ATT.TXT Driver File Contents (1414PCV.exe)

******************************************************************************
********            This document is for the FM288T fax/modem -    ***********
************ The type is identified on the top left back of the modem. *******
******************************************************************************
______________________________________________________________________________
Table of Contents - AT&T Chip Set

 1**Extended AT Command Set
 2**AT Command Result Codes
 3**S-Registers
 4**Bit Mapped and S-Registers
 5**Error Correction, Data Compression, and Flow Control
 6**Leased-Line Operation
 7**Fax Operation
 8**Diagnostic Tests
_____________________________________________________________________________
1**Extended AT Command Set**

Data Transmission Commands
AT Commands
A/	Re-execute previous command.
=n	Write n to S-register referenced by Sr, 0  n  255.
?	Read S-register referenced by Sr.
A	Answer.
Bn	Line Modulation Options
	B0	CCITT operation, selects v.21 at 300 b/s or v.22 at 1200 b/s
	B1	Bell operation, selects Bell 103 at 300 b/s or Bell 212A at 
		1200 b/s (default)
	B2	Selects V.23 originate mode receive 1200 bits/s, transmit 75 
		bits/s; answer mode receives 75 bits/s, transmit 1200 bits/s
	B3	Selects V.23 originate mode receive 75 bits/s, transmit 1200
		bits/s; answer mode receives 1200 bits/s, transmit 75 bits/s

Cn	Carrier control Option (dummy command).
	C0	Transmit carrier always off (returns ERROR)
	C1	Normal transmit carrier switching

D	Dial
        0-9     Dial DTMF digits 0 to 9.
        *       Dial the "star" symbol (tone dialing only).
        #       Dial the "pound" symbol (tone dialing only).
        A-D     Dial DTMF digits A, B, C, and D. May be dialed as a tone only
		    Some countries may prohibit sending these digits during 
		    dialing.
        P       Select pulse dialing; affects current and subsequent dialing.
        T	    Select tone dialing; affects current and subsequent dialing.
        R       Reverse dial mode.  Originates call in answer mode. 
        S=n     Dial stored number. Dial the number stored in location 
		    n=(0-3) 
        W       Wait for dial tone. If no dial tone is detected within the
                time specified by S7, the modem aborts the rest of the
                sequence, goes on-hook, and generates an error message.
	  !       Flash: go on-hook for 0.5s then return off-hook.  
        @       Wait for silence. The modem waits for at least 5 seconds of
                silence in the call-progress frequency band before continuing
                with the next dial string parameter. If the modem does not
                detect these 5 seconds of silence before the expiration of
                the call abort timer S7, it terminates the call attempt with
                a NO ANSWER message. If busy detection is enabled, the modem
                may terminate the call with a BUSY result code. If answer
                tone arrives during execution of this parameter, the modem
                handshakes with the remote modem.
        ,       Pause. The modem pauses for a time specified by S8 before
                dialing the following digits. Most often used when dialing an
                outside line through a PBX.
        ;       Return to idle state. Modem returns to command mode after 
		    dialing a number without disconnecting the call.
        ( )     Ignored; can be used to format the dial string. 
        -       Ignored; can be used to format the dial string. 
        <sp>    Spaces are ignored; can be used to format the dial string.
        <i>	    Invalid characters are ignored. 
        

En      Command echo
        E0      Disables command echo. 
        E1      Enables command echo (default). 

Fn      On-Line Echo Command (dummy command)
                This command is used by some modems to determine whether
                characters are echoed to the DTE from the modem when it is in
                the on-line state.  This modem will return an error if F0 is
                sent and OK if F1 is sent to ensure backward compatibility
                with older software programs.
        F0      Returns ERROR.
        F1      On-line echo disabled.

Hn	Switchhook Contro
        H0      (Default.) The modem goes on-hook.
        H1      If on-hook, the modem goes off-hook but will not train.
In	Modem Identification Command
        I0      Product code. "AT&T V.34 + CLASS I FAX/MODEM"
        I1      Reports 3 digit ROM checksum.  Displays the checksum on DTE.
        I2      Performs ROM check.  Reports either "ROM IS OK" or "ERROR".
        I3      Report ROM components. "ROM 27C010"
        I4      Reports modem capabilities. "007040C0040000"

Ln	Speaker volume
        L0      Off or low volume.
        L1      Low volume.
        L2      Medium volume (default).
        L3      High volume.

Mn	Speaker control
        M0      Speaker is always off.
        M1      Speaker is on during call establishment, but goes off when
                carrier is detected (default).
	  M2	    Speaker is always on.
        M3      Speaker is off during dialing and when receiving carrier, but
                on during answering.

Nn	Select Negotiate Handshake
        N0      When originating or answering, handshake only at the 
		    communication rate specified by S register 37 and Bn and 
		    no fallback.
        N1      (default).When originating or answering, start handshake 
		    only at the communication standard specified by S register
		    37 and Bn. During handshake, fallback to a lower speed may 
		    occure except in \N1 mode.
On	Go on-line data mode
        O0      Returns modem to a previously established state.
        O1      Begins an equalizer retrain sequence, then returns to on-line
		    state.
	  O3-14   Forces the modem to a new rate that is user defined. 
		    (New rates are defined in S62) 

P	Enable pulse dialing until a "T" command or dial modifier is received.

Qn	Quiet results codes control
        Q0      Enables result codes to the DTE (default). 
        Q1      Disables result codes to the DTE. 

Sn	This command selects a specific S-register 
        n=0-99

Sn=m	This command writes a value to a specific register.
	  n=0-99
	  m=0-255
Sn?	This command reads a register
	  n=0-99

T	Enables Tone Dialing

Vn	Result code form
        V0      Enables short-form (terse) result codes.
        V1      Enables long-form (verbose) result codes (default). 

Wn	Selects Extended Results Codes
        W0      Upon connection, the modem reports only the DTE speed
                (e.g., CONNECT 9600). Subsequent responses are disabled
                (default).
        W1      Upon connection, the modem reports the DTE speed; enable the 
		    CARRIER, COMPRESION, and PROTOCOL extended results code.
		    Subsequent responses are disabled.
        W2      Upon connection, the modem reports DCE speed(e.g., CONNECT
                2400). Subsequent responses are disabled.
Xn	Extended result codes
        X0      Displays CONNECT or 1 for all speeds.
        X1      Displays connect messages according to ATW and AT\V commands.
                Disables monitoring of busy tones and dials blindly.
        X2      Displays connect messages according to ATW and AT\V commands.
                Disables monitoring of busy tones and waits for dial tone.
        X3      Displays connect messages according to ATW and AT\V commands.
                Enables monitoring of busy tones and dials blindly.
        X4      Displays connect messages according to ATW and AT\V commands.
                Enables monitoring of busy tones;sends all messages. 
		   (Default.)


Yn	Dummy command for backward compatibility
        Y0      Displays OK.
        Y1      Displays OK.

Zn	Soft reset and restore profile
        Z0      Soft reset and restore stored profile 0.
        Z1      Soft reset and restore stored profile 1.

AT& (ampersand) Commands

 
&Bn   Autoretrain
        &B0     Hang up on a poor received signal.
        &B1     (default) Retrain on a poor received signal.  Hang up if 
		    condition persists longer than the threshold set in register S7.      
        &B2     Do not hang up; do not retrain; accept any line. 

&Cn     Data Carrier Detect (DCD) option
        &C0     DCD remains ON at all times.
        &C1     DCD follows the state of the carrier(default).

