V.22 bis Modem with AT Commands
CMX866
1.5.4.4 Extended AT Commands
Command
Description
&Cn
Carrier Detect
Determines the action of the DCDN pin.
Syntax: AT&Cn<CR>
Modifier Usage
n=0 DCD is always on (DCDN pin is held permanently low).
n=1 DCD follows the received carrier. If a carrier is present on the line, then DCD
is on (DCDN pin is held low). Otherwise DCD is off (DCDN pin is held high)
(default).
&Dn
Data Terminal Ready
Determines the meaning of the DTRN pin.
Syntax: AT&Dn<CR>
Modifier Usage
n=0 DTRN pin is ignored
n=1 When an on to off transition of DTR occurs (DTRN pin goes from low to high),
the CMX866 goes into Command mode (if it was in Data Transfer mode), after a
fixed delay of 100ms, during which time the transition is qualified. Whilst in
Command mode, if DTRN remains high for more than 500ms, then the CMX866
goes on-hook.
n=2 Same as above (n=1), except that the CMX866 also goes on-hook when the
DTRN transition is qualified.
&Gn
Guard Tone Select
Selects the Guard tone to be transmitted with highband QAM or DPSK.
Syntax: AT&Gn<CR>
Modifier Usage
n=0 Disable guard tone (default).
n=1 Enable 550Hz guard tone.
n=2 Enable 1800Hz guard tone.
&Tn
Loopback Connection
Instructs the CMX866 to make local or remote loopback connections, or to action a
remote request to make loopback connections.
Syntax: AT&Tn<CR>
Modifier Usage
n=0 Remove all loopbacks and return to Data Transfer mode.
n=1 Reserved.
n=2 Reserved.
n=3 Make a local digital loopback connection to loopback the received data stream
from the remote modem.
n=4 Enable remote requests for a local digital loopback connection.
n=5 Disable remote requests for a local digital loopback connection.
n=6 Request a remote digital loopback connection.
ã 2004 CML Microsystems Plc
23
D/866/4
CMLMICRO [ CML MICROCIRCUITS ]
