MultiModemDSVD User Guide 4 AT Commands, S-Registers, and Result Codes
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Command: &C
n
Data Carrier Detect (DCD) Control
Values: n = 0 or 1
Default: 1
Description: &C0 Forces the DCD circuit to always be high.
&C1 DCD goes high when the remote modem’s carrier signal is de-
tected, and goes low when the carrier signal is not detected.
Command: &D
n
Data Terminal Ready (DTR) Control
Values: n = 0, 1, 2, or 3
Default: 2
Description: This command interprets the high to low transition of the DTR
signal from the computer according to the supplied parameter.
The action taken depends on the current &Q setting.
&D0 &Q0, &Q5, &Q6: DTR is ignored (assumed high). Allows op-
eration with computers that do not provide DTR.
&D1 &Q0, &Q5, &Q6: DTR drop is interpreted by the modem as if
the asynchronous escape sequence had been entered. The mo-
dem returns to asynchronous command state without discon-
necting.
&D2 &Q0–&Q6: DTR drop causes the modem to hang up. Autoan-
swer is inhibited.
&D3 &Q0, &Q5, &Q6: DTR drop causes the modem to perform a
soft reset as if the Z command were received. The &Y setting de-
termines which profile is loaded.
&Q5 or &Q6 and +FCLASS=1 or +FCLASS=2: Same as for &Q0.
Note: If &D1, &D2, or &D3 is set, the modem will not dial
without a DTR drop.
Command: &E
n
V.42 Error Correction Modes
Values: n = 0, 1, or 2
Default: 1
Description: &E0 V.42 non-error correction mode (V.42 disabled).
&E1 V.42 auto-reliable mode.
&E2 V.42 reliable mode (V.42 enabled).
Command: &E
n
Modem-Initiated Flow Control
Values: n = 3, 4, or 5
Default: 4
Description: &E3 Flow control disabled.
&E4 CTS/RTS hardware flow control.
&E5 XON/XOFF software flow control.
Note: See also the L5 and &K commands.