&Dn	Data Terminal Ready (DTR) option
        &D0     DTR is ignored.
        &D1     DTR drop is interpreted by the modem as if the asynchronous
                escape sequence had been entered. The modem returns to
                asynchronous command mode without disconnecting.
        &D2     DTR drop is interpreted according to the current &Q setting
                as follows: &Q0 through &Q6:DTR drop causes the modem to hang
                up.  Auto-answer is inhibited if DTR is low (default).
        &D3     DTR drop causes the modem to perform a soft reset as if
                the Z command were received. The &Y setting determines which
		    profile is loaded. &Q2, &Q3: DTR drop causes the modem to 
		    hang up. Auto-answer is inhibited.

&F	Restore factory configuration (profile)
        &F      Recall factory settings as active configuration.

&Gn	Select guard tone
        &G0     Disables guard tone (default).
        &G1     Enables 550-Hz guard tone.
        &G2     Enables 1800-Hz guard tone.

&Jn	Dummy command for backward compatibility.
        &J0     Returns OK to DTE.
        &J1     Returns OK to DTE.

&Kn     Select Flow control.
        This command selects the flow control method chip set provides to the
        DTE to prevent the modem's buffer from overflowing with data. A data
        buffer holds the data until teh modem is ready to trasmit it. When
        the data buffer is full, flow control instructs the DTE to stop
        sending to the modem while the modem continues to send characters.
        &K0     Disables flow control.
	  &K1	    Reserved
	  &K2     Reserved
        &K3     Enables RTS/CTS flow control (default). 
        &K4     Enables XON/XOFF flow control.
        &K5     Supports transparent XON/XOFF flow control.

&Ln     Dial Up/Leased line operation
        &L0     Dial-up line operation (default).
        &L1     Leased line operation.

&Mn	Asynchronous/synchronous mode selection
        Determines the DTR operating mode. The modem treats the &M command as
        a subset of the &Q command.
        &M0     Direct asynchronous operation (default). 
        &M1     Synchronous connect mode with asynchronous off-line command
                mode. The value 001b is written to S27 bits 3, 1, and 0
                respectively.
        &M2     Synchronous connect mode with asynchronous off-line command
                mode. The call is originated when DTR goes high, using the
                ATDS=n stored number dial command.
        &M3     Synchronous connect mode. The call is originated manually. 
	  &M3	    Hayes Autosync Mode.

&Pn	Select pulse dial make/break ratio
        &P0     39/61 make/break ratio at 10 pulses per second (default). 
        &P1     33/67 make/break ratio at 10 pulses per second.

&Qn	Synchronous or asynchronous mode.  See command &M.

&Rn	RTS/CTS option
        &R0     In synchronous mode, CTS tracks the state of RTS; the RTS-to-
                CTS delay is defined by S26. In asynchronous mode, CTS acts
                according to V.25 bis handshake (default).
        &R1     In synchronous mode, CTS is always ON (RTS transitions are
                ignored). In asynchronous mode, CTS drops only if required by
                flow control.

&Sn	DSR override
        &S0     DSR remains ON at all times (default).
        &S1     DSR becomes active after answer tone has been detected and
                inactive after carrier has been lost.

&Tn	Test and diagnostics
        &T0     Terminates test in progress and clears S16.
        &T1     Initiates local analog loopback, V.54 Loop 3. Sets S16 bit 0.
                If a connection exists when this command is issued, the modem
                hangs up. The CONNECT rate message is displayed upon the
                start of the test.
        &T2     Returns ERROR.
        &T3     Initiates local digital loopback,V.54 Loop 2. Sets S16 bit 2.
                If no connection exists, ERROR is returned. Sets S16 bit 4
                when the test is in progress.
        &T4     Enables digital loopback acknowledgment for remote request,
                i.e., a remote digital loopback (RDL) request from a remote
                modem is allowed.Sets S23 bit 0. (Default.)
        &T5     Disables digital loopback acknowledgment for remote request,
                i.e., a remote digital loopback (RDL) request from a remote
                modem is denied. Clears S23 bit 0.
        &T6     Requests a remote digital loopback (RDL), V.54 Loop 2,
                without self-test. If no connection exists, ERROR is returned.
                Sets S16 bit 4 when the test is in progress. The CONNECT or
                CARRIER rate message is displayed upon the start of the test.
        &T7     Requests a remote digital loopback (RDL), V.54 Loop 2, with
                self-test. (In self-test, a test pattern is looped back and
                checked by the modem.) If  no connection exists, ERROR is S18
                or the &T0 or H command, the number of detected errors is
                reported to the DTE. Sets S16 bit 5 when the test is in
                progress.
        &T8     Initiates local analog loopback, V.54 Loop 3, with self-test.
                (In self-test, a test pattern is looped back and checked by
                the modem.).If a connection exists, the modem hangs up before
                the test is initiated. When the test is terminated by
                expiration of S18 or the &T0 or H command, the number of
                detected errors is reported to the DTE. Sets S16 bit 6 when
                the test is in progress. This command may not be available in
                some countries due to PTT restrictions.

&Vn	Display current configuration and stored profiles
        &V0     View active file, stored profile 0, and phone numbers.
        &V1     View active file, stored profile 1, and phone numbers.

&Wn	Store current configuration
        &W0     Store the current configuration as profile 0.
        &W1     Store the current configuration as profile 1.

&Xn	Select synchronous timing
        &X0     Internal timing. The modem generates the transmit clock
                signal and applies it to the TXCLK output at the serial
                interface (default).
        &X1     External timing. The local DTE sources the transmit clock
                signal on the XTCLK input of the serial interface. The modem
                applies this clock to the TXCLK output at the serial
                interface.
        &X2     Slave receive timing. The modem derives the transmit clock
                signal from the incoming carrier and applies it to the TXCLK
                output at the serial interface.

&Yn	Designate a default reset profile
        &Y0     The modem uses profile 0.
        &Y1     The modem uses profile 1.

&Zn=x Store telephone number
        n = 0-3.
        x = dial string (256-byte NVRAM).

AT% (percent) Commands

%An	Set Autoreliable fallback character.
        n       Any ASCII value from 1-127.

%Cn	Data compression.
        %C0     No compression.
        %C1     MNP Class 5 compression when communicating with compression
                compatible link on both ends of line (default).

%Gn     Auto fallforward/fallback enable.
        %G0     Disabled (default).
        %G1     Enabled.

AT\ (backslash) Commands

\An 	Sets the maximum block size during connection.
	  \A0	    Max 64 characters.
	  \A1	    Max 128 characters.
	  \A2	    Max 192 characters.
	  \A3	    Max 256 characters (default).

\Bn	Sends a break to the remote modem
	  \B0-\B9 Break length in 100 ms.

\Cn	Determines whether the modem chip set buffers the data it receives
	during link negotiations.
	  \C0	    Does not buffer data (default)
	  \C1	    Buffers data on answering for 4s, until 200 characters
		    have been buffered, and then switches to normal mode 
		    and the buffered characters are passed to the serial Port.
	  |C2	    Does not buffer data on answeringmodem.  Switches to normal
		    mode upon receipt of autoreliable character and passes it 
		    to serial port.

\Gn	Modem-to-modem flow control (XON/XOFF)
        \G0     Disables modem-to-modem XON/XOFF flow control (default). 
        \G1     Enables modem-to-modem XON/XOFF flow control.

\Jn	Enable DTE auto rate adjustment
        \J0     Disable adjustment of DTE speed to match line speed (default).
        \J1     Enable adjustment of DTE speed to match line speed.

\Kn	Break control
        Determines how modem handles a break.
        If the break is received from the DTE while the modem is in data mode
        with V.42 or normal mode:
        \K0	    Enter command mode; no break sent to remote modem.
        \K1     Clear data buffers and send break to remote modem.
        \K2     Same as 0.
        \K3     Send break to remote modem immediately.
        \K4     Same as 0.
        \K5     Send break to remote modem in sequence with transmitted
                data (default).

