User's Manual

FreeWave Technologies Spread Spectrum Transceiver User Manual

900 MHz and 2.4 GHz

V5.0S

(8) Retry Time Out

The Retry Time Out parameter allows the user to determine when a slave will drop

a connection to a master or repeater in multipoint mode. The default setting is

255, meaning that if one packet in 255 from the master is sent successfully to the

slave it will maintain a link. The lowest setting is 8, at which a slave will drop a

connection much more quickly.

The Retry Time Out parameter is useful when a multipoint system is used with a

moving master or slaves. As the link gets weaker, a lower setting will allow a

transceiver to drop a link and search for a stronger connection.

While intended primarily for multipoint systems, the Retry Time Out parameter

may also be modified in point to point systems. In point to point mode the Retry

Time Out should not be set to a value of less than 151.

(9) Lowpower Mode

The Lowpower Mode is an option that, when enabled, allows the transceiver to

function as a multipoint slave while consuming less power.

With a setting of 1 Lowpower Mode saves current consumption primarily by

dimming the transceiver's LEDs. When set to higher values (2 through 63) the

transceiver will sleep between slots. For example, at a setting of 2 the transceiver

sleeps 1 out of 2 slots, at a setting of 3 the transceiver sleeps 2 out of 3 slots, and

so on.

Note: 1) The Lowpower Mode is for use only in point to multipoint systems, and

only on the multipoint slaves. The power savings occur when the option is

enabled and the slave is connected to the master or a repeater. There are

no power consumption savings when the slave is transmitting data back to

the master. Designed primarily for SCADA systems, the Lowpower Mode

is of little value when significant amounts of data need to be sent from the

slave to the master.

2) Additional power savings may be realized when the number of

repeaters is set to 1 throughout the network, even if no repeaters are

being used. This is shown in the following table in the Draw1 column, the

Draw0 column shows power draw with a setting of 0 repeaters.

3) Because the Lowpower mode puts the transceiver to sleep a latency

will be introduced before it become fully linked to the master. This latency

can range from 6 ms to 2.5 seconds.

4) To communicate to the RS232 port of a transceiver that is in Lowpower

Mode the RTS line must be held high to wake it up. The transceiver will

wake up within approximately 20 milliseconds or when CTS goes high.

5) If the RTS line on the slave is held high the transceiver will remain in

normal operation regardless of the Lowpower Mode setting. Once RTS is

dropped it will go back into the lowpower mode that corresponds to its

setting.

The following table shows how the power consumption is reduced at different

Lowpower Mode settings. The actual current draw depends an many factors, so