Appendix F – Modem AT Commands
Multi-Tech Systems, Inc. MultiAccess ACS User Guide
50
Command: &C
n
Data Carrier Detect (DCD) Control
Values:
n
= 0, 1, 2
Default: 1
Description:
&C0 Forces the DCD circuit to be always ON.
&C1 DCD goes ON when the remote modem’s carrier signal is detected, and goes OFF
when the carrier signal is not detected.
&C2 DCD turns OFF upon disconnect for time set by S18. It then goes high again (for some
PBX phone systems).
Command: &D
n
Data Terminal Ready (DTR) Control
Values:
n
= 0, 1, 2, or 3
Default: 2
Description:
&D0 Modem ignores true status of DTR signal and responds as if it is always on.
&D1 If DTR drops while in online data mode, the modem enters command mode, issues
an
OK
, and remains connected.
&D2 If DTR drops while in online data mode, the modem hangs up. If the signal is not
present, the modem will not answer or dial.
&D3 If DTR drops, modem hangs up and resets as if
ATZ
command were issued.
Command: &E
n
XON/XOFF Pacing Control
Values:
n
= 12 or 13
Default: 12
Description:
&E12
Disables
XON/XOFF
pacing.
&E13
Enables
XON/XOFF
pacing.
Command: &F
n
Load
Factory
Settings
Values:
n
= 0
Default: None
Description:
&F0 Load factory settings as active configuration.
Note:
See also the
Z
command.
Command: &G
n
V.22bis
Guard
Tone
Control
Values:
n
= 0, 1, or 2
Default: 0
Description:
&G0 Disable guard tone.
&G1 Set guard tone to 550 Hz.
&G2 Set guard tone to 1800 Hz.
Note:
The
&G
command is not used in North America.
Command: &K
n
Flow
Control
Selection
Values:
n
= 0, 3, or 4
Defaults:
3
Description:
&K0 Disable flow control.
&K3 Enable CTS/RTS hardware flow control.
&K4 Enable XON/XOFF software flow control.
