
INTEGRATED CIRCUITS DIVISION
CPC2400E
www.ixysic.com
9
R03
AT Command Set
Command
Function and Description
&D
Data Terminal &D determines how the modem responds to the DTR signal from the terminal. The country Ready
Options conguration may prevent the modem from detecting terminal DTR. In this case, the modem assumes DTR
is always on. In North America, terminal DTR is normally detected. If DTR detection has been prevented, the modem
will respond with an ERROR result to this command.
The response to changes in DTR also depends on the &Q and &D commands. This table denes what happens
when DTR goes off for all possible combinations of the &D and &Q commands. To see what happens when DTR
goes on refer to the &Q command. The default value is &D0 in North America:
&D0
&D1
&D2
D3
&Q0
None
B
C
D
&Q1
A
B
C
D
A
The modem hangs up the telephone line and issues an OK result code.
B
If in the On-Line state, the modem goes into the Command state and issues an OK result code.
C
The modem hangs up the telephone line and issues an OK result code. Auto-Answer is disabled as
long as DTR stays off.
D
The modem resets.
E
Command Mode E tells the modem whether or not to echo characters sent from the terminal when the modem is
Character Echo accepting AT commands.
E0
Does not echo characters sent from the terminal.
E1
Echo characters sent from the terminal. This is the default value in North America.
%E
Automatic Retrain
Options
The %E command controls whether the modem will initiate retrain with the other modem during a telephone line
connection during operation in data modes supporting retrain. The modem always responds to a retrain operation
initiated by the remote modem. The modem can be forced to initiate a retrain by the On-Line (O1) command.
%E0
Do not initiate a retrain.
%E1
Initiate a retrain if the datapump indicates one is required.
&F
Recall Factory
Prole
&F changes these AT command options and S-registers to their default values. The default values may be changed
for use in different countries. The values for North America are:
S-registers
S0=0 S1=0
S2=43
S3=13
S4=10
S5=8
S6=2 S7=30
S8=2
S9=6
S10=14
S11=95
S12=50
S17=10
S25=5
S28=0
S29=25 S37=0
Commands
B1
E1
M1
P
Q0
V1
X4
&C0
&D0
&G0
&P0
&Q0
%E1
&G
Guard Tone
Options
&G tells the modem which guard tone to transmit when the modem is transmitting the high band (i.e., answer
handshake and answer mode).
&G0
No guard tone. This is the default value in North America.
&G1
550 Hz guard tone (V.22 and V.22bis only)
&G2
1800 Hz guard tone (V.22 and V.22bis only)