US Robotics 56K USB Modem User Manual page 18

escape sequence character.
A/—Repeat Last Command
Use this command to repeat the last AT command. The modem repeats the command currently in the
command buffer. Do not use the AT prefix with this command. Do not conclude the command with a
terminating character such as enter.
A—Answer
Use this command to instruct the modem to connect to the line and establish a connection with the remote
modem or DCE. This command can be canceled if the modem receives a new command or character from
the host system before handshaking has begun.
Result codes:
• CONNECT if a connection is established and the extended result code parameter (X<value>—Select
Result Code and Monitor Call Progress on page 21) is equal to 0.
• CONNECT <rate> if a connection is established and the extended result code parameter is not equal
to 0.
• NO CARRIER if a connection cannot be established or the modem aborts the connection on request of
the host system.
• OK if the command is aborted or DTR is turned off by the host system when the data terminal ready
control (&D<value>—Data Terminal Ready (DTR) Control on page 24) is not set to 0.
• ERROR if the modem is in online command mode when receiving the A command.
B<value>—Communication Standard Setting
Use this command to select the communication standard used by the modem.
Result codes:
• OK if <value> = 0—3, 15, 16.
ERROR if <value> ≠ 0—3, 15, 16.
•
Table 3. B<value> Commands
Command
B0 Selects CCITT V.22 mode when the modem is at 1200 bits/s.
B1 Selects Bell 212A when the modem is at 1200 bits/s (default).
B2 Deselects V.23 reverse channel (same as B3).
B3 Deselects V.23 reverse channel (same as B2).
B15 Selects V.21 when the modem is at 300 bits/s.
B16 Selects Bell 103J when the modem is at 300 bits/s (default).
Function
56K USB Modem
User Guide
Command Reference - 12