Contents:

Welcome to 56K Information Access

Product Features

Installation for All Operating Systems

Troubleshooting

Technical Reference >

Introduction to Syntax and Procedures

Data Command Set

• Generic Modem Commands
• DTE Interface
• Call Control
• Modulation Control Commands
• Error Control Commands
• Data Compression Commands
• Diagnostic Commands
• V.92 +P Commands
• S Parameters

Result Codes

Glossary

Regulatory Information

Limited Warranty

S-Parameters

The S-Parameters registers denoted with an '*' may be stored in one of the two user profiles by entering the &W command. One of these profiles may be loaded at any time by using the Z command. Registers or register fields quoted as "reserved" are reserved for current or future use by the firmware, or are permanently overridden by PTT limitations. For the latter, control of the equivalent functionality is available with ConfigurACE Call Progress and Blacklisting options.

All bit-mapped registers are read-only. The appropriate AT command which controls the relevant bits in the S-Parameter should be used to change the value.

S - Read/Write S-Parameter

The modem selects an S-Parameter, performs an S-Parameter read or write function, or reports the value of an S-Parameter.

n - Establishes S-Parameter n as the last register accessed.
n=v - Sets S-Parameter n to the value v.
n? - Reports the value of S-Parameter n.

The parameter n can be omitted, in which case the last S-Parameter accessed will be assumed. The S can be omitted for AT= and AT?, in which case the last S-Parameter accessed will be assumed. For example:

ATS7 establishes S7 as the last accessed register.
AT=40 sets the contents of the last register accessed to 40.
ATS=20 sets the contents of the last register accessed to 20.

If the number "n" is outside the range of the S-Parameters available, the modem will return the ERROR message. If the value "v" is outside the range permitted for a given S-Parameter, the modem will return the ERROR message. Input and output are always in decimal format. Note that some S-Parameters are read-only.

In some cases, writing to the S-Parameter will appear to be accepted but the value will not actually be written.

Due to country restrictions, some commands will be accepted, but the value may be limited and replaced by a maximum or minimum value.

Minimum, maximum, and default values for S-Parameters may be altered with ConfigurACE.

FACTORY DEFAULTS

The factory default values are stored in ROM and are loaded into the active configuration at power up or by the ATZ command. In addition, the designated default profile is subsequently loaded, and may change some of the factory default values. The designated default profile can be changed by entering the &Y command where n is one of the two possible user profiles.

The defaults shown are those used by USRobotics in factory profiles zero and one. These may be overwritten by the OEM with ConfigurACE prior to placing the firmware in PROM. Minimum and maximum values may also be imposed by ConfigurACE in response to country PTT requirements.

The default values shown in the table below may vary by modem firmware configuration. Consult the MCU firmware release notes for exact configuration.

The factory default values may be loaded at any time by entering the &Fn command.

S-PARAMETER DEFINITIONS

S0 - Number of Rings to Auto-Answer

S0 sets the number of the rings required before the modem automatically answers a call. Setting this parameter to zero disables auto-answer mode.

Range: 0-255 rings
Default: 0

S1 - Ring Counter

S1 is incremented each time the modem detects a ring signal on the telephone line. S1 is cleared if no rings occur over an eight second interval.

Range: 0-255 rings
Default: 0

S2 - Escape Character

S2 holds the decimal value of the ASCII character used as the escape character. The default value corresponds to an ASCII '+'. A value over 127 disables the escape process, i.e., no escape character will be recognized.

Range: 0-255, ASCII decimal
Default: 43 (+)

S3 - Carriage Return Character

S3 sets the command line and result code terminator character. Pertains to asynchronous operation only.

Range: 0-127, ASCII decimal
Default: 13 (Carriage Return)

S4 - Line Feed Character

S4 sets the character recognized as a line feed. Pertains to asynchronous operation only. The Line Feed control character is output after the Carriage Return control character if verbose result codes are used.

Range: 0-127, ASCII decimal
Default: 10 (Line Feed)

S5 - Backspace Character

S5 sets the character recognized as a backspace. Pertains to asynchronous operation only. The modem will not recognize the Backspace character if it is set to a value that is greater than 32 ASCII. This character can be used to edit a command line. When the echo command is enabled, the modem echoes back to the local DTE the Backspace character, an ASCII space character and a second Backspace character; this means a total of three characters are transmitted each time the modem processes the Backspace character.

Range: 0-32, ASCII decimal
Default: 8 (Backspace)

S6 - Wait Time before Blind Dialing or for Dial Tone

S6 operation is country dependent.

