3Com U.S. Robotics 56K Voice, Command Reference Manual

Page: 62 / 210

7-2 C
HAPTER
7: C
ONTROLLING
EIA-232 S
IGNALING
Data Set Ready
Under normal conditions, the Business Modem sends a Data Set Ready
(DSR) signal to your computer when it is ready to send and receive data.
CAUTION: Do not change the default setting of &S0 unless you know
that your installation requires a different setting. Few Windows
communications programs, if any, will require the Business Modem to
control DSR (&S1).
Use the following command to control how the modem sends the DSR
signal.
Example: Issuing
AT&S3
configures the Business Modem to send a
pulsed DSR signal after sending the Carrier Detect (CD) signal.
For you modem Command
To send the DSR signal at all times.
AT&S0
(Default)
When originating a call, to send the DSR signal after dialing
when the Business Modem detects the remote analog device’s
answer tone
AT&S1
When answering a call, to send DSR after the Business Modem
sends its answer tone.
AT&S1
After sending Carrier Detect (CD), to send a pulsed DSR signal,
followed by a Clear to Send (CTS) signal. Use this option for
specialized equipment such as automatic callback units.
AT&S2
After sending Carrier Detect (CD), to send a pulsed DSR signal.
AT&S3
To send a DSR signal to your computer at the same time the
Business Modem sends the CD signal.
AT&S4
To send DSR normally (with CTS) after sending CD.
In order to change the DSR pulse time (in 20-second
increments), set S-Register 24. (See Appendix B,
Alphabetic
Command Summary ).
AT&S5