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4-1
4. S-Registers
Certain modem values, or parameters, are stored in memory locations called
S-Registers. Use the S command to read or to alter the contents of S-Registers
(see previous section).
Register Unit Range Default Description
S0 1 ring 0, 1–255 1 Sets the number of rings until the modem answers.
ATS0=0 disables auto answer completely.
S1 1 ring 0–255 0 Counts the rings that have occurred.
S2 decimal 0–127 43 (+) Sets ASCII code for the escape sequence character.
128–255 Values greater than 127 disable escape.
S3 decimal 0–127 13 (^M) Sets the ASCII code for the carriage return character.
S4 decimal 0–127 10 (^J) Sets the ASCII code for the line feed character.
S5 decimal 0–32 8 (^H) Sets the ASCII code for the backspace character.
33–127 Values greater than 32 disable backspace.
S6 seconds 2–65* 2* Sets the time the modem waits after it goes off-hook
before it begins to dial the telephone number.
S7 seconds 35-65* 50* Sets the time the modem waits for a carrier signal
before aborting a call. Also sets the wait for silence
time for the @ dial modifier.
S8 seconds 0–65 2 Sets the length of a pause caused by a comma
character in a dialing command.
S9 decimal 0, 1–127 37 (%) Sets ASCII code for remote configuration escape
character. S9=0 disables remote configuration.
S10 100 ms 1–254 20 Sets how long a carrier signal must be lost before the
modem disconnects.
S11 1 ms 50–150* 95* Sets spacing and duration of dialing tones.
S28 decimal 0, 1–255 1 0 disables, 1–255 enables V.34 modulation.
S30 1 minute 0, 1–255 0 Sets the length of time that the modem waits before
disconnecting when no data is sent or received.
A value of zero disables the timer. See also
the \T command
S35 decimal 0–1 1 0 disables, 1 enables the V.25 calling tone, which
allows remote data/fax/voice discrimination.
S36 decimal 0–7 7 Specifies the action to take in the event of a
negotiation failure when error control is
selected. (See S48.)