        If the break is received from the DTE while the modem is in command
        mode:
        \K0     Send Break to remote modem and enter on-line command mode.
        \K1     Send break to remote modem immediately.
        \K2     Same as 0.
        \K3     Same as 2.
        \K4     Same as 0.
        \K5     Same as 2 (default). 

        If the break is received from a remote modem during V.42 or normal
        mode:
        \K0     Clears data buffers and sends break to the DTE.
        \K1     Same as 0.
        \K2     Send a break immediately to remote modem.
        \K3     Same as 2.
        \K4     Send break to remote modem in sequence with data.
        \K5     Same as 4 (default). 

\Nn	Operating mode; protocol options
        \N0     Normal speed-buffered mode; disables error-correction mode.
                (Forces &Q6.)
        \N1     Selects direct mode, equivalent to &M0, &Q0 mode of operation;
                disables error-correction mode. (Forces &Q0.)
        \N2     MNP reliable (error-correction) mode.
        \N3     LAPM mode is attempted first, followed by MNP mode, and
                finally normal mode is selected if both fail (default).
        \N4     LAPM mode is attempted first, followed by MNP mode.  If both
                fail the modem will hang up.

\Qn	DTE flow control options
        \Q0     Disables flow control.
        \Q1     XON/XOFF software flow control.
        \Q2     CTS flow control to DTE.
        \Q3     RTS/CTS hardware flow control (default).

\Tn	Set inactivity timer
        n=0     Disable inactivity timer (default).
        n=1-90  Length in minutes.

\Vn	Protocol result code
        \V0     Disable protocol result code (default).
        \V1     Enable protocol result code.

\Xn	Set XON/XOFF passthrough option
        \X0     Process XON/XOFF per \G and \Q option, if XON/XOFF flow
                control is enabled, donot pass XON/XOFF to the remote modem
                or local DTE (default).
        \X1     Process XON/XOFF per \G and \Q option, always pass XON/XOFF
                to the remote modem or local DTE.

Error Detection and Data Compression Commands

AT- (dash) Commands

-Jn     Set V.42 detection phase
        -J0     Disables the V.42 detection phase.
        -J1     Enables the V.42 detection phase (default).

-V      Display firmware version number

AT" (quote) Commands

"Hn	V.42bis compression control
        "H0     Disable V.42bis.
        "H1     Disable V.42bis only when transmitting data.
        "H2     Disable V.42bis only when receiving data.
        "H3     Disable V.42bis for both send and receive (default).

"Nn	V.42bis dictionary size
        "N0     512 bytes.
        "N1     1024 bytes.
        "N2     1536 bytes (default).

"On	Select V.42bis maximum string length
        n=6-64  Default =32.

AT)C 	(Close Parenthesis) Commands

)Cn	Cellular Activation Command
	  )C0	    No Cellular Support (default)
	  )C1	    AT&T 3730
	  )C2	    Motorola
	  )C3	    NEC
	  )C4	    Fujitsu

______________________________________________________________________________
2**AT Command Result Codes**

The modem responds to commands from the DTE and to activity on the line by
signaling to the DTE in the form of result codes. Display of these messages
is controlled by the Qn command. Q0 (the default) enables result codes.
Q1 disables all result codes; no messages are returned to the DTE.

Two forms of each result code are available: the long form, a "verbose"
English-like response, and the short form, a “terse” numeric response.
The long-form code is preceded and terminated by a carriage return-line feed
sequence; it is enabled by V1 (the default). The short form is terminated by
a carriage return only, and there is no preceding sequence. It is enabled by
V0.
The Xn command controls monitoring of busy tone and dial tone and reporting
of DTE speed and line speed. Table B.1 shows how the value of n in this
command affects result code reporting. An X indicates that the message is
generated for that value of n. If the entry is blank, no message is generated
for that value of n. For certain messages and values of n, a less explicit
result code is substituted for the one listed; a numerical entry indicates
the short form of this substitute message.

Table B.1. Result Codes
                                n in ATXn                                        
Short (Terse)	Long (Verbose)	0	1	2	3	4
00              OK              x       x       x       x       x
01              CONNECT         x       x       x       x       x
02              RING            x       x       x       x       x
03              NO CARRIER      x       x       x       x       x
04              ERROR           x       x       x       x       x
05              CONNECT 1200    01      x       x       x       x
06              NO DIALTONE     03      03      x       x       x
07              BUSY            03      03      03      x       x
08              NO ANSWER       x       x       x       x       x
10              CONNECT 2400    01      x       x       x       x
11              CONNECT 4800    01      x       x       x       x
12              CONNECT 9600    01      x       x       x       x
13              CONNECT 14400   01      x       x       x       x
14              CONNECT 19200   01      x       x       x       x
15              CONNECT 16800   01      x       x       x       x
24              CONNECT 7200    01      x       x       x       x
25              CONNECT 12000   01      x       x       x       x
26              CONNECT 1200/75 01      x       x       x       x
27              CONNECT 75/1200 01      x       x       x       x
28              CONNECT 38400   01      x       x       x       x
29              CONNECT 21600   01      x       x       x       x
30              CONNECT 24000   01      x       x       x       x
31              CONNECT 26400   01      x       x       x       x
32              CONNECT 28800   01      x       x       x       x
34              CONNECT 31200   01      x       x       x       x
35              CONNECT 33600   01      x       x       x       x
33              CONNECT 115200  01      x       x       x       x
40              CARRIER 300                                     x
42              CARRIER 75/1200                                 x
43              CARRIER 1200/75                                 x
46              CARRIER 1200                                    x
47              CARRIER 2400                                    x
48              CARRIER 4800                                    x
49              CARRIER 7200                                    x
50              CARRIER 9600                                    x
51              CARRIER 12000                                   x
52              CARRIER 14400                                   x
53              CARRIER 16800                                   x
54              CARRIER 19200                                   x
55              CARRIER 21600                                   x
56              CARRIER 24000                                   x
57              CARRIER 26400                                   x
58              CARRIER 28800                                   x
66              COMPRESSION: MNP 5                              x
67              COMPRESSION: V.42bis                            x
69              COMPRESSION: NONE                               x
70              PROTOCOL: NONE                                  x
77              PROTOCOL: LAP-M                                 x
80              PROTOCOL: MNP                                   x
81              PROTOCOL: MNP 2                                 x
82              PROTOCOL: MNP 3                                 x
83              PROTOCOL: MNP 2, 4                              x
84              PROTOCOL: MNP 3, 4                              x

Result Codes
	00	OK
Acknowledges execution of a command line.
	01	CONNECT

Note that this result code does not report speed.

The modem sends it upon connecting in any of the following cases:
*	The line speed is 300 b/s and the modem has been instructed to report
        the line speed to the DTE upon connecting.
*       The DTE speed is 300 b/s and the modem has been instructed to report
        the DTE speed to the DTE upon connecting.
*	The range of result code responses is restricted by the Xn command so
        that no speed reporting is allowed.
	02	RING

The modem detects incoming ringing on the line. What qualifies as a ring
signal is determined by country-dependent parameters.
	03	NO CARRIER

The modem sends this result code when attempting to establish a call if
either:
*	Ringback is detected and later ceases but no carrier is detected
        within the period of time determined by register S7.
*	No ringback is detected within the period of time determined by
        register S7.

