5.9
SNM15
AT Command Set Description
Digicom SpA
AT&C
Selects the mode for handling criteria C109 (DCD) and C107
(DSR).
&C0
= C107 and C109 forced ON
&C1
= C107 and C109 handling depends on the selected
modulation standard.
&C2
= C107 forced ON.
&C3
= C109 forced ON.
&C4
= C109 is always ON; during disconnection it goes
OFF for 2 seconds then comes back to ON.
It has been implemented for use of modem when a
transition to OFF of DCD (C109) is necessary in
order to close the communication port and viceversa
C109 is necessary to open the communication port
and to send the programming string to the modem.
&C5
= a fall of C108 (DTR) causes a transition to OFF of
C107 (DSR) and C109 (DCD) for 500 ms.
This happens either when modem is OFF-LINE or
when it is ON-LINE. When ON-LINE, in case the
carrier falls, DSR and DCD go to OFF for 500 ms.
This function is very useful for modems used in
UNIX and XENIX applications.
