Multi-Tech Systems ISIHP-2U - Manual (Page 118)

118 MultiModemISI Hybrid Series, ISIHP-2S/2U/4S/4U/4SD
Terminal Adapter AT Commands & S-Registers
Controls how the TA responds to the DTR (Data Terminal Ready) signal. A
high DTR signal tells the TA that the connected computer is ready to
communicate.
&D0 TA ignores the DTR signal.
&D1 If DTR lowers when the TA is online, TA
hangs up, returns to command mode, and
disables autoanswer. If the TA is offline, it
doesn’t answer or dial while DTR is low.
&D3 When DTR lowers, the TA resets the data
port and disables autoanswer. If DTR lowers
when the TA is online, the TA hangs up,
resets the active configuration to the stored
configuration, and disables autoanswer.
&D4 &D4 will ignore DTR only 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.
Note: If you want to accept calls while DTR is low, the TA must be config-
ured to ignore DTR. This is accomplished by entering 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.
&En Flow Control
Values: n = 3–7, 12, 13
Default: &E4, &E6, &E13