Iridium Communications, Inc. Information Contained in this Guide
Iridium 9523 Product Developers’ Guide is Subject to Change Without Notice
Revision 2.6
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Signal Description
RI
Active low ring indicator output
The Iridium 9523 drives RI ON when it receives an Automatic Notification from the
network that a Mobile Terminated SBD Message is queued at the Gateway, and drives
RI OFF after 5 seconds or when the FA initiates an SBD session, whichever occurs first
DCD
Active low handshaking output
The Iridium 9523 drives DCD ON to indicate that the Iridium link is active
Note that the Ring Indicator (RI) pin is used by the Iridium 9523 to indicate that a Mobile Terminated SBD
(MT-SBD) message is queued at the Gateway. The Field Application can monitor this pin and use
appropriate AT Commands to command the Transceiver to retrieve the MT-SBD message.
The serial interface may be operated with a 3-wire connection, where only transmit, receive and ground
signals are used. The Voice and Data Modem supports XON/XOFF flow control, which can be enabled
using the AT&Kn command, but the amount of buffering is restricted by its limited buffer space and
processing resources. There is therefore a risk of over-run and data loss, especially at high baud rates,
so the use of a 9-wire interface is recommended whenever possible.
When operating with a 3-wire connection, the following rules apply:
AT&Dn must be set to AT&D0 to ignore the DTR input
AT&Kn must be set to AT&K0 to disable RTS/CTS flow control
The other output signals may be connected, and operate as follows:
o CTS driven ON (low)
o DSR operates as normal
o RI operates as normal
o DCD operates as normal
Notes:
1. RTS/CTS flow control, when enabled, is only used when the data port is in data mode. In AT command
mode, RTS is ignored and CTS is driven ON (low).
2. If the DC input to the modem is to be disconnected, the developer will need to “tri-state” the serial
interface to prevent a possible latch-up condition.
3.5.2 Configuration Settings
The Iridium 9523 allows the FA to configure the data port communication parameters. The three
configuration types are active, factory default, and stored. The active configuration is the set of
parameters currently in use. They can be changed by the FA individually via specific AT commands. The
factory default configuration is stored in permanent memory. This configuration can be recalled at any
time through use of the AT&Fn command.
Two groups of settings, or “profiles”, can be stored as user-defined configurations. The FA first creates
desired active configurations and then writes them to memory using the AT&Wn command. These
profiles can be designated to be loaded as the active configuration upon Iridium 9523 power-up through
use of the AT&Yn command. The Iridium 9523 can be reset without loss of power to these profiles
through use of the ATZn command.
The configuration settings are stored in “S-register” locations and are detailed further in Section 6.
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