User's Manual

Spread Spectrum Wireless Data Transceiver User Manual
Preliminary GXM Manual Version 0.2 31
PRELIMINARY
(3) XMIT RATE
Two settings for the Transmit Rate parameter are available. The setting for normal operation of the
transceiver is a Transmit Rate 1. Transmit Rate 0 is useful to qualitatively gauge signal strength in Point
to Point mode. When set to Transmit Rate 0, the transceivers will transmit back and forth continuously,
even if no data is being applied to the serial port. A Transmit Rate setting of 0 should be used only as a
diagnostic tool and not for normal operation. The strength of the signal may be gauged by the Clear to
Send (CTS) LED. A solid red CTS LED indicates a strong signal; a blinking CTS LED indicates a weaker
signal.
(4)
RF DATA RATE
FreeWave transceivers have two settings for the RF Data Rate (2, 3). RF Data Rate should not be
confused with the serial port Baud Rate. Setting 2 (RF Speed of 153.6kbps) should be used when the
transceivers are close together and data throughput needs to be optimized. Setting 3 (RF Speed of
115.2kbps) should be used when the transceivers are farther away and a solid data link is preferred over
data throughput.
Note: In MultiPoint networks, the RF Data Rate must be set identically in all transceivers. Any
transceiver with an RF Data Rate different from the Master will not establish a link.
In Point to Point networks the Master’s settings take precedence over the Slave.
(5) RF XMIT POWER
The maximum output power of 500 mW is achieved by setting the RF Xmit Power setting to 10.
(6)
SLAVE SECURITY
Slave security is a feature that allows Slave transceivers to accept transmissions from a Master not
included in the Call Book. The default setting is 0 (Slave Security enabled) which means, only a Master
which is in the Slaves’ Call Book may link to that Slave.
Slave Security may be disabled (setting of 1) allowing any Master to call the Slave. Slave Security has no
effect in Point-to-MultiPoint networks where the Network ID is not set to 255.
Slave Security must be set to 1 when the unit is operating in Mode 6 Slave/Master switchable or a Point-
to-Point network where the Slave may need to accept calls from more than 10 different Masters. When
Slave Security is set to 1, the transceiver will accept calls from any other FreeWave transceiver.
Additional network security measures may be taken to prevent unauthorized access, such as changing
default settings for FreqKey, Hop Table or Frequency Zones.
(7)
RTS TO CTS
The RTS to CTS setting in the Radio Parameters menu provides the option of allowing the RTS line on
the Master transceiver to control the CTS line of the Slave. This pass-through control can be enabled in
both Point-to-Point and Point-to-MultiPoint. In MultiPoint networks, the Master RTS line will control all
Slaves’ CTS lines. When enabled, the CTS line ceases to function as flow control. It is not recommended
to enable this feature when operating at RS-232 speeds above 38.4kB.
The default setting of 0 disables this function, where as a setting of 1 enables RTS-CTS control.
RTS-CTS setting 2 is described in detail in the application note #5437 “DTR to CTS Line Alarm Feature”.
With an RTS to CTS setting of 1, the Master senses the RTS line prior to all scheduled packet
transmissions. 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 being sent. If data is ready to be sent, 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 MultiPoint mode,