V.22 bis Modem with AT Commands
CMX866
The escape sequence ‘+++’ (with Guard Time = 1s [see S12 register] before and after the sequence) will
cause the CMX866 to enter Command mode from Data Transfer mode and to return an ‘OK’ response.
1.5.4.3 AT Commands in Detail
Command
Description
A
Answer Command
The CMX866 will go off-hook and attempt to answer an incoming call by
establishing a connection with a remote modem. The command is not valid if there
is no incoming call and it will return the 'ERROR' result code.
Syntax: ATA<CR>
A/
Re-Execute Previous Command Line
Re-executes the last issued command line. This command does not require the AT
prefix or a carriage return. If the last issued command line contained several AT
commands, each of these will be repeated.
Syntax: A/
Bn
Select Communications Standard
Selects the communications standard specified by the parameter n.
Syntax: ATBn<CR>
Modifier Usage
n=0 Selects ITU-T V.22bis at 2400bps QAM (default).
n=1 Selects ITU-T V.22 at 1200bps DPSK.
n=2 Selects ITU-T V.23 with Tx 75bps and Rx 1200bps FSK.
n=3 Selects ITU-T V.23 with Tx 1200bps and Rx 75bps FSK.
n=4 Reserved for future use.
n=5 Selects ITU-T V.21 at 300bps FSK.
n=6 Selects Bell 212A at 1200bps DPSK.
n=7 Selects Bell 202 with Tx 150bps and Rx 1200bps FSK.
n=8 Selects Bell 202 with Tx 1200bps and Rx 150bps FSK.
n=9 Selects Bell 103 at 300bps FSK.
Dn
Dial Command
This command directs the CMX866 to go off-hook, dial the directory number
entered and attempt to establish a connection with a remote modem by going into
Data Transfer mode. The n represents an ASCII string composed of dial digits and
dial modifiers and must not exceed the 23 character buffer limit. The DTMF tone
dialling digits include 0 through 9, A, B, C, D, and the symbols # and *. Loop-
disconnect (pulse) dialling is not implemented.
or DTn
For example: ATD9,01621875500<CR>
Modifier Usage
n=L Re-dial last number.
n=,
n=!
n=;
Delay dial sequence (pause setting contained in S8 register).
Send a timed break recall (duration in S29 register).
Remain in command mode after dialling, no handshake.
En
Echo Command Characters
Syntax: ATEn<CR>
Modifier Usage
ã 2004 CML Microsystems Plc
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D/866/4
CMLMICRO [ CML MICROCIRCUITS ]
