Intel 537EX manual S-Registers, Intel Confidential, S-RegisterCommand Descriptions

	S-Registers
S-Registers	7

The 536EX chipsets provide direct access to the internal registers known as S-registers. The DTE uses S-registers to set up and check modem configurations. The contents of these registers can be changed using the ATSn=x command, where ‘n’ is the register number and ‘x’ is the value to be stored. The contents of the S-registers can be read using the ATSn? command. Most S-registers can be read from or written to; however, some S-registers (such as S14) are read-only. Writing to a read-only register may cause the modem to act improperly (that is, even though the contents of a read-only S-register may be changed using the ATSn=x command, changing the contents of the S- register does not normally configure the entire modem).

Reserved S-registers are used by the modem and provide no valuable information to the DTE. These registers have been removed from the following table. Reserved S-registers should never be written to, as they cause the modem to lock up.

Table 26. S-Register Command Descriptions

Command	Default		Description
		Number of Rings to Auto-Answer On: Assigning S0 a value from 1 to 255 configures the
		modem for auto-answer mode. The modem automatically goes off-hook and initiates a data
		mode-answer mode handshake after detecting the specified number of rings. This S-register is
		meant for data modem mode only and should be set to ‘0’ for fax and voice modes.
		Range: 0–255 rings
S0	0	0	Auto-answer mode disabled
		1–255	Auto-answer mode enabled
		NOTES:
		• If Caller ID is enabled (+VCID=m), then the modem only answers after the second ring
		even if S0=1.
		• Setting n > 2 causes the modem to answer on the nth ring signal.
		Ring Count: Reports the number of ring signals detected by the modem. This register is cleared
S1	0	to zero if no new ring signals are detected within an 8 second time interval.
		Range: 0–255 rings
		Default: 0 rings
		Escape Character: S2 specifies an ASCII value for the Hayes or TIES escape character. The
		factory default is ‘+’ or ASCII decimal 43. The escape character may range between 0–127. Any
S2	43	value over 127 disables the escape sequence.
		Range: 0–127
		Default: 43 (‘+’)
		Carriage Return Character: S3 specifies the AT command string terminator and modem
S3	13	response code terminator. The factory default is a <CR> or carriage return (ASCII decimal 13).
		Range: 0–127
		Default: 13 (carriage return)
		Line Feed Character: S4 specifies the line feed character, which is used for verbose (text)
S4	10	modem result codes.
		Range: 0–127
		Default: 10 (line feed)
NOTE: An asterisk (*) denotes the factory-default setting.

536EX Chipset Developer’s Manual 85

Intel Confidential