Information Technology Reference
In-Depth Information
C
Modem Codes
C.1 AT commands
The AT commands are preceded by the attention code AT. They are:
A
Go on-line in answer mode
Instructs the modem to go off-hook immediately and then make a connection with a remote mo-
dem
Bn
Select protocol to 300 bps to 1200 bps
B0
Selects CCITT operation at 300 bps or 1200 bps
B1
Selects BELL operation at 300 bps or 1200 bps
D
Go on-line in originate mode
Instructs the modem to go off-hook and automatically dials the number contained in the dial string
which follows the D command
En
Command echo
E0
Disable command echo
E1 Enables command echo (default)
Fn
Select line modulation
F0
Select auto-detect mode
F1
Select V.21 or Bell 103
F4
Select V.22 or Bell 212A 1200 bps
F5
Select V.22bis line modulation.
F6
Select V.32bis or V.32 4800 bps line modulation
F7
Select V.32bis or V.32 7200 bps line modulation
F8
Select V.32bis or V.32 9600 bps line modulation
F9
Select V.32bis 12000 line modulation
F10
Select V.32bis 14400 line modulation
Hn
Hang-up
H0
Go on-hook (hang-up connection)
H1
Goes off-hook
In
Request product code or ROM checksum
I0
Reports the product code
I1/I2
Reports the hardware ROM checksum
I3
Reports the product revision code
I4
Reports response programmed by an OEM
I5
Reports the country code number
Ln
Control speaker volume
L0
Low volume
L1 Low volume
L2
Medium volume (default) L3 High volume
Mn
Monitor speaker on/off
M0/M
Speaker is always off
M1 Speaker is off while receiving carrier (default)
M2
Speaker is always on
M3 Speaker is on when dialing but is off at any other time
Nn
Automode enable
N0
Automode detection is disabled
N1 Automode detection is enabled
On
Return to the on-line state
O0
Enters on-line data mode with a retrain
O1
Enters on-line data mode without a retrain
P
Set pulse dial as default
Q
Result code display
Q0
Send result codes to the computer
Q1
No return codes
Sn
Reading and writing to S registers
Sn?
Reads the Sn register
