NAL A3LA-XM, Общее описание устройства

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NAL Research Corporation (TN2009-25-V1.0)
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3.1 RS232 Data Interface (Standard 9-Wire Configuration)
The A3LA-XM supports a standard RS232 data interface to a DTE incorporating hardware handshaking
and flow control. The RS232 data interface comprises of eight standard RS232 data, control and status
signals plus a ground level signal reference as shown in Table 1 (pins 7-RI, 8-RTS, 9-TX, 10-DCD, 13-RX,
19-DTR, 21-DSR, 22-CTS and 23-GND). This interface allows a connected DTE to utilize the A3LA-XM‘s
modem functionality through standard AT and extended sets of AT commands. These commands are defined
in the document AT Command Reference for Model A3LA-XM. The A3LA-XM will automatically adjust to the
DTE baud rate and override the +IPR setting when dissimilar. Autobaud will occur on the following ‗U‘
character.
3.2 RS232 Data Interface (3-Wire Configuration)
Several steps must be taken to allow 3-wire configuration (i.e. only using S_TX, S_RX, and SIGNAL
GND). These steps ensure the A3LA-XM and DTE to work together without having hardware handshaking.
1. The modem‘s DTR line must be held high. Using the modem‘s input voltage is fine for this purpose
BUT ONLY if the input voltage is less than 5VDC (see important note below). Looping back the
modem‘s DSR line to DTR line will NOT work. The DSR line on the modem should be left
unconnected.
2. Disconnect the CTS, DCD, DSR, DTR, RTS and RI lines between the DTE and modem.
3. AT&Dn must be set to AT&D0 to ignore the DTR input from the DTE.
4. AT&Kn must be set 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, and user
can choose either as a default profile. The relevant commands are &Wn and &Yn. &Wn stores the
present configuration in profile <n>, where <n> can be either 0 or 1. &Yn designates which profile
is loaded after reset or power-up, again <n> is either 0 or 1.
6. Any needs of the DTE must be addressed separately.
NOTE: DO NOT use the modem‘s input voltage to bring the DTR line high when the input voltage
is higher than 5VDC. Supplying voltage higher than 5VDC to the DTR line will permanently damage
the A3LA-XM.
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.
3.3 USB Data Interface
The A3LA-XM is shipped with hardware set to RS232 serial interface. However, it can be changed to USB
2.0 through two internal rotary switches. These switches can be found by removing the modem‘s bottom
plate. With the A3LA-XM held in the position shown in Figure 2 (DB25 connector on the right side and TNC
antenna connector on the left side), the A3LA-XM is set for serial interface when the grove on both rotary
switches are in the ‗\‘ position and is set for USB interface when the grove on both rotary switches are in the