A3LA-R User Guide Version A
Document Number: 451-93156-001A
19 of 158
2.
Disconnect the (Clear To Send) CTS, (Data Carrier Detect) DCD, DSR, DTR, Request To
Send (RTS), and Ring Indicator (RI) lines between the DTE and modem.
3.
Set AT&Dn to AT&D0 to ignore the DTR input from the DTE.
4.
Set AT&Kn to AT&K0 for no flow control or AT&K4 for XON/XOFF software flow control.
5.
The setting can be stored on the modem permanently (until another setting overwrites
it) so that it remains after a power cycle. The modem allows two profiles in which
settings are stored; choose either as a default profile. The relevant commands are &Wn
and &Yn.
a.
&Wn stores the present configuration in profile <n>, where <n> can be either 0 or
1.
b.
&Yn designates which profile is loaded after reset or power-up; <n> is either 0 or 1.
6.
Address any needs of the DTE separately.
WARNING: DO NOT use the modem’s input voltage to bring the DTR line high when the input
voltage is higher than 5 VDC. Supplying voltage higher than 5 VDC to the DTR line will
permanently damage the A3LA-R.
Note: The Iridium’s direct internet service when using the Windows-based Apollo client
requires DCD to be present; hence it is incompatible with a 3-wire serial configuration. The
direct internet with Apollo client is available only on the EMSS DoD gateway and NOT on the
commercial gateway.
2.3
DC
P
OWER
I
NPUT
The DC power input is through pins 4 & 16 (EXT_B+) and pins 3 & 17 (EXT_GND). Note that two
pins are provided for the external DC input, and two pins are provided for the associated
external ground input. This is done to distribute the current across two wires, and therefore all
four pins should be utilized in the external power connection. Keep cables used to supply power
to the A3LA-R as short as possible to prevent significant voltage drop, which can cause the
A3LA-R to malfunction during a data call, an SMS session, or an SBD session. Power reset by the
A3LA-R during a call indicates the DC power source is unable to sustain voltage above 4.0 V at