1. Sets the length of time, in seconds, that the modem will wait before starting to dial after going off-hook when blind dialing. This operation, however, may be affected by some ATX options according to country restrictions. The "Wait for Dial Tone" call progress feature (W dial modifier in the dial string) will override the value in register S6. (US models.)
2. Sets the length of time, in seconds, that the modem will wait for dial tone when encountering a "W" dial modifier before returning NO DIAL TONE result code. (W class.)

The modem always pauses for a minimum of 2 seconds, even if the value of S6 is less than 2 seconds.

Range: 2-255 seconds
Default: 2

S7 - Wait Time for Carrier, Silence, or Dial Tone

S7 operation is country dependent.

1. Sets the length of time, in seconds, that the modem will wait for carrier before hanging up. The timer is started when the modem finishes dialing (originate), or 2 seconds after going off-hook (answer). In originate mode, the timer is reset upon detection of answer tone if allowed by country restrictions.
2. Sets the length of time, in seconds, that modem will wait for silence when encountering the @ dial modifier before continuing with the next dial string parameter.
3. Sets the length of time, in seconds, that the modem will wait for dial tone when encountering a "W" dial modifier before continuing with the next dial string parameter. (US models.)
   
   Range: 1-255 seconds
   Default: 50

S8 - Pause Time For Dial Delay

S8 sets the time, in seconds, that the modem must pause when the "," dial modifier is encountered in the dial string.

Range: 2-255 seconds
Default: 2

S9 - Carrier Detect Response Time

S9 is supported for backwards compatibility only. No value can be written. Responds with default value.

Range: 6 tenths of a second
Default: 6 (0.6 second)

S10 - Lost Carrier To Hang Up Delay

S10 sets the length of time, in tenths of a second, that the modem waits before hanging up after a loss of carrier. This allows for a temporary carrier loss without causing the local modem to disconnect. When register S10 is set to 255, the modem functions as if a carrier is always present.

The actual interval the modem waits before disconnecting is the value in register S10 minus the value in register S9. Therefore, the S10 value must be greater than the S9 value or else the modem disconnects before it recognizes the carrier.

Range: 1-255 tenths of a second
Default: 14 (1.4 seconds)

Note: For Call Waiting detection, if the modem is set to US country code and S10 >=16, then the modem will detect the Call Waiting tone and hang-up the line. If S10 <16, the modem will not detect Call Waiting tone.

S11 - DTMF Tone Duration

S11 operation is country dependent.

1. For US models, S11 sets the duration of tones in DTMF dialing (has no effect on pulse dialing).
2. For W-class models, S11 is a country parameter loaded by ConfigurACE.
   
   Range: 50-255 milliseconds
   Default: 95 (95 milliseconds)

S12 - Escape Prompt Delay (EPD)

S12 defines the maximum period, in fiftieths of a second, allowed between receipt of the last character of the three escape character sequence from the DTE and sending of the OK result code to the DTE. If any characters are detected during this time, the OK will not be sent. Sending of the OK result code does not affect entry into command mode. (See 3.1.3.)

Range: 0-255 1/50 of a second
Default: 50 (1 second)

S14 - General Bit Mapped Options Status

S14 indicates the status of command options.

Default: 138 (8Ah) (10001010b)

Bit 0 This bit is ignored.
Bit 1 Command echo (En)
- 0 = Disabled (E0)
- 1 = Enabled (E1) (Default.)
Bit 2 Quiet mode (Qn)
- 0 = Send result codes (Q0) (Default.)
- 1 = Do not send result codes (Q1)
Bit 3 Result codes (Vn)
- 0 = Numeric (V0)
- 1 = Verbose (V1) (Default.) Bit 4 Reserved
Bit 5 Tone (T)/Pulse (P)
- 0 = Tone (T) (Default.)
- 1 = Pulse (P)
Bit 6 Reserved
Bit 7 Originate/Answer
- 0 = Answer
- 1 = Originate (Default.)

S16 - Test Mode Bit Mapped Options Status

S16 indicates the test in progress status.

Default: 0

Bit 0 - Local analog loopback
- 0 = Disabled (Default.)
- 1 = Enabled (&T1)
Bits 1-7 Not used

S19 - Reserved

S19 is supported for backwards compatibility only. No value can be written. Responds with default value.

Range: None
Default: 0

S20 - Reserved

S20 is supported for backwards compatibility only. No value can be written. Responds with default value.

