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Configuring the Modem 4-17
Configuring
the Modem
Option Set 1—Async Calls to Central Site Using AT ACU
Changing Default Configuration Settings
Depending on application requirements, you may need to change the following:
• Buffer Delay (AT
*
DB, EC/DC OPTS category), when enabled, allows
buffered data in the communications link to be effectively transmitted to the
other modem before the modems disconnect. Enable this feature if your
application does not ensure a complete transfer of data before the modems
disconnect.
• When the 326X is configured for Option Set 1: if you do not use the AT ACU
to send commands to operate the modem, you must customize the DTE port by
selecting these options:
— DTE Rate. Set the modem’s DTE rate to match the asynchronous DTE’s
rate using the DTE Rate option (AT
*
DE, TERMINAL OPTS category).
— Parity. Set the modem’s parity to match the parity set in the asynchro-
nous DTE using the Parity option (AT
*
RP, ACU OPTS category).
— Character Length. Set the modem’s character length (Char Length,
ACU OPTS category) to match the length set in the asynchronous DTE.
(Refer to Appendix A for parameter and setting descriptions.)
• In Option Set 1, the default settings assume you will use the AT ACU to oper-
ate the modem (for example, the default for ACU Select=AT; EIA signals are
set high). If you plan on using DTR transitions (“DTR Dialing”) to signal the
modem to make a call (rather than AT Commands), do the following:
1) Set Default Dial=1 (AT
*
DA, ACU OPTS category).
2) Store a number in memory location 1 (using Enter Phone #, AT&Z,
9600 T/D? category).
3) Set DTR=108.1 (AT&D, TERMINAL OPTS category). When DTR is
raised, the modem will dial the specified call.
• If the DTE does not require EIA signal pins to be held high, adjust the EIA
settings (TERMINAL OPTS category) to match your application requirements.
• In Option Set 1, the modem is set for XON/XOFF (software) flow control. If
your application requires hardware flow control, change the Flow setting
(AT
*
FL, TERMINAL OPTS category).