A3LA-RS Quick Start Guide Version A
Document Number: 451-92899-002A
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2.2
RS232
D
ATA
I
NTERFACE
(S
TANDARD
9-W
IRE
C
ONFIGURATION
)
The A3LA-RS supports a standard RS232 data interface to a DTE incorporating hardware
handshaking and flow control. The RS232 data interface comprises eight standard RS232 data,
control and status signals, plus a ground-level signal reference, as shown in Table 1. This
interface allows a connected DTE to utilize the A3LA-RS’s modem functionality through
standard AT and extended sets of AT commands. These commands are defined in the A3LA-RS
User Guide Rev A [1].
2.3
DC
P
OWER
I
NPUT
The DC power input is through pin 1 (EXT_B+) and pins 3 & 8 (EXT_GND). Keep cables used to
supply power to the A3LA-RS as short as possible to prevent significant voltage drop, which can
cause the A3LA-RS to malfunction during a data call, SMS session, or SBD session.
2.4
P
OWER
O
N
/O
FF
C
ONTROL
With the EXT_ON_OFF pin left unconnected, the A3LA-RS automatically turns on or off when
external DC power is applied or removed. Prior to turning off the A3LA-RS, issue command
AT*P0 to ensure all memory write activity is completed. When the A3LA-RS is powered off, its
internal power-on-reset circuit requires two seconds for voltages to decay. Do not reapply
power until this time has elapsed. The EXT_ON_OFF pin can be connected to an external I/O
control line to turn a powered A3LA-RS on and off in a toggle fashion.
2.5
T
YPICAL
P
OWER
U
SAGE
P
ROFILE
Optimize your setup to attain the lowest possible power consumption. Some setup parameters
to carefully observe include:
1.
Have a clear view of the sky for the antenna.
2.
Keep the antenna’s voltage standing wave ratio (VSWR) low to minimize power
consumption.
3.
Keep the antenna cables’ loss to less than 3 dB.
4.
Keep the power cable between the A3LA-RS and the power source as short as possible.
