User guide

4 AT Commands, S-Registers, and Result Codes

S-Registers

Certain modem values, or parameters, are stored in memory locations called S-

registers. Use the S command to read or alter the contents of S-registers (see

previous section for the Sn command).

S0 1 ring 0–255 1 Sets the number of rings before the modem

answers. ATS0=0 disables autoanswer

completely. The Range changes by country.

S1 1 ring 0–255 0 Counts the rings that have occurred.

S2 decimal 0–255 43 (+) Sets ASCII code for the escape sequence

character. 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. Values greater than 32 disable

backspace.

S6 seconds 2–255 2 Sets the time the modem waits after it goes

off-hook before it begins to dial the phone

number.

S7 seconds 1–255 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,

and the time the modem waits for the dial

tone after encountering W in the dial string.

S8 seconds 0–255 2 Sets the length of the pause caused by a

comma character in a dialing command.

S9 tenths/second 1–255 6 Sets the time, in tenths of a second, that the

carrier must be present before the modem

considers it valid.

S10 tenths/second 1–255 14 Sets how long a carrier signal must be lost

before the modem disconnects.

S11 1 ms 50–255 95 Sets spacing and duration of dialing tones.

S12 20 ms 0–255 50 Defines the maximum period, in fiftieths of

second, allowed between receipt of the last

character of the three escape character

sequence from the computer and the

sending of the OK result code to the

computer. (Escape code guard time).