3COM CORPORATION

BIT-MAPPED REGISTER S13
Format		AT [cmds] S13=n [cmds]
Example:		ATS13=139<CR>
Default:		0
Range:		0 - 89
Unit:		Bit-mapped
Description:		Controls DTR reset, DTR dialing, reset dialing, and MNP3.
Bit	Value		Function
0	� 0 1		DTR normal. Reset on low DTR.
1	� 0		Not used.
2	� 0		Not used.
3	� 0 1		DTR dialing disabled. DTR dialing enabled.
4	� 0 1		Reset dialing disabled. Reset dialing enabled.
5	� 0		Not used.
6	� 0 1		MNP 3 enabled. MNP 3 disabled.
7	� 0		Not used.

BIT-MAPPED REGISTER S15
Format		AT [cmds] S15=n [cmds]
Example:		ATS15=139<CR>
Default:		0
Range:		0 - 56
Unit:		Bit-mapped
Description:		Controls non-error-correcting mode buffer, MNP4, and BS/DEL switch.
Bit	Value		Function
0	� 0		Not used.
1	� 0		Not used.
2	� 0		Not used.
3	� 0 1		Non-error-correcting mode transmit buffer set to 1.5KB. Non-error-correcting mode transmit buffer set to 128 bytes.
4	� 0 1		MNP 4 enabled. MNP 4 disabled.
5	� 0 1		Use backspace key for delete disabled. Use backspace key for delete enabled.

BIT-MAPPED REGISTER S27
Format		AT [cmds] S27=n [cmds]
Example:		ATS27=139<CR>
Default:		0
Range:		0 - 191
Unit:		Bit-mapped
Description:		Controls V.21, V.32 encoding and modulation, V.42 answer tone and handshake, and 9600 result codes.
Bit	Value		Function
0	� 0 1		V.21 disabled. V.21 enabled.
1	� 0 1		V.32 trellis coding disabled. V.32 trellis coding enabled.
2	� 0 1		V.32 modulation enabled. V.32 modulation disabled.
3	� 0 1		2100Hz answer tone enabled. 2100Hz answer tone disabled.
5, 4	� 00 01 10 11		V.42 detect, LAPM and MNP enabled. V.42 detect and LAPM enabled. MNP enabled. LAPM enabled.
6	� 0		Not used.
7	� 0 1		Actual result codes displayed. Force 9600 result codes.

COMPRESSION AND ERROR CORRECTION
Format		AT [cmds] S51=n [cmds]
Example:		ATS51=139<CR>
Default:		0
Range:		0 - 7
Unit:		Bit-mapped
Description:		Selects compression and error correction for specific modulations.
Bit	Value		Function
0	� 0 1		MNP/V.42 disabled during V.22 operation. MNP/V.42 disabled during V.22 operation.
1	� 0 1		MNP/V.42 disabled during V.22bis operation. MNP/V.42 disabled during V.22bis operation.
2	� 0 1		MNP/V.42 disabled during V.32bis operation. MNP/V.42 disabled during V.32bis operation.

BREAK LENGTH
Type:	Register
Format:	AT [cmds] S21=n [cmds]
Example:	ATS21=20<CR>
Default:	10
Range:	Unidentified
Unit:	10 milliseconds
Description:	Sets the length of error control mode breaks sent from DCE to DTE.

BREAK TYPE
Type:	Configuration
Format:	AT [cmds] &Yn [cmds]
Example:	AT &Y0<CR>
Description:	Configures action of break signal.
Command	Function
&Y0	Break empties buffer.
� &Y1	Break empties buffer and is sent immediately.
&Y2	Break does not empty buffer and is sent immediately.
&Y3	Break does not empty buffer and is sent with transmitted data.

CONNECTION SPEED FORCE
Type:	Configuration
Format:	AT [cmds] &Nn [cmds]
Example:	AT &N1 DT555-1212<CR>
Description:	Sets required connection speed.,
Command	Function
� &N0	Variable.
&N1	300bps
&N2	1200bps
&N3	2400bps
&N4	4800bps
&N5	7200bps
&N6	9600bps
&N7	12Kbps
&N8	14.4Kbps

ERROR CORRECTION MODE
Type:	Configuration
Format:	AT [cmds] &Mn [cmds]
Example:	AT &M1 %C1<CR>
Description:	Selects active error correction protocols.
Command	Function
&M0	Normal mode only.
� &M4	Auto-detect mode.
&M5	ARQ mode only.

