User guide

2
Older models required 9V - 15V. Models are listed on page 28, and you can check the
model of your unit from the label on the bottom of it.
10 1892 1139 - RSX Range of Intelligent Modems User Guide - v7.1 / Nov 2007
Note: The information in this section applies to normal operation, and not to the PGM (pin
9) and Readback (pin 1) interface during radio programming.
1.2.4 Power Supply and Current Consumption
The RSXn50 requires a power supply of 5 to 15V DC (12V DC nominal)
2
. Because the
circuitry includes switched-mode power supplies, the current consumed varies inversely
with input voltage, and the external power supply must be capable of supplying the
corresponding current shown in the table below.
Input
State
5V 9V 12V 15V
Standby 100mA 70mA 60mA 50mA
RX 120mA 80mA 70mA 60mA
TX 5mW 120mA 80mA 70mA 60mA
TX 500mW 400mA 250mA 200mA 160mA
Table 2 - Supply current for various input voltages and activities
Note: Connection to a vehicle supply without proper external transient suppression can
cause the internal configuration data to be corrupted. Under these circumstances
the modem will revert to the default modem settings.
1.3 DURING OPERATION
1.3.1 Control Signals
The RSXn50 modem uses hardware flow control. Whenever customer equipment wishes
to send data, it should ensure that RTS is high. Provided it is answered with CTS high
from the RSXn50, it may start to send serial data at any of the permissible rates (see
specification). Do not send data with RTS low, as this could be interpreted as a command
code.
The RSXn50 brings CTS low if its transmit buffer becomes full and it cannot accept further
data to transmit at present. CTS is also brought low if transmission is not possible
because the squelch has operated, indicating received signals on the channel (provided
the option to override it has not been enabled). Any data sent during this condition will be
lost.
The DCD line is brought high to indicate that a signal is being received (squelch is open).
Received data is output to the customer equipment.