This result code is also used when the modem auto-disconnects due to loss of
carrier.  Under X0, if busy tone detection is enforced, this result code is
used as a response to the detection of busy or circuit busy.  Under X0, if
dial tone detection is enforced or selected, this result code is used to
indicate that dial tone has not been detected.
	04	ERROR

Indicates that the command line contains a syntax error, a command does not
exist, a parameter is outside the permitted range, or the modem is otherwise
unable to execute the command.
Under X0, X1, X2, and X3, this result is used instead of DELAYED and
BLACKLISTED.
	05	CONNECT 1200

For X1, X2, X3, and X4, the modem sends this result code upon connecting if
either:
*	The line speed is 1200 b/s and the modem has been instructed to
        report the line speed to the DTE upon connecting.
*	The DTE speed is 1200 b/s and the modem has been instructed to report
        the DTE speed to the DTE upon connecting. See also the W command.
	06	NO DIALTONE

For X2 and X4, the modem sends this result code if it has been instructed to
wait for dial tone during dialing but none is received.
	07	BUSY

For X3 and X4, if busy tone detection is enforced, the modem sends this
result code when attempting to originate a call if busy signal is detected
on the line.
	08	NO ANSWER
The modem sends this result code when attempting to originate a call if a
continuous ringback signal is detected on the line until the expiration of
the timer S7.
	10	CONNECT 2400

For X1, X2, X3, and X4, the modem sends this result code if either:
*	The line speed is 2400 b/s and the modem has been instructed to
        report the line speed to the DTE upon connecting.
*	The DTE speed is 2400 b/s and the modem has been instructed to
        report the DTE speed to the DTE upon connecting.
	11	CONNECT 4800

For X1, X2, X3, and X4, the modem sends this result code when the DTE speed
is 4800 b/s and the modem has been instructed to report the DTE speed upon
connecting.
	12	CONNECT 9600

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 9600 b/s and the modem has been instructed to report the DTE
speed to the DTE upon connecting.
	13	CONNECT 14400

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 14400 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	14	CONNECT 19200

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 19200 b/s and the modem has been instructed to report the DTE
speed to the DTE upon connecting.
	15	CONNECT 16800

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 16800 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	18	CONNECT 57600

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 57600 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	24	CONNECT 7200

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 7200 b/s and the modem has been instructed to report the DTE
speed to the DTE upon connecting.
	25	CONNECT 12000

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 12000 b/s and the modem has been instructed to report the DTE
speed to the DTE upon connecting.
	26	CONNECT 1200/75

For X1, X2, X3, and X4, the modem returns this result code upon establishing
a V.23 answer connection when the modem has been instructed to report the DCE
speed upon connection.
	27	CONNECT 75/1200

For X1, X2, X3, and X4, the modem returns this result code upon establishing
a V.23 answer connection when the modem has been instructed to report the DCE
speed upon connection.
	28	CONNECT 38400

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 38400 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	29	CONNECT 21600

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 21600 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	30	CONNECT 24000

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 24000 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	31	CONNECT 26400

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 26400 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	32	CONNECT 28800

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 28800 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	33	CONNECT 115200

For X1, X2, X3, and X4, the modem sends this result code upon connecting when
the DTE speed is 115200 b/s and the modem has been instructed to report the
DTE speed to the DTE upon connecting.
	40	CARRIER 300

Either a V.21 or Bell 103 carrier has been detected on the line and carrier
reporting has been enabled.
	42	CARRIER 75/1200

The V.23 backward channel carrier has been detected on the line and carrier
reporting has been enabled.
	43	CARRIER 1200/75

The V.23 backward channel carrier has been detected on the line and carrier
reporting has been enabled.
	46	CARRIER 1200

Either the high or low channel carrier in either V.22 or Bell 212 mode has
been detected on the line and carrier reporting has been enabled.
	47	CARRIER 2400

Either the high or low channel carrier in V.22 bis mode has been detected on
the line, and carrier reporting has been enabled.
	48	CARRIER 4800

The 4800 b/s data rate in V.32 bis or V.32 mode has been detected on the
line, and carrier reporting has been enabled.
	49	CARRIER 7200

The 7200 b/s data rate in V.32 bis mode has been detected on the line, and
carrier reporting has been enabled.
	50	CARRIER 9600

The 9600 b/s data rate in V.32 bis or V.32 mode has been detected on the
line, and carrier reporting has been enabled.
	51	CARRIER 12000

The 12000 b/s data rate in V.32 bis mode has been detected on the line, and
carrier reporting has been enabled.
	52	CARRIER 14400

The 14400 b/s data rate in V.32 bis or V.34 mode has been detected on the
line, and carrier reporting has been enabled.
	53	CARRIER 16800

The 16800 b/s data rate in V.34 mode has been detected on the line, and
carrier reporting has been enabled.
	54	CARRIER 19200

The 19200 b/s data rate in V.34 mode has been detected on the line, and
carrier reporting has been enabled.
	55	CARRIER 21600

The 21600 b/s data rate in V.34 mode has been detected on the line, and
carrier reporting has been enabled.
	56	CARRIER 24000

The 24000 b/s data rate in V.34 mode has been detected on the line, and
carrier reporting has been enabled.
	57	CARRIER 26400

The 26400 b/s data rate in V.34 mode has been detected on the line, and
carrier reporting has been enabled.
	58	CARRIER 28800

The 28800 b/s data rate in V.34 mode has been detected on the line, and
carrier reporting has been enabled.
	66	COMPRESSION: MNP 5

The modem has connected in MNP Class 5 mode and COMPRESSION message reporting
has been enabled.
	67	COMPRESSION: V.42bis

The modem has connected in V.42bis mode and COMPRESSION message reporting
has been enabled.
	69	COMPRESSION: NONE

The modem has connected without data compression and COMPRESSION message
reporting has been enabled.
	70	PROTOCOL: NONE

The modem has connected without any form of error correction, and the
PROTOCOL message reporting has been enabled.
	71	PROTOCOL: LAPM

The modem has connected in the V.42 LAPM mode of error correction, and
PROTOCOL message reporting has been enabled.
	80	PROTOCOL: MNP

The modem has connected in the MNP mode of error correction, and PROTOCOL
message reporting has been enabled.
	81	PROTOCOL: MNP 2

The modem has connected in the MNP 2 mode of error correction, and PROTOCOL
message reporting has been enabled.
	82	PROTOCOL: MNP 3

The modem has connected in the MNP 3 mode of error correction, and PROTOCOL
message reporting has been enabled.
	83	PROTOCOL: MNP 2, 4

The modem has connected in the MNP 2 and 4 mode of error correction, and
PROTOCOL message reporting has been enabled.
	84	PROTOCOL: MNP 3, 4

The modem has connected in the MNP 3 and 4 mode of error correction, and
PROTOCOL message reporting has been enabled.
______________________________________________________________________________
3**S-Registers**

Hayes-compatible modems store most of their configuration information in
8-bit status registers, or S-registers. For instance, S-register 7 (S7 for
short) determines the length of time the modem waits for carrier before going
back on-hook. You can modify many features of the modem's operation by writing
directly to these registers, using AT commands provided for this purpose.

NOTE: Many AT commands that do not expressly invoke S-registers nonetheless
      write to them. For instance, the Fn command, which selects line
      modulation, writes to S31, and the &Tn test commands write to S16. For
      further examples, see Appendix A.

Table 6.1 shows a summary of your modem's S-registers. Appendix C contains a
detailed description of bit-mapped and coded S-registers.

S-registers are volatile and are not preserved after a power-off or reset.
However, the contents of the registers marked * in Table 6.1 can be saved
permanently in nonvolatile RAM as part of a configuration profile, using the
&Wn command. The S-register values of factory configuration profiles are
stored permanently in the modem's ROM.

You can also configure most communications programs to issue a series of AT
commands, including those that write to S-registers, automatically as part
of a macro or command string associated with specified operations.

Writing to S-Registers

The command to write the value n to S-register r is

        Atr=n  <ENTER>

Since the S-registers hold 8 bits, n must be an integer from 0 to 255.
Although for many S-registers the value of the separate bits is meaningful,
you cannot write directly to individual bits, and you must always enter
values as decimal numbers.

