async-fa.tr3

传真编程的一些文档

	    Modulation Control Register.  The DCE will wait up to the
	    time set in Register 7 for carrier to be detected.	If the
	    signal fails to be detected within that time, the modem
	    returns to Command Mode and sends the NO CARRIER response
	    code.

		 If the selected mode is detected (Receive Line Signal
	    Detect in the proper mode), the DCE will send the CONNECT
	    result code to the DTE.

		 If a signal is detected, but it is not the selected
	    mode, the DCE will send a CERROR (Connect Error) result code
	    to the DTE.  This result code may optionally contain a
	    numeric code indicating the type of signal that the DCE has
	    determined that it is detecting.

		 If the modulation selected is TONE, the CONNECT result
	    code will be returned when the selected tone is detected for
	    the period of time set in Register 9 , the Carrier Detect
	    Response Time register, (0.1 second increments, default 0.6
	    seconds).  The DCE will then return to command mode.

		 In data modes, the DCE will return to Command Mode upon
	    loss of carrier for the period of time set in Register 10,
	    sending the normal NO CARRIER result code.

		 The DCE will obey the configured flow control from the
	    DTE.

		 If the DTE sends any data to the DCE other than XON or
	    XOFF while the DCE is in a Receive mode,  the DCE will
	    return to command mode.  If the data from the DTE which
	    aborts the receive process is a valid command, the command
	    will be executed correctly.

		 The DTE may force the DCE to command mode by making
	    Circuit CD (Data Terminal Ready) false, if so configured.


	    Page 7				    TR30.4.1/89-01001R4

	    2.3.2.3 HDLC Transmit

		 The command AT+FTH causes the DCE to transmit frames in
	    HDLC protocol using the modulation mode chosen in the
	    Modulation Control Register.  If, when the command is
	    executed, the mode set in the Modulation Control Register is
	    not a valid synchronous mode, the response code ERROR will
	    be returned by the DCE and the DCE will return to command
	    mode.
		 The DCE will return the CONNECT result code and
	    transmit training followed by flags until the first byte of
	    data is sent by the DTE.  When the buffer becomes empty the
	    DCE will append the Frame Check Sequence and a closing Flag
	    to the frame and return to Command Mode, sending the result
	    code CONNECT to the DTE.  The DCE will continue to send
	    flags until one of the following actions is taken by the
	    DTE.

		 . The DTE sends additional data.  This action causes
		   the DCE to send another frame.

		 . The DTE forces the DCE to Command Mode via Circuit CD
		   (Data Terminal Ready) or the Escape Sequence.

		 . The period of time in Register 10, the Carrier Detect
		   Response Time, elapses from the time when the DCE
		   reported the CONNECT result code without the DTE
		   sending additional data to the DCE.

		   The DCE detects the FINAL bit in the C-field of the
		   frame.

		 When the DCE stops transmitting and returns to Command
	    Mode and sends the the DTE the OK result code or the NO
	    CARRIER result code in the case of S10 expiration.

		 The DCE performs HDLC zero insertion and Frame Check
	    Sequence generation while in this mode.

		 The DCE buffers data in HDLC transmit mode.   The DCE
	    will use the configured method of flow-control to pause the
	    DTE as necessary.
	    


	    Page 8				    TR30.4.1/89-01001R4

	    2.3.2.4  HDLC Receive

		 The command AT+FRH causes the DCE to receive frames in
	    HDLC protocol using the modulation mode selected in the
	    Modulation Control Register.  If, when the command is
	    executed, the mode set in the Modulation Control Register is
	    not a valid synchronous mode, the response code ERROR will
	    be returned by the DCE and the DCE will return to command
	    mode.

	    If the selected mode is detected (Receive Line Signal Detect
	    in the proper mode), the DCE will send the CONNECT result
	    code to the DTE.

		 If a signal is detected, but it is not the selected
	    mode, the DCE will send a CERROR (Connect Error) result code
	    to the DTE.  This result code may optionally contain a
	    numeric code indicating the type of signal that the DCE has
	    determined that it is detecting.

		 The DCE strips Flags and receives and buffers frames.
	    The received data, starting with the first non-Flag byte and
	    continuing through the last FCS byte will be transferred to
	    the DTE.  The DCE performs HDLC zero-deletion and error
	    checking.  When the last byte of FCS has been sent to the
	    DTE, the DCE may optionally inform the DTE of End-Of-Frame
	    by generating a BREAK signal.  After the FCS bytes,
	    following the optional BREAK, the DCE will inform the DTE of
	    the status of the frame reception by returning a result code
	    of OK, if the frame was received correctly, or ERROR, if the
	    frame was received in error.

		 The DCE will obey the configured form of flow control
	    from the DTE.

		 After sending the Result Code indicating the frame
	    reception is complete, the DCE continues to receive and
	    buffer data in the selected mode.  If the DTE issues another
	    HDLC Receive command, the buffered data will be sent to the
	    DCE and HDLC reception will proceed.  If any other command
	    is issued by the DTE, the DCE will stop the receive process.
	    Any buffered data will be discarded and the command will be
	    obeyed.

		 The DCE will return to Command Mode upon loss of
	    carrier for the period of time set in Register 9, sending
	    the normal NO CARRIER result code.


	    Page 9				    TR30.4.1/89-01001R4

		 In this mode, the DTE may force the DCE to command mode
	    with the Escape Sequence or by making Circuit CD (Data
	    Terminal Ready) false, if so configured.


	    2.4  Optional Features

	    2.4.1  Data Buffering

	    In order to allow a computer, such as a multi-user one,
	    which may not always be able to quickly respond to avoid
	    having under-run conditions when transmitting a facsimile,
	    significant buffering in the DCE may be desirable.	The
	    ability to buffer up to 3 seconds of data for transmission
	    (less than 4 kilobytes of buffer) may be provided as an
	    option.

	    2.4.2  DTMF Detection

	    A desirable feature of a multi-function DCE which is capable
	    of facsimile and various forms of data communications would
	    be to be able to detect Dual Tone Multi-Frequency digits to
	    tell a program what service the caller desires.

	    In this operation, the calling DCE would respond to a
	    secondary dialtone emitted by the answering DCE and send one
	    or more digits.  These digits would result in unsolicited
	    result codes to the DTE.


	    Page 11				    TR30.4.1/89-01001R4


	    2.4.2.1  Suggested DTMF implementation.

	    Examples:

		 Dial string at caller:  ATDT<number>@x (where x is a
	    digit).

		 Command sequence to answering DCE:

		 Upon Detection of RING:  ATH1+FT (The H1 causes the DTE
	    to come Off-Hook.  The @ in the dial string causes the DCE
	    to wait for silence before continuing.  The +FT with the
	    proper tone setting in register 65 causes the DCE to send a
	    short tone.  The DTE then goes into DTMF detect mode.

		 If the DCE detects a DTMF digit it sends the DTE an
	    unsolicited response code consisting of an ! (exclamation)
	    followed by the digit received.  The DCE is in a form of
	    Command Mode.  Any command sent to the DCE will cause it to
	    exit the DTMF detection mode and be obeyed.

		 Many of the currently available facsimile data-pumps
	    cannot quickly detect a DTMF digit without additional
	    hardware.  They are, however, capable of detecting the
	    column tones, allowing at least the digits 1, 2, and 3 to be
	    detected.

	    A better syntax may be determined by the TR30.4 group which
	    will satisfy this function.