Multitech ISIHI-2S User Manual page 99

&RFn CTS/RTS Interaction Control
Unit: decimal ASCII code
Range: n=0 (CTS follows RTS when on-line),
n=1 (CTS is independent of RTS when on-line)
Default: n=1 (CTS is independent of RTS when on-line)
In normal operation, Clear-to-Send (CTS) follows Request-to-Send (RTS) when the modem is
on-line. In other words, if RTS goes off, CTS goes off in response. The &RF0 command
enables CTS to follow RTS. In some applications, however, it may be necessary for CTS to
operate independently of RTS. &RF1 allows CTS to operate independently regardless of the
state of RTS, and is the factory default. If this is the case, see the &R command for control of
the Clear-to-Send signal. The &RF command has effect only when using &R0 (CTS acts
normally—CTS follows RTS).
&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 reenters 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.
&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
Chapter 5 - AT Commands
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