Table 6.1. S-Register Summary
*Can be saved as part of a configuration profile.
No.     Function                        Range           Units   Default
 *0     Rings to auto-answer            0-255           rings   0
  1     Ring counter                    0-255           rings   0
 *2     Escape character                0-255           ASCII   43
  3     Carriage-return character       0-127           ASCII   13
  4     Line-feed character             0-127           ASCII   10
  5     Backspace character             0-255           ASCII   8
 *6     Wait time for dial tone         2-255           s       2
 *7     Wait time for carrier           1-255           s       60
 *8     Pause for dial delay modifier   0-255           s       2
 *9     Carrier detect response time    1-255           0.1 s   6
*10     Carrier loss disconnect time    1-255           0.1 s   14
*11     DTMF tone duration              50-255          0.001 s 95
*12     Escape code guard time          0-255           0.02 s  50
*14     General bit-mapped options      bit specific    ASCII   138
 16     Test mode bit-mapped options    bit specific    _       0
*18     Test timer                      0-255           s       0
 19     AutoSync Protocol Support Mode  bit specific    ASCII   26
 20     AutoSync HDLC Address           bit specific    ASCII   255
*21     V.21/general bit-mapped options bit specific    _       48
*22     General bit-mapped options      bit specific    _       118
*23     General bit-mapped options      bit specific    _       15
 25     Delay to DTR off                0-255           0.02 s  5
 26     RTS-to-CTS delay                0-255           0.01 s  1
*27     General bit-mapped options      bit specific    ASCII   64
 30     Disconnect inactivity timer     0-255           60 s    0
*32     General bit-mapped options      bit specific    _       15
*37     Line connection speed           0-19            _       0
*40     General bit-mapped options      bit specific    ASCII   77
*41     Connect Message Display         0-2             ASCII   0
 42     V.32 Retrain Operation          0-2             ASCII   1
 43     Auto Fallback Character for MNP 1-127           ASCII   13
        Negotiation
 44     General bit-mapped options      bit specific    _       7
*46     Automatic Sleep Timer           0-255           100 ms  255 (disabled)
 47     Forced Sleep Timer  (PCMCIA)    0-255           100 ms  255 (disabled)
        with Powerdown Mode
 48     Set Autoreliable Buffer (\Cn)   0-2             ASCII   0
 49     Set Maximum Block Size          63-255          ASCII   255
 50     Data/Fax Mode                   0-1             ASCII   0
 51     Data/Fax DTE Flow Control       bit specific    ASCII   3
 52     Break Control Option            0-5             ASCII   5
 53     Modem Operating Mode (\Nn)      0-4             ASCII   3
 54     General bit-mapped options      0-7             ASCII   0
 57     V.42bis Dictionary Size         0-2             ASCII   2
 58     BTLZ String Length              6-64            ASCII   32
 59     MNP Bit-mapped Options          0-1             ASCII   1
 62     DTE Rate Status                 0-17            ASCII   16
 65     Round Trip Delay                _               100 ms  0
 72     DTE Speed Select During Data    0-18            ASCII   0
        Transfer
 98     Power-up Profile Number         _               ASCII   0
 99     EEPROM Checksum                 _               ASCII   0

*Can be saved as part of a configuration profile.

For example, S0 determines the number of rings before the modem auto-answers.
The default is 0. To change the number of rings to 1, give the command

        ATS0=1  <ENTER>

S7 determines the time that the modem waits for carrier. The default is 50,
in units of seconds. To change this value to 60 seconds, give the command

        ATS7=60 <ENTER>

Pointing to a Default Register

The command ATSr points to S-register r as the default register. When this
has been done, AT=n writes the value n to S-register r.

The command to change the number of rings before auto-answering to 1 could
therefore also be given as

        ATS0  <ENTER>
        AT=1  <ENTER>

Reading S-Registers

The command

        ATSr? <ENTER>

reports the value of S-register r. For instance:

        ATS0?<ENTER>
        000
        OK

reads the value of S0. Like other AT commands, multiple read commands can be
given together:

        ATS3?S5?<ENTER>
        013
        008
        OK
______________________________________________________________________________
4**Bit Mapped and S-Registers**

This appendix describes the options coded in bit-mapped S-registers,
and certain other S-registers whose contents does not represent a measurement
or a character. For a summary of all S-registers, including those not listed
here, see Table 6.1.

S14	General bit-mapped options
	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     General bit-mapped test options
                Indicates the test in progress status. 
                Default: 0.
        Bit 0   Local analog loopback
                0 = Disabled (default)
                1 = Enabled (&T1)
        Bit 1   Not used
        Bit 2   Local digital loopback
                0 = Disabled (default)
                1 = Enabled (&T3)
        Bit 3   Remote digital loopback (RDL) status
                0 = Modem not in RDL
                1 = RDL in progress
        Bit 4   RDL requested (AT&T6)
                0 = RDL not requested (default)
                1 = RDL requested (&T6)
        Bit 5   RDL with self-test
                0 = Disabled (default)
                1 = Enabled (&T7)
        Bit 6   Local analog loopback (LAL) with self-test
                0 = Disabled (default)
                1 = Enabled (&T8)
        Bit 7   Not used

S19	AutoSync Protocol Support Mode
                 Default: 26.
        Bit 0   Reserved.
        Bit 1   Protocol selection
                0 = Bisync protocol
                1 = HDLC protocol (default)
        Bit 2   Address detector
                0 = Disabled (default)
                1 = Enabled
        Bit 3   NRZI or NRZ bit coding
                0 = NRZI bit coding
                1 = NRZ bit coding (default)
        Bit 4   Select idle
                0 = Mark idle
                1 = Flag idle (default.)
        Bit 5   Reserved
        Bit 6   Reserved
        Bit 7   Reserved

S21	V.21/general bit-mapped options
                Indicates the status of command options.
                Default: 48.
        Bit 0   Reserved
        Bit 1   Reserved
        Bit 2   CTS behavior (&Rn)
                0 = CTS tracks RTS (&R0) (default)
                1 = CTS always on (&R1)
        Bit 3,4 DTR behavior (&Dn)
                0 = &D0 ignore
                1 = &D1 return to command mode
                2 = &D2 disconnect (default)
                3 = &D3 reset modem
        Bit 5   RLSD (DCD) behavior (&Cn)
                0 = &C0 DCD is always on
                1 = &C1 DCD is on after connect (default).
        Bit 6   DSR behavior (&Sn)
                0 = &S0 DSR is always on (default)
                1 = &S1 DSR is on after connect
        Bit 7   Reserved

S22	Speaker/results bit-mapped options
                Indicates the status of command options.
                Default: 118
        Bit 0,1 Speaker volume (Ln)
                0 = Off (L0)
                1 = Low (L1) (default)
                2 = Medium (L2)
                3 = High (L3)
        Bit 2,3 Speaker control (Mn)
                0 = Disabled (M0)
                1 = Off on carrier (M1) (default)
                2 = Always on (M2)
                3 = On during handshake (M3)
        Bit 4,5,6       Limit result codes (Xn)
                0=X0, 
                4=X1, 
                5=X2, 
                6=X3, 
                7=X4 (default)
        Bit 7   Make break ratio (&Pn)
                0 = &P0 is selected (default)
                1 = &P1 is selected

S23     General bit-mapped options
                Indicates the status of command options. 
                Default: 15
                Bit 0   Grant remote digital loopback (RDL)
                0 = RDL not allowed (&T5)
                1 = RDL allowed (&T4) (default)
        Bit 1,2,3       Reserved
        Bit 4,5 Word length
                0 = even parity (default)
                1 = space parity
                2 = odd parity
                3 = mark parity
        Bit 6,7 Guard tone (&Gn)
                0 = None (&G0) (default)
                1 = 550 Hz (&G1)
                2 = 1800 Hz (&G2)

