Appendix F – Modem AT Commands
72
Multi-Tech Systems, Inc. MultiAccess User Guide
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
.)
