Multi-Tech Systems ISIHP-2U - Manual (Page 94)

94 MultiModemISI Hybrid Series, ISIHP-2S/2U/4S/4U/4SD
Modem AT Commands & S-Registers
Modem S-Registers
S-registers are small regions of memory where modem configuration
information is stored. Whereas AT commands tell a modem what to do, S-
registers tell the modem how to do it. Each S-register has a name that
consists of the letter S and a number (S0, S1, S2, etc.), hence the term S-
register. Use the Sr? command to read the value stored in an S-register and
the Sr=n command to change it.
S0 Number of Rings Until Modem Answers
Unit: 1 ring
Range: 0–255
Default: 0
Defines number of rings the modem waits before answering an incoming
call. Default value is zero, which effectively disables the auto-answer
function. When auto-answer is disabled, the modem can only answer via the
ATA command. Set the S0 register value to one to cause the modem to
answer the call immediately after the first ring. Maximum number of rings
that can be configured is 255.
S1 Ring Count
Unit: 1 ring
Range: 0–255
Default: 0
Counts number of rings that have occurred. It is a read type of register and
is seldom used in typical operation. Each time an incoming ring signal is
detected, S1 increases its value by one, up to a maximum of 255. If you set
S1 to a value other than its default value of zero, or if the value is increasing
with rings, this new value remains stored in S1 for eight seconds after the
last ring is counted, after which the value reverts back to zero.
S2 Escape Code Character
Unit: Decimal
Range: 0–255
Default: 43 (+)
Defines escape code character by its decimal ASCII code. Default character
is the plus (+) sign (decimal 43). S2 can be set for any ASCII character.