S27	Bit-mapped options
                Indicates the status of command options. 
                Default: 64
        Bit 0,1,3       Synchronous/asynchronous selection (&Mn/&Qn)
                0 = &M0 or &Q0 (default)
                1 = &M1 or &Q1
                2 = &M2 or &Q2
                3 = &M3 or &Q3
                4 = &M4 or &Q4
        Bit 2   Leased-line control (&Ln)
                0 = Dial-up line (&L0) (default)
                1 = Leased line (&L1)
        Bit 4,5 Internal clock select (&Xn)
                0 = Internal clock (&X0) (default)
                1 = External clock (&X1)
                2 = Slave clock (&X2)
        Bit 6   CCITT/Bell mode select (Bn)
                0 = CCITT mode (B0)
                1 = Bell mode (B1) (default)
        Bit 7   Reserved

S31	Bit-mapped options
                   Default: 2 (00000010b). 
        Bit 0   Reserved
        Bit 1   Controls auto line-speed detection (Nn)
                0 = Disabled (N0)
                1 = Enabled (N1) (default)
        Bit 2,3 Controls error correction progress messages (Wn)
                0 = DTE speed only (W0) (default)
                1 = Full reporting (W1)
                2 = DCE speed only (W2)
        Bit 4-7 Reserved


S37     Desired DCE Speed

        Default = 000

        0       = Atttempt to connect at the last AT speed
        3       = Attempt a 300 bits/s connection
        5       = Attempt a 1200 bits/s connection
        6       = Attempt a 2400 bits/s connection
        7       = Attempt a 4800 bits/s connection
        8       = Attempt a 7200 bits/s connection
        9       = Attempt a 9600 bits/s connection
        10      = Attempt a 12000 bits/s connection
        11      = Attempt a 14400 bits/s connection
        12      = Attempt a 16800 bits/s connection
        13      = Attempt a 19200 bits/s connection
        14      = Attempt a 21600 bits/s connection
        15      = Attempt a 24000 bits/s connection
        16      = Attempt a 26400 bits/s connection
        17      = Attempt a 28800 bits/s connection
        18      = Attempt a 31200 bits/s connection
        19      = Attempt a 33600 bits/s connection

S40	General bit-mapped options
                Indicates the status of command options. 
                Default: 77
        Bit 0   Automode select (Nn)
                0 = Disabled (N0)
                1 = Enabled (N1) (default)
        Bit 1-5 Reserved
        Bit 6   V.42 detection phase (-Jn)
                0 = Disabled (-J0) (default)
                1 = Enabled (-J1)
        Bit 7   Reserved

S44	Data compression control
                Controls selection of compression. 
                Default: 7
        Bit 0   V.42bis status
                0 = Disabled
                1 = Enabled (default)
        Bit 1,2 V.42bis selection (“Hn)
                0 = "H0 is selected
                1 = "H1 is selected
                2 = "H2 is selected
                3 = "H3 is selected (default)
        Bit 3   Reserved
        Bit 4   Auto fallback/fallforeward selection (%Gn)
                0 = %G0 is selected (default)
                1 = %G1 is selected
        Bit 5-7 Reserved

S51	Data/Fax DTE flow control selection
                Controls DTE flow control. 
                Default: 3
        Bit 0-1 (&Kn, \Qn)
                0 = &K0, \Q0 are selected
                1 = &K1, \Q1 are selected
                2 = &K2, \Q2 are selected
                3 = &K3, \Q3 are selected
        Bit 2-3 Reserved
        Bit 4   XON/XOFF flow control (\Gn)
                0 = \G0 is selected (default)
                1 = \G1 is selected
        Bit 5   DTE/DCE rate (\Jn)
                0 = \J0 is selected (default)
                1 = \J1 is selected
        Bit 6, 7        XON/XOFF pass-through control (\Xn)
                0 = \X0 is selected (default)
                1 = \X1 is selected

______________________________________________________________________________
5**Error Correction, Data Compression, and Flow Control**

Your modem is compatible with the latest standards for error correction and
data compression. This chapter explains basic concepts of error correction,
data compression, and flow control.

Error Correction

Your modem supports the CCITT V.42 standard for error correction, including
LAPM (link access procedure for modems) and MNP 4.

In ordinary asynchronous transmission, each eight-bit sequence of data is
framed by a start bit and a stop bit. In an error-correction protocol, the
transmitting modem strips off the start and stop bits and divides the data
into larger blocks. (The size of the blocks can vary according to the amount
of data and the quality of the connection, and can be as great as 256 bytes.)
For each block it calculates a polynomial checksum, and transmits both the
block and the checksum synchronously.

The receiving modem must also be an error-correcting modem. It recalculates
the checksum and compares it with the value it received. If they match, the
block is considered good; if they do not match, the receiving modem asks for
the block to be retransmitted. The chance that the checksum will accidentally
match a corrupted block is extremely small_so small that in practice the
transmission can be considered 100-percent error-free.

The most reliable and efficient error-control protocol is CCITT V.42, but
your modem can also use MNP (Microcom Networking Protocol) Level 4, or it
can fall back to MNP 4 or to a non-error-corrected transmission. The error-
control mode is selected by the \N command.

Normal Mode

Normal, asynchronous non-error-correcting mode is used to communicate with
non-error-corrected modems. It is selected by \N0. Auto-reliable mode also
falls back to this mode if error correction is not possible.

Normal mode includes speed buffering, so the local DTE-to-modem speed and the
modem-to-modem line speed can differ. (This is desirable to ensure efficient
data transmission, as discussed under "Flow Control" later in this chapter.)

Direct Mode

Direct mode is similar to normal mode, except that no speed buffering takes
place. DTE speed and line speed must therefore be the same. This mode is
selected by \N1.

Reliable Mode

"Reliable" means an error-correcting mode. In this mode, selected by \N2,
the originating modem first attempts a V.42 LAPM connection (by looking for
the LAPM character during modem handshaking). If the attempt fails, because
the answering modem does not support V.42 or is set for the wrong mode, or
because the line quality is extremely bad, it falls back to an MNP connection
(again by looking for MNP characters).

If the MNP connection also fails (for similar reasons), the originating modem
hangs up. You should therefore use this mode only when error correction is
essential and you are certain that the remote modem supports V.42 or MNP.
Otherwise auto-reliable mode is a better choice.

Auto-Reliable Mode

Auto-reliable mode is identical to reliable mode, except that if the modem
fails to make a reliable connection it falls back to normal speed-buffered
mode. For most users, this is the most flexible and convenient mode. It is
selected by \N3, and is the default error-correcting mode.

Mode

The originating modem attempts to negotiate a V.42 LAPM error-correction
connection. If it fails, it hangs up without falling back to MNP or to normal
mode. This mode is selected by \N4. Like reliable mode, this mode should be
used only when error correction is essential and you are certain that the
remote modem supports V.42.

MNP Mode

The originating modem attempts to negotiate an MNP error-correction
connection. If it fails, it hangs up without falling back to normal mode.
This mode is selected by \N5. Like reliable mode, this mode should be used
only when error correction is essential and you are certain that the remote
modem supports MNP.

Software Error-Correction Protocols

V.42 and MNP error correction are performed by the modem hardware and
firmware. Since data integrity is essential for executable files, most file
transfer protocols, such as XMODEM, used with communications software also
incorporate error-correcting features. These protocols operate similarly to
V.42 and MNP, except that the block length is usually shorter and the
checksum may not be so robust.

When used with an error-correcting modem, software error correction is
redundant and adds overhead, reducing the efficiency of the transfer. On
connections where hardware performs the error correction, you may want to
use a non-error-correcting file transfer protocol such as YMODEM-G or ZMODEM.
The ZMODEM protocol offers other desirable features, such as resumption of an
interrupted file transfer, and imposes only a small penalty for error
correction; it may be a good choice when you cannot be sure of achieving a
hardware-corrected connection.

