Toshiba A50 S1 Ring counter, S2 AT escape character (user defined), S3 Command line termination character(user defined), S4 Response formatting character (user defined)

D-2 User’s Manual
S-registers
S1 Ring counter
This register is read only. The value of S1 is incremented with
each ring. If no ring occurs over a six-second interval, this register
is cleared.
Range:0-225
Default:0
Units:rings
S2 AT escape character (user defined)
This register determines the ASCII values used for an escape
sequence. The default is the + character. The escape sequence
allows the modem to exit data mode and enter command mode
when on-line. Values greater than 127 disable the escape
sequence.
Range:0-255, ASCII decimal
Default:43
Units:ASCII
S3 Command line termination character(user defined)
This register determines the ASCII values as the carriage return
character. This character is used to end command lines and result
codes.
Range:0-127, ASCII decimal
Default:13 (carriage return)
Units:ASCII
S4 Response formatting character (user defined)
This register determines the ASCII value used as the line feed
character. The modem uses a line feed character in command
mode when it responds to the computer.
Range:0-127, ASCII decimal
Default:10 (line feed)
Units:ASCII