User's Manual

38 MDS TransNET I&O Guide MDS 05-2708A01, Rev. D
pass. Pin descriptions for EIA-232 are on page 69 and EIA-485 can be found
on page 71.
PWR [20–30]
Radio Transmitter Power Level
This command displays or sets the desired RF power output of the radio. The
PWR command parameter is specified in dBm and can be adjusted in 1 dBm
steps. The default setting is 30 dBm (1 watt) for the 900 MHz model and
27 dBm (0.5 watt) for the 2400 MHz model. To read the actual (measured)
power output of the radio, use the SHOW PWR command.
In the USA, maximum allowable power is governed by FCC limits on Effec-
tive Isotropic Radiated Power output (EIRP). The EIRP limit of +36 dBm on
the 900 and 2400 MHz band, means that any user with a net antenna gain
greater than 6 dBi on the 900 MHz band, or 9 dBi on the 2400 MHz band,
must decrease the PWR setting accordingly. “How Much Output Power Can
be Used?” on Page 12 contains a detailed discussion of this topic.
REPEAT [0–10]
Downstream Repeat Transmission Count
The REPEAT command affects “downstream” data. The command causes a
Master or Extension to always repeat transmissions for the specified number
of times (range is 0 to 10; default selection is 3). Unlike the RETRY command,
there is no acknowledgment that a message has been received.
Use the REPEAT command without a value to display the current setting.
RETRY [0–10]
Upstream Repeat Transmission Count
The RETRY command affects upstream data. The command selects, or
displays, the maximum number of times (0 to 10) that a Remote radio will
re-transmit data. The default setting is 10.
This command is associated with ARQ (Automatic Repeat Request) opera-
tion of the radio and is intended for use in areas with heavy radio interference.
When the RETRY command is issued without parameters, the maximum
retransmission count is shown. A value of 0 represents no retries, while
values of 1 or greater successively improve the chance of data delivery in
spectrally harsh environments (at the expense of possibly increased latency).
The RETRY value is only setable at the Master. It is readable by a synchro-
nized Remote.
RSSI
Received Signal Strength Indicator
This command displays the radio’s Received Signal Strength Indication in
dBm (decibels relative to 1 mW). The output can range from –40 dBm to
–120 dBm. Command availability and results depend on the mode of opera-
tion (Master or Remote). The closer to 0 dBm, the stronger the signal, thus a
reading of –70 dBm is stronger than –80 dBm.