Range: None
Default: 0

S21 - V.24/General Bit Mapped Options Status

S21 indicates the status of command options.

Default: 52 (34h) (00110100b)

Bits 0 - 1 Reserved (0)
Bit 2 CTS behavior (&Rn)
- 0 = CTS tracks RTS (&R0)
- 1 = CTS always on (&R1) (Default.)
Bits 3-4 DTR behavior (&Dn)
- 0 = &D0 selected
- 1 = &D1 selected
- 2 = &D2 selected (Default.)
- 3 = &D3 selected
Bit 5 RLSD (DCD) behavior (&Cn)
- 0 = &C0 selected
- 1 = &C1 selected (Default.)
Bit 6 DSR behavior (&Sn)
- 0 = &S0 selected (Default.)
- 1 = &S1 selected
Bit 7 Long space disconnect (Yn)
- 0 = Y0 (Default.)
- 1 = Y1

S22 - Speaker/Results Bit Mapped Options Status

S22 indicates the status of command options.

Default: 117 (75h) (01110101b)

Bits 0-1 Speaker volume (Ln)
- 0 = Off (L0)
- 1 = Low (L1) (Default.)
- 2 = Medium (L2)
- 3 = High (L3)
Bits 2-3 Speaker control (Mn)
- 0 = Disabled (M0)
- 1 = Off on carrier (M1) (Default.)
- 2 = Always on (M2)
- 3 = On during handshake (M3)
Bits 4-6 Limit result codes (Xn)
- 0 = X0
- 4 = X1
- 5 = X2
- 6 = X3
- 7 = X4 (Default.)
Bit 7 Reserved

S23 - General Bit Mapped Options Status

S23 indicates the status of command options.

Default: 0

Bits 0-6 Not used
Bits 6-7 Guard tone (&Gn)
- 0 = None (&G0) (Default.)
- 1 = None (&G1)
- 2 = 1800 Hz (&G2)

S24 - Sleep Inactivity Timer

S24 sets the length of time, in seconds, that the modem will operate in normal mode with no detected telephone line or DTE line activity before entering low-power sleep mode. The timer is reset upon any DTE line or telephone line activity. If the S24 value is zero, neither DTE line nor telephone inactivity will cause the modem to enter the sleep mode.

Range: 0-255 seconds
Default: 0

S25 - Delay To DTR Off

S25 sets the length of time that the modem will ignore DTR for taking the action specified by &Dn. Its units are seconds for synchronous modes and one hundredths of a second for other modes.

Range: 0-255 (1 second for synchronous modes 1; 0.01 second otherwise)
Default: 5

S26 - RTS to CTS Delay

S26 sets the time delay, in hundredths of a second, before the modem turns CTS ON after detecting an OFF-to-ON transition on RTS when &R0 is commanded. Pertains to synchronous operation only.

Range: 0-255 hundredths of a second
Default: 1

S27 - Bit mapped register

Bit
0 = Reserved
1 = Reserved
2 = V.32 modulation disabled
3 = Reserved
4 = V.23 fallback disabled
5 = V.32bis modulation disabled
6 = Selective Reject disabled
7 = Compatibility Mode - CONNECT 9600

S28 - Bit Mapped Options Status

S28 indicates bit mapped options status.

Default: 0

Bits 0 - 1 Reserved
Bit 2 Reserved (always 0).
Bits 3 - 4 Pulse dialing (&Pn)
- 0 = 39%-61% make/break ratio at 10 pulses per second (&P0) (Default.)
- 1 = 33%-67% make/break ratio at 10 pulses per second (&P1)
- 2 = 39%-61% make/break ratio at 20 pulses per second (&P2)
- 3 = 33%-67% make/break ratio at 20 pulses per second (&P3)
Bit 5-7 Reserved

S29 - Flash Dial Modifier Time

S29 sets the length of time, in units of 10 ms, that the modem will go on-hook when it encounters the flash (!) dial modifier in the dial string. S29 is a country dependent parameter. The S29 value cannot be changed using S29=XX.

Range: 0-255 10 ms intervals
Default: 70 (700 ms) for U.S.

S30 - Disconnect Inactivity Timer

S30 sets the length of time, in tens of seconds, that the modem will stay online before disconnecting when no data is sent or received. In error-correction mode, any data transmitted or received will reset the timer. In other modes, any data transmitted will reset the timer. The timer is inoperative in synchronous mode.

Range: 0-255 tens of seconds (0-2550 seconds)
Default: 0 (disabled)

S31 - Bit Mapped Options Status

S31 indicates bit mapped options status.

