Appendix F — Modem AT Command Set

Default values of command parameters, if applicable, are indicated by an asterisk (*).

Basic AT Commands

A/ Repeat Last Command

Repeats execution of the previous command string. “ A/” must not be preceded with AT, or followed by pressing <Enter>.

AAnswer

Causes the modem to go off-hook and attempt to establish a connection, even in the absence of a ring.

Bn Line Modulation Options

Configures the modem to the desired communications standard setting at a particular line speed.

B0: Selects CCITT V.22 mode when the modem is at 1200 bps, and CCITT V.21 when the modem is at 300 bps.

*B1: Selects Bell 212A when the modem is at 1200 bps, and Bell 103 when the modem is at 300 bps.

B2: Selects V.23 originate mode receive 1200 bps, transmit 75 bps; answer mode receive 75 bps, transmit 1200 bps.

B3: Selects V.23 originate mode receive 75 bps, transmit 1200 bps; answer mode receive 1200 bps, transmit 75 bps.

Result Codes:

OK

Returned when n = 0, 1, 2 or 3.

ERROR Returned for any other value of n.

Cn Carrier Control Option (no operation)

This command is included to provide backward compatibility with communications software that issues this command.

C0: Returns ERROR.

C1: Normal transmit carrier switching.

Result Codes:

OK

Returned when n = 1.

ERROR Returned for any other value of n.

Appendix F

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Digi 90031300 manual Appendix F Modem AT Command Set, Basic AT Commands