Master will repeat the message the number of times equal
to the Master Packet Repeat number in the Multipoint Setup menu.
Because the Master transmit time is completely asynchronous to the occurrence of
any change of the RTS line, the latency time from RTS to CTS is variable. The
maximum time, however, is determined by the frequency of Master transmission
times. This frequency is determined by the Maximum Packet Size and Minimum
Packet Size parameters in the Radio Parameter menu. Setting both parameters to
their maximum of 9 and 9 will produce a maximum latency time of approximately
21 ms. At their minimum numbers the time will be approximately 5.9 ms. Please
note that this latency can go up significantly if packets are lost between the Master
and Slave. In point-to-multipoint mode there is no absolute guarantee that the
state change will be communicated to all Slaves in the unlikely event that all
repeated packets from the master do not get through to all Slaves.
Note: The RTS to CTS mode does not function in point to point links which
contain a repeater. If this feature is needed in a link with a repeater you
should use it in conjuction with point to multipoint mode.