Default: 192 (C0h) (11000000b)

Bit 0 Single line connect message enable/disable (\Vn)
- 0 = Messages controlled by S95, Wn and Vn (\V0) (Default.)
- 1 = Single line connect message (\V1)
Bit 1 Reserved (0)
Bits 2-3 Error correction progress messages (Wn)
- 0 = DTE speed only (W0) (Default.)
- 1 = Full reporting (W1)
- 2 = DCE (line) speed only (W2)
Bits 4-5 Caller ID (+VCID)
- 0 = Caller ID disabled (+VCID=0) (Default.)
- 1 = Short (formatted) Caller ID enabled (+VCID=1)
- 2 = Long (unformatted) Caller ID enabled (+VCID=2)
Bits 6-7 Reserved (Default = 11b)

S32 - Bit mapped register

Bit
0 = V.8 CI enabled
1 = V.8 mode disabled
2 = Reserved
3 = V.34 modulation disabled
4 = V.34 limited to 28800
5 = Reserved
6 = V.90 modulation disabled
7 = V.92 modulation disabled

S36 - LAPM Failure Control

Default: 7 (00000111b)

Bits 0-2 This value indicates what should happen upon a LAPM failure. These fallback options are initiated immediately upon connection if S48=128. If an invalid number is entered, the number is accepted into the register, but S36 will act as if the default value has been entered.
- 0 = Modem disconnects.
- 1 = Modem stays on-line and a Direct mode connection is established.
- 2 = Reserved.
- 3 = Modem stays on-line and a Normal mode connection is established.
- 4 = An MNP connection is attempted and if it fails, the modem disconnects.
- 5 = An MNP connection is attempted and if it fails, a Direct mode connection is established.
- 6 = Reserved.
- 7 = An MNP connection is attempted and if it fails, a Normal mode connection is established. (Default.)
Bits 3-7 Reserved

S38 - Delay Before Forced Hang Up

S38 specifies the delay between the modem's receipt of the H command to disconnect (or ON-to-OFF transition of DTR if the modem is programmed to follow the signal), and the disconnect operation. Applicable to error-correction connection only. This parameter can be used to ensure that data in the modem buffer is sent before the modem disconnects.

1. If S38 is set to a value between 0 and 254, the modem will wait that number of seconds for the remote modem to acknowledge all data in the modem buffer before disconnecting. If time expires before all data is sent, the NO CARRIER result code will be issued to indicate that data has been lost. If all data is transmitted prior to time-out, the response to the H0 command will be OK.
2. If S38 is set to 255, the modem does not time-out and continues to attempt to deliver data in the buffer until the connection is lost or the data is delivered.
   
   Range: 0-255 seconds
   Default: 20

S39 - Flow Control Bit Mapped Options Status

Default: 3 (00000011b)

Bits 0-2 Status of command options
- 0 = No flow control
- 3 = RTS/CTS (&K3) (Default.)
- 4 = XON/XOFF (&K4)
- 5 = Transparent XON (&K5)
- 6 = Both methods (&K6)
Bits 3-7 Reserved

S40 - General Bit Mapped Options Status

S40 indicates the status of command options.

Default: 104 (68h) (01101000b)

Bits 0-1 MNP Extended Services (-Kn)
- 0 = Disable extended services (-K0) (Default.)
- 1 = Enable extended services (-K1)
- 2 = Enable extended services (-K2)
Bit 2 Reserved
Bits 3-5 Break Handling (\Kn)
- 0 = \K0
- 1 = \K1
- 2 = \K2
- 3 = \K3
- 4 = \K4
- 5 = \K5 (Default.)
Bits 6-7 Reserved

S46 - Data Compression Control

S46 controls selection of compression. The following actions are executed for the given values:

Range: 136 or 138
Default: 138
S46=136 Execute error correction protocol with no compression.
S46=138 Execute error correction protocol with compression. (Default.)

S48 - V.42 Negotiation Control

The V.42 negotiation process determines the capabilities of the remote modem. However, when the capabilities of the remote modem are known and negotiation is unnecessary, this process can be bypassed if so desired.

Range: 0, 7, or 128 If an invalid number is entered, it is accepted into the S-Parameter, but S48 will act as if 128 has been entered.
Default: 7
S48=0 Disable negotiation; bypass the detection and negotiation phases; and proceed with LAPM.
S48=7 Enable negotiation. (Default.)
S48=128 Disable negotiation; bypass the detection and negotiation phases; and proceed at once with the fallback action specified in S36. Can be used to force MNP.

