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Chapter 6 – S-Registers
Multi-Tech Systems, Inc. AT Commands Reference Guide (S000273F) 43
Chapter 6 – S-Registers
Certain modem values, or parameters, are stored in memory locations called S-Rregisters. Use the S command to
read or alter the contents of the S-Registers.
S-Registers
S-Reg Unit Range Default Description
S0 1 ring 0,1–255 country dep. Number of Rings to Auto-Answer: Sets the number of rings required before the
modem automatically answers a call. ATS0=0 disables autoanswer completely.
S1 1 ring 0–255 0 Ring Counter: Counts the rings that have occurred.
S2 decimal 0–127 43 (+) Escape Character: Sets ASCII code for the escape sequence128–255
character. Values greater than 127 disable escape.
S3 decimal 0–127 13 (^M) Carriage Return Character: Sets the ASCII code for the carriage return character.
S4 decimal 0–127 10 (^J) Line Feed Character: Sets the ASCII code for the line feed character.
S5 decimal 0–32 8 (^H) Backspace Character: Sets the ASCII code for the backspace33–127
character. Values greater than 32 disable backspace.
S6 seconds 2–255 country dep. Wait Time Before Blind Dialing or for Dial Tone: Sets the time the modem
waits after it goes off-hook before it begins to dial the phone number.
S7 seconds 1–255 country dep. Wait Time for Carrier, Silence, or Dial Tone: Sets the time the modem waits for a
carrier signal before aborting a call. Sets the wait for silence time for the @ dial
modifier. Sets the time the modem waits for a dial tone after encountering W in the
dial string.
S8 seconds 0–255 2 Pause Time for Dial Delay: Sets the length of the pause caused by a comma
character in a dialing command.
S9 100 ms 1–255 6 Carrier Detect Response Time: Sets the time, in tenths of a second that the
carrier must be present before the modem considers it valid.
S10 100 ms 1–255 14 Lost Carrier to Hang Up Delay: Sets how long a carrier signal must be lost before
the modem disconnects.
S11 1 ms 50–255 country dep. DTMF Tone Duration: Sets spacing and duration of dialing tones.
S12 20 ms 0–255 50 Escape Prompt Delay (EPD): Defines the maximum period, in fiftieths of second,
allowed between receipt of the last character of the three escape character
sequences from the computer and the sending of the OK result code to the
computer (escape code guard time).
S13 decimal 0, 1–127 42 (*) Remote Configuration Escape Character: Sets the ASCII code for the remote
configuration escape character. ATS13=0&W disables remote configuration. For
use with the MT5600BA and MT5600BR only.
S15 minutes 0, 10–255 30 Dialup Backup: Sets the length of time the modem waits after making a dial-up
connection before it checks for a restored lease line. Zero disables dial backup. For
use with the MT5600BA and MT5600BR only.
S17 minutes 0–255 1 Dialup Connection: Sets the length of time the modem waits after a lease line fails
before it attempts a dial-up connection. For use with the MT5600BA and
MT5600BR only.
S24 seconds 0–255 0 Sleep Inactivity Timer: Sets the number of seconds that the modem operates in
normal mode with no detected telephone or serial port activity before it enters low-
power sleep mode. The timer is reset upon any serial port or telephone line activity.
S25 10 ms (async) 0–255 5 Delay to DTR OFF: Sets the length of time that the modem1 ms
(sync) ignores DTR while taking the action specified by &D .
S26 10 ms 0–255 1 RTS to CTS Delay: When &R0 is commanded, sets the time after detecting an
OFF-to-ON transition on RTS before the modem turns CTSON. Applies to
synchronous operation only.