218/0049z DB0KG , 910218/0027z DK0MAV
de DK9AH @ DK0MAV


                            COMMAND SUMMARY
                            ===============

   COMMAND        PARAMETER               DESCRIPTION
   -------        ---------               -----------
     A (1)            0             Auto linefeed disabled
                      1             Auto linefeed enabled
     C        Cs1 [Cs2 ... Cs9]     Connect path (0=unproto path)
     D                              Disconnect
     E (1)            0             Echo input disabled
                      1             Echo input enabled
   * F (4)           1-15           Frame acknowledge (seconds)
     G               [0]            Get information (host mode)
                     [1]            Get link status (host mode)
   * I                Cs            Tnc source callsign
     JHOST (0)        0             Terminal mode enabled
                      1             Host mode enabled
     L              [0-4]           Display channel status
     M (IU)        NIUSC+-          Monitor mode
   * N (10)          0-127          Number of tries (0=forever)
   * O (4)           1-7            Number of outstanding I frames
     P (64)          0-255          P-persistence value
     QRES                           Re-start firmware
     R (1)            0             Repeater disabled
                      1             Repeater enabled
     S (0)           0-4            Select channel (0=unproto)
     T (30)          0-127          Transmitter delay (10ms)
     U (0)   0      [text]          Unattended mode disabled
             1      [text]          Unattended mode enabled
   * V (2)            1             Version 1 protocol initiated
                      2             Version 2 protocol initiated
     W (10)          0-127          Slot time interval (10ms)
     X (1)            0             Transmitter PTT disabled
                      1             Transmitter PTT enabled
     Y (4)           0-4            Maximum connections
     Z (3)            0             Flow disabled, xon/off disabled
                      1             Flow enabled, xon/off disabled
                      2             Flow disabled, xon/off enabled
                      3             Flow enabled, xon/off enabled
     @B                             Display number of free buffers
     @D (0)           0             Full duplex disabled
                      1             Full duplex enabled
     @S                             Display current link state
     @T2 (100)       0-65535        Timer T2 interval (10ms)
     @T3 (18000)     0-65535        Timer T3 interval (10ms)
     @V (0)           0             Callsign validation disabled
                      1             Callsign validation enabled

      Default values are shown in parenthesis

   *  These commands are applicable to each connection channel
        (Values set on channel 0 are used upon power up and
         disconnect to initialize each connection channel)



                          COMMAND DESCRIPTION
                          ===================

        The 'A' command is used to enable or disable  the  automatic
   insertion of LINEFEED characters after CARRIAGE RETURN characters
   to the terminal.

        The 'C' command is used to initiate a link connection.  Note
   that 'v' or 'via' is not required (but is  allowed)  between  the
   destination callsign and the digipeater callsigns.  A 'C' command
   may be  issued  on  a  channel  already  in  use  to  change  the
   digipeater callsigns, but not the destination  callsign.   A  'C'
   command issued when channel 0 is selected sets the unproto path.

        The 'D' command is used to initiate  a  link  disconnection.
   If there is unsent or unacknowledged information  remaining,  the
   disconnect request frame will not be sent until  all  information
   has been transmitted and acknowledged.  No additional information
   will be received after the 'D' command has been issued.  A second
   'D' command may be entered  to  force  the  transmission  of  the
   disconnect request frame before all information has been sent and
   acknowledged.  A 'D' command issued during the establishment of a
   link or after a disconnect request  frame  has  been  transmitted
   will cause an immediate return to the disconnected state.  A  'D'
   command issued on a disconnected channel will  re-initialize  the
   connection dependent parameters to the values stored  in  channel
   0.

        The 'E' command is used to enable or disable the echoing  of
   input (commands and information) to the terminal.

        The 'F' command is used to  set  the  frame  acknowledgement
   interval.  This interval is used to compute the timeout  interval
   before a packet is retransmitted, using the formula:

        time (seconds) = frame ack * (2 * number of digipeaters + 1)

   A separate frame acknowlegement interval value is maintained  for
   each connection channel.  The value stored in channel 0  is  used
   to  initialize  each  connection  channel  upon   power   up   or
   disconnection.

        The 'G' command is used to interrogate virtual TNC  channels
   when host mode is enabled.  If no  parameter  is  specified,  the
   next chronological item (information  or  link  status)  will  be
   returned, provided there is one.   This  command  is  invalid  in
   terminal  mode.   A  later  section  is  devoted  to  host   mode
   operation.

        The 'I' command is used to set the TNC source callsign.  The
   initial value is all blanks.  Changing the  TNC  source  callsign
   while connected is not permitted.  If the TNC source callsign  is
   left blank, the TNC will not allow connect  commands  or  unproto
   transmissions.  The callsign stored  in  channel  0  is  used  to
   initialize   each   connection   channel   upon   power   up   or
   disconnection.

        The 'JHOST' command is used to select between  terminal  and
   host modes.  A later section is devoted to host mode operation.

        The 'L' command is used to display the link status of one or
   all channels.   Information  displayed  includes  the  connection
   path, number of receive frames not yet displayed, number of  send
   frames not yet transmitted, number of transmitted frames not  yet
   acknowledged, and the  current  retry  count.   A  '+'  character
   preceeding the channel number indicates  the  currently  selected
   channel.  Operation of this command when host mode is enabled  is
   somewhat different, and is described in a later section.

