User Manual

Appendix A
Modem AT Commands
35
Xircom Inc. Mini PCI User’s Guide
Modem S-Registers
This section provides the following information:

Introduction to S-Registers

S-Register Reference
Introduction to S-Registers
The Xircom modem uses memory storage locations, or S-Registers, to hold information
controlling its operating environment. Few of these S-Registers require attention from modem
users. S-Registers are used in conjunction with Modem AT Commands.
To display the value of an S-Register, type ATSn? where n is the number of the S-Register, then
press Enter.
To modify the value of an S-Register, type ATSn=r where n is the S-Register number and r is the
new value or setting, then press Enter.
S-Register Reference
S0 Ring to Answer After
• The contents of register
S0
sets the number of rings required before the modem goes off-hook to answer an
incoming call (auto answer). The value can range from 0 to 255.
ATS0=0
disables the auto-answer
function. The default is 0.
S1 Ring Counter
• This register is read only. The value of S1 increments with each ring. If no rings occur over a six-second
interval, the register is cleared. The value of
S1
can range from 0 to 255. The default is 0. There may be
country-specific limits.
S2 AT Escape Character
• Register S2 defines the ASCII character used in the Escape sequence. This command is used to return to
command mode without losing the connection with a remote modem. Default is
S2=43
, which is the "+"
character. Thus the default Escape sequence is
+++
. ASCII values 127 and below can be used. To disable
this Escape sequence, set S2 equal to a value greater than 127.
S3 Command Line Termination Character
• This register contains the ASCII value of the command line terminating character (carriage return). The
factory default value is
ASCII 13
- the carriage return character. You can set register
S3
to any value
between 0 and 127.