Data Compression

Many forms of data, such as text, word-processing files, spreadsheet. or
database files, are highly redundant_that is, they contain repeated
characters, or sequences of characters that recur frequently. By removing
the redundancy, such data can be encoded in a shorter form for transmission
over a telephone line and then reconstructed at the remote site, effectively
raising the data throughput of the connection. Like error correction,
hardware data compression must be supported by modems at both ends of the
link.

Executable files usually contain much less redundancy and benefit less from
compression techniques. Files that have already been compressed by an
archiving program, such as PKZIP for DOS or StuffIt on the Macintosh, allow
little or no further compression. Files on computer bulletin boards and on-
line services are often stored in this compressed form.

Your modem supports two data compression standards, V.42 bis and MNP 5.
V.42 bis generally achieves greater compression, and has an additional
advantage over MNP 5: it does not attempt to compress already-compressed
files. MNP 5 tries to compress all files; if the file is already compressed,
this attempt adds processing overhead, and in some cases actually increases
the length of the file (because the protocol must add header information).

Data compression requires simultaneous error correction, since corruption of
even one bit could destroy an entire block of compressed data. V.42 bis data
compression can be used only in conjunction with V.42 error correction.
MNP 5 error compression can be used only in conjunction with MNP 4 error
correction.

Data compression is controlled through the %C command. The default, %C1, 
enables only MNP 5, %C0 disables data compression altogether.

Flow Control

During a data transfer, the two modems at the ends of the connection are
constantly exchanging data. A personal computer used as a DTE, on the other
hand, may also be reading from or writing to disk, and its microprocessor
has many other tasks to perform simultaneously. The speed with which it can
send data to or receive data from the modem therefore varies.

Obtaining Maximum Throughput

If the maximum data transfer rate between DTE and modem (the serial port
speed or DTE speed) is set to the same value as the data transfer rate
between the local modem and the remote modem (the modem speed or line speed),
there will be times when the DTE is unable to send data to or receive data
from the modem as fast as the modem can process it. The modem therefore fails
to achieve its rated throughput. Since your modem can transmit uncompressed
data as fast as 28,800 b/s, for maximum throughput you should set your DTE
speed (usually controlled by the communications software) to 38,400 b/s (or
higher if you are using data compression).

In its default configuration, your modem permits DTE speed and line speed to
differ (\J0). To force the DTE speed to match the line speed, use \J1.

Data Buffers

Of course, if the DTE speed is higher than the line speed, the DTE may send
data to the modem faster than the modem can process it. To deal with this
situation, the modem maintains transmit data buffers in RAM that temporarily
store the extra characters. (The data buffers are also used for error
correction and data compression.)

At any DTE speed, there may be times when the modem sends data to the DTE
faster than the DTE can accept it (for instance, if the DTE is busy writing
to disk). The 16550 UART chip, found in many personal computers, buffers data
received on the serial port, which helps to make high-speed downloads
reliable; this chip is desirable for high-speed data communications.
Communications software may also maintain its own data buffers.

No matter how large a buffer is, however, it can overflow, and if that
happens data is lost. The DTE and the modem must therefore have some way to
stop the flow of data before the buffers overflow. There are two types of
flow control: hardware and software.

NOTE: Modem-to-modem flow control is handled by either the hardware error-
correction protocol or the file transfer protocol.

Hardware Flow Control

Hardware flow control uses the RS-232 RTS (Ready to Send) and CTS (Clear to
Send) signals. If the modem's transmit data buffer is about to overflow, it
drops CTS, signaling the DTE to halt its flow of data. When the buffer is
ready to accept more data, the modem raises CTS and the flow resumes.
In the same way, if the UART's receive buffer or the communications
software's buffer is full, the software can drop RTS to signal the modem to
stop sending data.

If available, hardware flow control is the preferred method of flow control,
and it is the default configuration. It is enabled by &K3. &K6 enables both
hardware and software flow control. &K0 disables all flow control.

Hardware flow control must also be enabled in your communications software.

Software Flow Control

In case hardware flow control is unavailable, data flow can also be controlled
through the software signals XON and XOFF. Unlike other characters, XON and
XOFF are treated as commands by a modem in data mode, and are ordinarily not
passed along in the data stream to the remote modem.

XOFF is the signal to the modem from the DTE or the DTE from the modem to
stop data flow; it is normally ASCII 19d (13h), which is equivalent to v-S,
but it can be changed through S33. XON is the signal to resume data flow; it
is normally ASCII 17d (11h), which is equivalent to v-Q, but it can be
changed through S32.

The drawback to software flow control is that the XON and XOFF characters may
unintentionally appear in binary data, aborting a file transfer.

Software flow control is enabled by &K4. &K6 enables both hardware and
software flow control. &K0 disables all flow control. Software flow control
must also be enabled in your communications software.

______________________________________________________________________________
6**Leased-Line Operation**

If your applications call for frequent or continuous data transfer between
the same two endpoints, it may be more efficient to establish a permanent
communications circuit between them than to pay for repeated dial-up
connections. Such a permanent circuit, usually rented from a telephone
company or other common carrier, is referred to as a leased line.

A leased line can consist of either two wires or four wires. In a two-wire
leased line, data is transmitted and received over the same pair of wires,
just as in a dial-up connection.

Your modem can operate either synchronously or asynchronously over a two-wire
voice-grade leased line.

Connections

To connect your modem to a leased line, follow the installation instructions in
Chapter 2. For a two-wire leased line, plug one end of the supplied RJ-11
modular telephone cable into the modem's LEASE jack, and the other into the
leased-line wall outlet.

Configuring the Modems

Configure both modems for leased-line operation with the AT&L1 command.

Establishing a Connection

Because the leased link is permanent, establishing a data connection does not
require dialing or ringing. You must therefore manually designate one modem
as the originating modem and the other as the answering modem.

It is also possible to designate the originating and answering modems in
software. The command ATD forces a modem to go off-hook in originate mode,
and ATA forces a modem to go off-hook in answer mode.

ATD and ATA store the current mode selection in S14, bit 7: 0 for answer and
1 for originate (the default). (For more about S-registers, see Chapter 6.)
You can also make the selection by writing to this register directly:
ATS14=138 (the default) designates an originating modem, and ATS14=10
indicates an answering modem. ATH1 then causes the modem to go off-hook in
the selected mode. ATH0 causes it to go back on-hook.

Whether you configure the mode selection with AT commands or S-registers, you
can save it in a stored profile (AT&W0 or AT&W1) for easy recall. Once the
profile has been loaded, ATH1 takes the modem off-hook in the selected mode.
(For more about profiles, see Chapter 3.)

Once connected and configured, the modems attempt to establish a connection
for the time specified in register S7. (See Chapter 6 for a description of
S-registers.) Any character sent by the DTE to the modem aborts this attempt.
If successful, the modems remain connected until carrier is interrupted for
the time specified in register S10. To reduce the likelihood of disconnection,
this value should be set as high as possible.

If the connection is unsuccessful or interrupted, the modems continue to
retry until a successful connection is established.

Transmit Level

You can adjust the modem's transmit level over a leased line by changing
S-register 99. This register specifies transmit power ranging from 0 dBm to
-15 dBm in multiples of -1 dBm. The default is -10 dBm. This setting is
effective only during leased-line operation.
______________________________________________________________________________
7**Fax Operation**

To send and receive fax messages over your modem, you need a personal computer
and fax software. When you receive a fax message, the modem performs protocol
handshaking with the remote fax machine or fax modem and passes the incoming
data to the fax software, which decodes it to a bit-mapped image and stores
the image as a disk file. When you send a message, the fax software codes a
file as a bit-mapped image and passes the corresponding data to the modem,
which sends it out over the telephone line to a remote fax machine or fax
modem.

