Multi-Tech Systems MTA128ST-USB - Manual (Page 36)

36
MultiModemISDN User Guide
MTA128ST-USB
Note that whereas the &F0 reset command always restores the factory
default profile, the Z reset command restores either the factory default or the
stored profile, depending on how the &W command is set.
Command: &Cn
Function:
DCD Control
Values: n = 0, 1, or 2
Default: &C1 (DCD normal)
Description: Controls behavior of the DCD (Data Carrier Detect) signal (pin 8 on the
RS232E/V.24 interface). Normally, DCD goes high when the TA establishes a
connection and drops when the connection is lost. However, you also can
force DCD to remain high at all times or to remain high except for a brief
drop following a disconnect.
&C0 DCD is forced high at all times
&C1 DCD goes from low to high when TA establishes a connection (DCD
normal)
&C2 DCD drops briefly following disconnect, then goes high again. Register
S10 defines how long DCD signal remains low after disconnect
Command: &Dn
Function:
DTR Control
Values: n = 0, 1, 2, 3, or 4
Default: &D1 (exits data mode and re-enters AT command mode)
Description: Controls how TA responds to DTR (Data Terminal Ready) signal on pin 20 of
RS232E/V.24 interface. A high DTR signal tells the TA that the connected
computer is ready to communicate.
&D0
TA ignores the DTR signal
&D1 When DTR goes low, TA exits data mode and re-enters AT command
mode
&D2 If DTR goes low, when TA is on-line, the TA hangs up, returns to
command mode, and disables autoanswer. If TA is offline, it neither
answers nor dials while DTR is low.
&D3 When DTR goes low, TA resets the data port and disables
autoanswer. If DTR goes low when TA is online, TA hangs up, resets
active configuration to the stored configuration, and disables
autoanswer.
Note: If the user wants to accept calls while DTR is low, the TA must
be configured to ignore DTR. To do this, enter AT&D0<cr>. With this
configuration, the TA is able to accept calls while DTR is low. If this
configuration setting is not made, the TA rejects incoming calls until
DTR is high while the calls comes in.
&D4 Ignores DTR when answering a data call. If DTR is low when an
incoming data call is present, the TA will answer the call. If DTR
goes high during that call, nothing will happen. However, if DTR
goes high and then drops for the minimum time specified by S25,
then the call will be disconnected just as it would with &D1. &D4 is
the same as &D1, except that &D4 can answer a data call without
DTR and DTR can remain low for the duration of the call, but if DTR
goes high, then &D4 will behave like &D1.