Appendix 2: AT Command Set
Perle 833IS User Guide 263
S-Register Definitions
S3 - Carriage Return
Character Sets the command line and result code terminator character. Pertains to WAN
operation only.
Range: 0-127, ASCII decimal
Default: 13 (Carriage Return)
S4 - Line Feed
Character Sets the character recognized as a line feed. Pertains to WAN operation only. The
Line Feed control character is output after the Carriage Return control character if
verbose result codes are used.
Range: 0-127, ASCII decimal
Default: 10 (Line Feed)
S5 - Backspace
Character Sets the character recognized as a backspace. Pertains to WAN operation only. The
modem will not recognize the Backspace character if it is set to a value that is greater
than 32 ASCII. This character can be used to edit a command line. When the echo
command is enabled, the modem echoes back to the local DTE the Backspace
character, an ASCII space character and a second Backspace character; this means a
total of three characters are transmitted each time the modem processes the
Backspace character.
Range: 0-32, ASCII decimal
Default: 8 (Backspace)
S6 - Wait Time for
Dial Tone Before
Blind Dialing, or
After “W” Dial
Modifier (W-Class
Models)
 Sets the length of time, in seconds, that the modem will wait before starting to
dial after going off-hook when blind dialing. This operation, however, may be
affected by some ATX options according to country restrictions. The "Wait for
Dial Tone” call progress feature (W dial modifier in the dial string) will override
the value in register S6.
 For W-class models, S6 sets the length of time, in seconds, that the modem will
wait for dial tone when encountering a “W” dial modifier before returning NO
DIAL TONE result code.
The modem always pauses for a minimum of 2 seconds, even if the value of S6 is
less than 2 seconds.
Range: 2-255 seconds
Default: 2