13
AT&FØ
Load IBM (and all other computers except Macintosh) error correction/data compression
configuration. This command sets
\N7
.
If you need to set up your modem to make a direct connection, issue
AT \N7
.
Changing Your Active Configuration
Your modem’s AT commands let you change most of the active configuration settings by issuing
single commands. For example,
ATL3
sets your speaker volume to high, and it stays set to high
until you reset or turn off the modem. The following AT commands are particularly useful:
•
AT&FØ
resets the active configuration to a preset factory default configuration. These settings
meet most users’ needs.
•
AT&V
or
AT\S
(Feature #146) displays the active configuration.
•
AT&Wn
(where
n
is profile Ø or 1) saves the active configuration in modems with memory.
•
ATZn
(where
n
is profile Ø or 1) resets the modem and loads the stored configuration from
profile Ø or 1. (Use ATZ for K56 modems.) Generally, this should be used at the end of the
initialization string because commands after it will not be read by the resetting modem.
The command
ATSr?
displays the value in S Register r. For example,
ATSØ?
reads S Register Ø
and displays three digits — ØØ4 if the value is 4.
The command
ATSr=n
writes the value
n
into S register r. Occasionally, you may need to change a
setting by issuing the
ATSr=n
command. The
n
must be a decimal integer from Ø to 255. For
example, the command
ATSØ=4 [CR]
sets register SØ to 4, which causes the modem to
automatically answer all incoming calls after the fourth ring. The modem replies with
OK
.
However, if you have a choice, use an AT command to change S Registers indirectly rather than
using the
ATSr=n
command.
Using AT Commands is addressed in Chapter 3. The AT Commands are published in Appendix B,
and the S Registers are published in Appendix C.
C
ONNECTION
R
ATES
How the Modem Determines Connection Speed and Protocol
The modem first tries to connect to the remote modem at the highest rate it supports (56,000 bps).
If the remote modem can’t connect at your modem’s highest rate, your modem tries to connect at
the next highest rate (54,000 bps). If that doesn’t work, it continues trying the remaining supported
speeds, one at a time in descending order. This process is called fall back.
If error correction and data compression are enabled (they are when shipped), the modem next
