Multi-Tech MultiModem ISIHI-2S, Manual

Page: 99 / 186

MultliModemISI Hybrid Series, ISIHI-2S 99
Chapter 5—TERMINAL ADAPTER AT Commands, S-Registers, Result Codes
T
erminal Adapter
&Cn DCD Control
Values: n = 0, 1, or 2
Default:
&C1 (DCD normal)
Controls behavior of the DCD (Data Carrier Detect) signal. Normally, the DCD goes high
when the TA establishes a connection and drops when the connection is lost. However,
you 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 a disconnect, then rises again. Register S10
defines how long the DCD signal remains low after a disconnect.
&Dn DTR Control
Values: n = 0, 1, 2, or 3
Default:
&D1 (Exits Data Mode and re-enters AT command mode)
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.
Note: If you want to accept calls while DTR is low, the TA must be configured 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
Selects method by which the TA controls the flow of data to and from the computer, to
prevent either device from accepting data faster than it can handle. The TA provides flow
control in both directions. When the TA halts data flow, it is called
flow control; when the
computer halts data flow, it is called pacing.
&E3 Disable flow control by the TA.
&E4
Hardware flow control.
&E4 causes the TA to use the CTS signal to regulate
flow control. When CTS goes low, data flow from the computer is suspended
until CTS goes high again. This method works with pacing, which uses the
RTS signal on pin 4. Hardware flow control cannot be enabled unless an error
correction protocol is selected.