S86 - Call Failure Reason Code

When the modem issues a NO CARRIER result code, a value is written to S86 Register to help determine the reason for the failed connection. S86 records the first event that contributes to a NO CARRIER message. The code definitions are:

Range: 0-26
Default: 21
S86=0 Normal hangup, no error occurred.
S86=1 Reserved. S86=2 Reserved.
S86=3 Call Waiting caused disconnect.
S86=4 Physical carrier loss.
S86=5 No error correction at the other end.
S86=6 No response to feature negotiation.
S86=7 This modem is async only; the other modem is sync only.
S86=8 No framing technique in common.
S86=9 No protocol in common.
S86=10 Bad response to feature negotiation.
S86=11 No sync information from the remote modem.
S86=12 Normal hangup initiated by the remote modem.
S86=13 Retransmission limit reached.
S86=14 Protocol violation occurred.
S86=15 Lost DTR.
S86=16 Received GSTN cleardown.
S86=17 Inactivity timeout.
S86=18 Speed not supported.
S86=19 Long space disconnect.
S86=20 Key abort disconnect.
S86=21 Clears previous disconnect reason.
S86=22 No connection established.
S86=23 Disconnect after three retrains.
S86=24 Call Waiting tone detected.
S86=25 Extension pickup detected.
S86=26 Remote hangup detected.

S91 - PSTN Transmit Attenuation Level

In non-PCM modes (V.90 or K56flex are PCM modes), S91 sets the transmit attenuation level from 0 to 15 dBm for the PSTN mode, resulting in a transmit level from 0 to -15 dBm. In some countries, the transmit level may not be changed and there are checks to prevent transmit attenuation level change using ConfigurACE.

Range: 0 to 15 dBm (Corresponding to 0 to -15 dBm transmit level.)
Default: 10 (-10 dBm transmit level.)

S92 - Fax Transmit Attenuation Level

S92 sets the transmit attenuation level from 0 to 15 dBm for the fax mode, resulting in a transmit level from 0 to -15 dBm. In some countries, the transmit level may not be changed and there are checks to prevent transmit attenuation level change using ConfigurACE.

Range: 0 to 15 dBm (Corresponding to 0 to -15 dBm transmit level.)
Default: 10 (-10 dBm transmit level.)

S95 - Extended Result Codes Control

A bit set to a 1 in this parameter, in conjunction with the W command, will enable the corresponding extended result code.

The +MR, +ER, and +DR settings also control S95 bits 2, 3, and 5, respectively. The more recent settings of +MR, +ER, and +DR, or host writing of S95 bits 2, 3, and 5, along with the W command setting, determine the corresponding actual result code reporting (see +MR, +ER, DR, and W commands).

Default: 0

Bit 0 CONNECT result code indicates DCE speed instead of DTE speed.
Bit 1 Append/ARQ to CONNECT XXXX result code in error-correction mode (XXXX = rate).
Bit 2 Enable +MCR: XXXX result code (XXXX = modulation) and +MRR: XXXX result code (XXXX = rate). (Also, see +MR.)
Bit 3 Enable +ER: XXXX result code (XXXX = protocol identifier).
Bit 4 Reserved.
Bit 5 Enable +DR: XXXX result code (XXXX = compression type).
Bits 6-7 Reserved.

S210 - V.34 Symbol Rates

The bits in this parameter control V.34 symbols rates and enables/disables V.34 asymmetric rates. This parameter is used for diagnostic purpose only.

Default: 13 (0Dh) (00001101b)

Bits 0-2 Selects the range of allowed V.34 symbol rates.
2 1 - 0 - Symbol Rates (baud)
0 0 - 0 = 2400 only
0 0 - 1 = 2400 only (no 2734)
0 1 - 0 = 2400, 2800
0 1 - 1 = 2400, 2800, 3000
1 0 - 0 = 2400, 2800, 3000, 3200
1 0 - 1 = 2400, 2800, 3000, 3200, 3429 (Default.)
Bit 3 Enable/disable V.34 asymmetric rates.
- 0 = Disable asymmetric rates
- 1 = Enable asymmetric rates (Default.)
Bits 4-7 Reserved.

Examples

S210=13 Enable asymmetric rates with all symbol rates available (Default.).
S210=5 Disable asymmetric rates with all symbol rates available.
S210=8 Enable asymmetric rates with only 2400 baud available.
S210=11 Enable asymmetric rates with 2400 to 3000 baud available.