Specifications

Si2457/Si2434/Si2415
20 Rev. 0.91
AT Commands
At powerup, the Si2457/34/15 is in the AT command mode. In command mode, the modem monitors the input
(serial or parallel) checking constantly for a valid command (AT commands are described in Table 9.)
Table 9. Basic AT Command Set (Command Defaults in Bold)
Command Action
$
Display AT command mode settings.
A
Answer incoming call
A/
Re-execute last command. This is the only command not preceded by “AT” or followed by a
<CR>.
Dn
Dial
The dial command, followed by 1 or more dial command modifiers, manually dials a phone
number:
Modifier Function
! or & Flash hook switch for FHT (U4F) ms (default: 500 ms)
, or < Pause before continuing for S8 seconds (default:
2 seconds)
; Return to AT command mode
@ Wait for silence.
G Polarity reversal detect. By placing the “G” character in
the dial string (i.e. ATDTG1), the Si2457/34/15 will
monitor the telephone line for polarity reversals. If a
busy tone is detected, the Si2457/34/15 will report
“POLARITY REVERSAL” if a polarity reversal was
detected or “NO POLARITY REVERSAL” if a polarity
reversal was not detected. In each case, the result
code is followed by “OK”. If the S7 timeout occurs
before a busy tone is detected, the Si2457/34/15 will
report “NO CARRIER”. Polarity reversal monitoring
begins after the last digit is dialed and ends when the
busy tone is detected or S7 timeout occurs.
Note: It is not possible to establish a modem connection
when using this command.
L Redial last number.
P Pulse (rotary) dialing—pulse digits: 0, 1, 2, 3, 4, 5, 6, 7,
8, 9
T Tone (DTMF) dialing—DTMF digits: *, #, A, B, C, D, 0,
1, 2, 3, 4, 5, 6, 7, 8, 9.
W Wait for dial tone before continuing for S14 seconds
(default: 12 seconds). Blind dialing modes X0, X1 and
X3 do not affect the W command.
If the DOP bit (U7A, bit 7) is set, the “ATDTW” com-
mand will cause the ISOmodem® to pause dialing and
either report an “OK” if a dialtone is detected or “NO
DIALTONE” if a dial tone is not detected.
En
Local DTE echo
E0
Disable
E1
Enable