CONNECTIONS
Purpose	Location	Purpose	Location
Line out	CN1	DC power	CN4
Line in	CN2	Power switch	SW1
RS-232/422	CN3

SMART/DUMB MODE
Setting	JP1
» Smart mode	Closed
Dumb mode	Open
Note: Manufacturer’s documentation does not specify pin assignments corresponding to dumb/smart mode settings.

DIAGNOSTIC LED(S)
LED	Color	Status	Condition
HS	Red	On	Modem connected at 2400bps
HS	Red	Off	Modem not connected at 2400bps
AA	Red	On	Auto-answer enabled
AA	Red	Off	Auto-answer disabled
AA	Red	Blinking	Phone is ringing
CD	Red	On	Carrier signal detected
CD	Red	Off	Carrier signal not detected
OH	Red	On	Modem is off-hook
OH	Red	Off	Modem is on-hook
RD	Red	On	Modem is receiving data
RD	Red	Off	Modem is not receiving data
SD	Red	On	Modem is transmitting data
SD	Red	Off	Modem is not transmitting data
TR	Red	On	DTR signal is high
TR	Red	Off	DTR signal is low
MR	Red	On	Power is on
MR	Red	Off	Power is off

BIT-MAPPED REGISTER S14
Format		AT [cmds] S14=n [cmds]
Example:		ATS14=138<CR>
Default:		138
Range:		0-190
Unit:		Bit-mapped
Description:		Controls echo, result codes, result code display, smart/dumb mode, dial mode, and answer/originate mode.
Bit	Value		Function
0	0		Not used.
1	0 » 1		Command echo disabled. Command echo enabled.
2	» 0 1		Result codes enabled. Result codes disabled.
3	0 » 1		Display result codes in numeric format. Display result codes in verbose format.
4	» 0 1		Smart mode. Dumb mode
5	» 0 1		Tone dial enabled. Pulse dial enabled.
6	0		Not used.
7	0 » 1		Answer mode enabled. Originate mode enabled.
Note: Bit 4 is not used, in the Internal Super Modem 2400.

BIT-MAPPED REGISTER S21
Format		AT [cmds] S21=n [cmds]
Example:		ATS21=56<CR>
Default:		56
Range:		0 - 189
Unit:		Bit-mapped
Description:		Selects jack type, CTS signal, low DTR action, DCD signal, and the Long Space Disconnect function.
Bit	Value		Function
0	» 0 1		Selects RJ-11, RJ-41S, or RJ45S jack. Selects RJ-12 or RJ-13 jack.
1	0		Not used.
2	» 0 1		CTS follows RTS. CTS forced high.
4, 3	00 01 10 » 11		DTR signal ignored. Modem goes to command mode on low DTR. Modem disconnects on low DTR. Auto-Answer is disabled. Modem is initialized on low DTR.
5	0 » 1		DCD forced high. DCD normal.
6	0		Not used.
7	» 0 1		Long Space Disconnect function disabled. Long Space Disconnect function enabled.
Note: Bit 2 is not used, in the Internal Super Modem 2400.

BIT-MAPPED REGISTER S22
Format		AT [cmds] S22=n [cmds]
Example:		ATS22=5<CR>
Default:		5
Range:		0-126
Unit:		Bit-mapped
Description:		Controls speaker volume and controls, and limits results codes.
Bit	Value		Function
1, 0	01 » 10 11		On volume. Medium level volume. High level volume.
3, 2	00 » 01 10 11		Speaker off. Speaker off on carrier. Speaker always on. Speaker on during handshake.
6, 5, 4	» 000 100 101 110 111		Basic result codes only enabled. Basic and connection speed result codes enabled. Basic and connection speed result codes and dialtone detection enabled. All result codes except dialtone detection enabled. All result codes enabled.
7	» 0 1		39/61ms at 10pps (North America) 33/67ms at 10pps (Europe)

BIT-MAPPED REGISTER S23
Format		AT [cmds] S23=n [cmds]
Example:		ATS23=54<CR>
Default:		54
Range:		0-183
Unit:		Bit-mapped
Description:		Grants/denies remote digital loopback, controls DTE rate and parity, and sets guard tone.
Bit	Value		Function
0	» 0 1		Remote digital loopback denied. Remote digital loopback allowed.
2, 1	00 10 » 11		Sets serial port speed to 0-300bps. Sets serial port speed to 1200bps. Sets serial port speed to 2400bps.
3	0		Not used.
5,4	00 01 10 » 11		Parity even. Space parity. Parity odd. No Parity.
7, 6	» 00 01 10		Guard tone disabled. Guard tone disabled. Guard tone 1800Hz enabled.

BIT-MAPPED REGISTER S27
Format		AT [cmds] S27=n [cmds]
Example:		AT S27=64 <CR>
Default:		64
Range:		0 - 103
Unit:		Bit-mapped
Description:		Selects sync/async mode, Line type, internal clock, and ITU-T/Bell modes.
Bit	Value		Function
1, 0	» 00 01 10 11		Asynchronous mode. Synchronous command mode and synchronous connect mode. Synchronous command mode and synchronous connect mode, DTR dialing enabled. Manual originating a synchronous call.
2	» 0 1		Dial up line. Leased line.
3	0		Not used.
5, 4	» 00 01 10		Internal DTE transmit clock source. External DTE transmit clock source. Slave DTE transmit clock source.
6	0 » 1		CCITT mode. Bell mode.

TEST MODES
Format		AT [cmds] S16=n [cmds]
Example:		ATS16=0<CR>
Default:		0
Range:		0-125
Unit:		Bit-mapped
Description:		Controls loopback tests, analog, digital, remote digital, and self tests.
Bit	Value		Function
0	» 0 1		Local analog loopback not in progress. Local analog loopback in progress.
1	0		Not used.
2	» 0 1		Local digital loopback not in progress. Local digital loopback in progress.
3	» 0 1		Modem not in remote digital loopback. Remote digital loopback in progress.
4	» 0 1		Remote digital loopback not requested. Remote digital loopback requested.
5	» 0 1		Remote digital loopback w/ self-test not in progress. Remote digital loopback w/ self-test in progress.
6	» 0 1		Local analog loopback w/ self-test not in progress. Local analog loopback w/ self-test in progress.