ESCAPE CHARACTER RESPONSE
Type:	Register
Format:	AT [cmds] S14=n [cmds]
Example:	ATS14=20<CR>
Default:	0
Description:	Controls reaction to escape character.
Command	Function
� S14=0	Normal operation.
S14=1	When +++ is received, modem goes on hook, enters command state and sends NO CARRIER result code.

EXTENDED RESULT CODES
Type:	Configuration
Format:	AT [cmds] &An [cmds]
Example:	AT &A1 %C1<CR>
Description:	Selects extended result codes.
Command	Function
&A0	Extended result codes disabled.
&A1	ARQ result codes enabled.
&A2	V.32 result code enabled.
� &A3	Error control and compression result codes enabled.

FLOW CONTROL CHARACTER - XON
Type:	Register
Format:	AT [cmds] S22=n [cmds]
Example:	ATS22=20<CR>
Default:	17
Range:	0-127
Unit:	ASCII
Description:	Sets the character used to represent XON.

FLOW CONTROL CHARACTER - XOFF
Type:	Register
Format:	AT [cmds] S23=n [cmds]
Example:	ATS23=20<CR>
Default:	19
Range:	0-127
Unit:	ASCII
Description:	Sets the character used to represent XOFF.

FLOW CONTROL PASSTHROUGH
Type:	Configuration
Format:	AT [cmds] &In [cmds]
Example:	AT &I0 &W<CR>
Description:	Allows modem to act on, then transmit XON/XOFF characters.
Command	Function
� &I0	Software flow control disabled.
&I1	XON/XOFF passthrough enabled.
&I2	XON/XOFF passthrough disabled.
&I3	ENQ/ACK enabled in host mode.
&I4	ENQ/ACK enabled in terminal mode.
&I5	XON/XOFF passthrough disabled in error correction mode.

FLOW CONTROL TYPE
Type:	Configuration
Format:	AT [cmds] &Hn [cmds]
Example:	AT &H0 A<CR>
Description:	Sets type of flow control used by modem.
Command	Function
&H0	Flow control disabled.
� &H1	CTS/RTS flow control enabled.
&H2	XON/XOFF flow control enabled.
&H3	CTS/RTS and XON/XOFF flow control enabled.

HELP SCREENS
Type:	Immediate
Format:	AT <prefix>$
Example:	AT &$<CR>
Description:	Shows command help screens for all commands beginning with the given prefix, or no prefix if none is given.
Command	Function
$	Shows ATx help screen.
&$	Shows AT&x help screen.

INACTIVITY TIMER
Type:	Register
Format:	AT [cmds] S19=n [cmds]
Example:	ATS19=20<CR>
Default:	0
Range:	Unidentified
Unit:	1 minute
Description:	Sets the length of time that the modem does not receive information before it disconnects.

LOCK SERIAL PORT
Type:	Configuration
Format:	AT [cmds] &Bn [cmds]
Example:	AT &N9 &B0<CR>
Description:	Sets operation of serial port speed.
Command	Function
&B0	Serial speed follows connect speed
� &B1	Serial speed locked.
&B2	Serial speed locked in ARQ mode only,

REPORT INFORMATION
Type:	Immediate
Format:	AT [cmds] In [cmds]
Example:	AT I1 O<CR>
Description:	Displays modem properties.
Command	Function
I0	Reports product code.
I1	Reports ROM checksum result.
I2	Reports RAM checksum result.
I3	Reports firmware version.
I4	Reports current command settings.
I5	Reports current NVRAM settings.
I6	Reports current connection�s statistics.
I7	Reports configuration.

TONE DIALING TEST
Type:	Register
Format:	AT [cmds] S16=n [cmds]
Example:	ATS16=139<CR>
Description:	Selects the tone dialing test
Command	Function
� S16=0	Tone dialing test disabled.
S16=2	Tone dialing test enabled.

V.32 AND V.32bis MODULATIONS
Format		AT [cmds] S34=n [cmds]
Example:		ATS34=139<CR>
Default:		0
Range:		0 - 9
Unit:		Bit-mapped
Description:		Controls V.32 and V.32bis modulations.
Bit	Value		Function
0	� 0 1		V.32bis enabled. V.32bis disabled.
1	0		Not used.
2	0		Not used.
3	� 0 1		V.32 modulation disabled. V.32 modulation enabled.

V.32 HANDSHAKE TIME
Type:	Register
Format:	AT [cmds] S28=n [cmds]
Example:	ATS28=20<CR>
Default:	8
Range:	0-255
Unit:	.1 second
Description:	Sets length of V.32 handshake.