EIA Class 1 and Class 2 fax commands are a set of extended AT commands defined
by the EIA/TIA for controlling a fax modem. These commands and responses are
described briefly in Tables 8.1 and 8.2. Except for the standard AT commands
D and A to originate and answer a call, all fax commands begin with +F. The
user does not normally need to understand the details of these commands,
which are hidden by the fax software interface. Entering a ? after the = in
the command will cause the modem to return a range of values possible for that
command.

Table 7.1. Fax Class 1 Commands
Command                 Function
Service Class ID
+FCLASS=                Service class

Fax Class 1 Commands
+FTS=n                  Stop transmission and wait
+FRS=n                  Receive silence
+FTM=n                  Transmit data
+FRM=n                  Receive data
+FTH=n                  Transmit data with HDLC framing
+FRH=n                  Receive data with HDLC framing

Class 2 Action Commands
D                       Originate a call
A                       Answer a call
+FDT                    Data transmission
+FET=N                  Transmit page punctuation
+FDR                    Begin or continue phase C receive data
+FK                     Session termination

Class 2 DCE Responses
+FCON                   Facsimile connection response
+FDCS:                  Report current session
+FDIS                   Report remote identification
+FCFR                   Indicate confirmation to receive
+FTSI:                  Report the transmit station ID
+FCSI:                  Report the called station ID
+FPTS:                  Page transfer status
+FET:                   Post page message response
+FHNG                   Call termination with status
+FMFR?                  Identify manufacturer
+FMDL?                  Identify model
+FREV?                  Identify revision
+FDCC=                  DCE capabilities parameters
+FDIS=                  Current sessions parameters
+FDCS=                  Current session results
+FLID=                  Local ID string
+FCR                    Capability to receive
+FPTS=                  Page transfer status

Class 2 Session Parameters
+FCR=                   Capability to receive
+FAA                    Adaptive answer
+FBUF?                  Buffer size (read only)
+FPHCTO                 Phase C time-out
+FAXERR                 Fax error value
+FBOR                   Phase C data bit order
______________________________________________________________________________
8**Diagnostic Tests**

Your modem offers several diagnostic tests that you can perform to test its
operation, its link to your DTE, and its link to another modem:

*       Local analog loopback
*       Local digital loopback
*       Remote digital loopback

These tests can help you locate and isolate a failure in the local modem, a
remote modem, the serial interface, the telephone connection, or the computer
and communications software.

All tests are initiated by AT&Tn commands entered from the keyboard of a
terminal or a computer running communications software in terminal mode.

The modem should be off-line and in direct, unbuffered mode (&Q0 or &M0)
before beginning the test. It is a good idea to start by typing

        AT  <ENTER>

to test the operation of the terminal or communications software, the
integrity of its link to the modem, and the modem's ability to respond to
commands. If everything is working, the modem responds

        OK

Test Timer

The value of the S18 register determines the duration of a test in seconds,
from 0 to 255. It is usually convenient to specify the value of this timer
as part of the test command.

The default for S18 is 0, meaning that the test runs indefinitely. To
terminate an indefinite test (or to terminate a timed test before it is over),
type

        AT&T0  <ENTER>

This command terminates the test in progress.

Alternatively, you can type

        ATH  <ENTER>

to hang up.

Self-Test

Some tests include a self-test, which is simply a test pattern generated by
the modem and checked for errors. If you do not run the self-test, you have
to enter test data yourself at the terminal.

Single-Modem Tests

There are two tests you can perform without the aid of another modem: local
analog loopback with and without self-test.

Local Analog Loopback

In the local analog loopback test, digital data from the DTE is sent to the
modem's transmitter, modulated into analog form, looped back to the modem's
receiver, demodulated, and returned to the DTE. This test therefore tests the
modem, the DTE, and the connections between them.

This test is initiated by the command

        ATS18=duration&T1  <ENTER>

where duration is the length of time you want the test to run. If instead you
type simply AT&T of the test is determined by the current value of the S18
timer. If a connection exists when you issue the test command, the modem
terminates it and begins the test.

When the test begins you see a message giving the connect rate.

Type any characters. To pass the test, the modem should echo them back to the
screen exactly as you typed them. (You see the characters only once, not
twice.).

Local Analog Loopback with Self-Test

This test is identical to the previous one, except that the modem itself
generates the data, which you can see on-screen as printable ASCII characters.
The command to begin the test is

        ATS18=duration&T8 <ENTER>

When the test is terminated by expiration of S18 or the &T0 or H command, the
modem reports the number of errors detected to the DTE. For the modem to pass
the test, this number should be zero.

Two-Modem Tests

The remaining tests require a second modem (called the remote modem, although
it does not have to be far away from the test modem, only connected to it
through a telephone line).

Local Digital Loopback

In the local digital loopback test, the local modem receives analog data from
the remote modem, demodulates it into digital form, loops it back to its own
transmitter, remodulates it into analog form, and retransmits it to the remote
modem. This test therefore tests your local modem, the telephone line, and the
remote modem and DTE (presumed to be good). The remote modem does not need to
have any special capabilities, but you need the cooperation of someone at the
remote site.

To perform this test, establish a connection with another modem, and then give
the command

        ATS18=duration&T3  <ENTER>

to begin local digital loopback. The actual testing is done at the remote
site: any characters typed on the remote keyboard should be echoed back to
the remote screen exactly as they were typed.

There is no self-test available for this test.

Remote Digital Loopback

The remote digital loopback test can be performed with an unattended remote
modem, but the remote modem must have CCITT V.54 remote digital loopback
capability.

In this test, the local modem sends a remote digital loopback request to the
remote modem. If the remote modem has this capability and it is configured to
accept the request, it establishes a connection. The local modem modulates
digital data from its local DTE into analog data and transmits it to the
remote modem. There it is received, demodulated into digital form, looped
back to the remote transmitter, remodulated into analog form, and
retransmitted to the local modem. The local modem in turn demodulates it and
sends the resulting digital data to the local DTE. This test therefore tests
your local DTE and modem, the connections between them, the telephone line,
and the remote modem (presumed to be good).

The command for this test is

        ATS18=duration&T6  <ENTER>

As in the local analog loopback test, all characters you type at the local
keyboard should be echoed perfectly back to the screen. The modem remains on-
line after the test terminates.

By default, a V.54-compliant modem is configured to accept requests for
remote digital loopback from another modem. Requests can be denied by
entering the command

        AT&T5  <ENTER>

and re-enabled by

        AT&T4  <ENTER>

Remote Digital Loopback with Self-Test

This test is identical to the previous one, except that the local modem itself
generates the data, which you can see on-screen as printable ASCII characters.
The command to begin the test is

        ATS18=duration&T7 <ENTER>

When the test is terminated by expiration of S18 or the &T0 or H command, the
modem reports the number of errors detected to the DTE. For the modem to pass
the test, this number should be zero. The modem remains on-line after the test
terminates.
Download Driver Pack

How To Update Drivers Manually

After your driver has been downloaded, follow these simple steps to install it.

  • Expand the archive file (if the download file is in zip or rar format).

  • If the expanded file has an .exe extension, double click it and follow the installation instructions.

  • Otherwise, open Device Manager by right-clicking the Start menu and selecting Device Manager.

  • Find the device and model you want to update in the device list.

  • Double-click on it to open the Properties dialog box.

  • From the Properties dialog box, select the Driver tab.

  • Click the Update Driver button, then follow the instructions.

Very important: You must reboot your system to ensure that any driver updates have taken effect.

For more help, visit our Driver Support section for step-by-step videos on how to install drivers for every file type.

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