        The 'M' command is used to set the  frame  monitoring  mode.
   The command parameter determines the types of  frames  monitored,
   and is a list of desired frames chosen from the  letters  in  the
   following table:

        LTR       FRAME
        ---       -----
         N        None
         I        I frames
         U        UI frames
         S        Supervisory frames
         C        Monitor while connected
         +        Call signs to be included (maximum of 8)
         -        Call signs to be excluded (maximum of 8)

   The '+' and '-' parameters may not be used together.   If  either
   is used, it must be the last parameter (followed by one to  eight
   callsigns, if applicable).  If no list of callsigns is  specified
   to be included or excluded, all callsigns will be candidates  for
   monitoring.  Entering a '+' or '-' with no callsigns  will  empty
   the list.

        The 'N' command is used to set the maximum number of times a
   frame  will  be  transmitted  without  receiving  an  appropriate
   acknowledgement, before a link failure is  assumed.   A  separate
   maximum number of tries value is maintained for  each  connection
   channel.  The value stored in channel 0  is  used  to  initialize
   each connection channel upon power up or disconnection.

        The 'O' command  is  used  to  set  the  maximum  number  of
   unacknowledged I frames that may be outstanding at any one  time.
   A separate maximum number of unacknowledged  I  frames  value  is
   maintained for each connection  channel.   The  value  stored  in
   channel 0 is used to  initialize  each  connection  channel  upon
   power up or disconnection.

        The 'P' command is used to set the p-persistence value.   P-
   persistence is used  during  simplex  operation  as  a  means  of
   channel  arbitration.   Whenever   there   are   frames   to   be
   transmitted, the TNC first waits for a clear channel.   Once  the
   channel is clear, a random number between 0 and 255 is generated.
   If the random number is less than or equal to  the  p-persistence
   value,  the  PTT  line  is  asserted  and  transmission   begins.
   Otherwise, the TNC delays for the slot time interval set  by  the
   'W' command and the entire process is repeated.

        The  'QRES'  command  is  used  to  restart  the   firmware,
   including re-initialization  of  battery-backed  RAM  to  default
   parameters.

        The 'R' command is used to enable or disable the digipeating
   of frames.

        The 'S' command  is  used  to  select  the  current  channel
   number.

        The 'T' command is used to set the transmitter  keyup  delay
   interval.  The parameter is specified in 10ms increments.

        The 'U' command is used  to  enable  or  disable  unattended
   modes.

        The 'V' command is used to select whether  version  1  or  2
   protocol will be used to initiate a link connection.  A  separate
   protocol version value is maintained for each connection channel.
   The value  stored  in  channel  0  is  used  to  initialize  each
   connection channel upon power up or disconnection.  Interrogating
   this parameter during a  connection  will  reflect  the  protocol
   version currently being  used  on  that  channel.   Changing  the
   protocol version during a connection is not permitted.

        The 'W' command is used to set the p-persistence  slot  time
   interval.  P-persistence is used during simplex  operation  as  a
   means of channel arbitration.  Whenever there are  frames  to  be
   transmitted, the TNC first waits for a clear channel.   Once  the
   channel is clear, a random number between 0 and 255 is generated.
   If the random number is less than or equal to  the  p-persistence
   value set by the 'P'  command,  the  PTT  line  is  asserted  and
   transmission begins.  Otherwise, the TNC delays for the slot time
   interval and the entire process is repeated.   The  parameter  is
   specified in 10ms increments.

        The 'X' command is used to enable or disable the transmitter
   PTT line.

        The 'Y' command  is  used  to  set  the  maximum  number  of
   connections that may  established  by  incoming  requests.   This
   command has no  effect  on  the  operators  ability  to  initiate
   outgoing connection requests.

        The 'Z' command is used to enable or  disable  flow  control
   and xon/xoff handshaking to the terminal.   If  flow  control  is
   enabled, output to the terminal will be inhibited while  entering
   commands or information.  If flow control is disabled, output  to
   the terminal will not be restricted.  Flow control  and  xon/xoff
   handshaking should be disabled during periods in which the TNC is
   operated without a terminal, to  avoid  suspending  output  which
   will consume buffers.  If xon/xoff handshaking  is  enabled,  crt
   scrolling may be stopped and started using CONTROL-S and CONTROL-
   Q characters.  Flow control  and  xon/xoff  handshaking  are  not
   performed when host mode is enabled.

        The '@'  command  is  a  software  maintenance  command.   A
   parameter of 'B' will display the number of  free  buffers.   The
   'D' parameter is used to enable or disable full duplex  operation
   of the HDLC port.  A parameter of 'S' will  display  the  current
   link state.  The 'T2' parameter is  used  to  set  the  timer  T2
   interval, just as the 'T3' parameter is used to set the timer  T3
   interval.  The timer intervals are specified in 10ms  increments.
   Timer T2 controls  the  amount  of  delay  between  the  time  an
   information frame is received and the time the resulting response
   frame  is  sent.   This  delay  allows  multiple  frames  to   be
   acknowledged with a single response.  Timer T3 is  used  maintain
   link integrity.  If there is no activity during the T3  interval,
   the TNC  will  poll  to  verify  the  distant  station  is  still
   connected.  The 'V'  parameter  is  used  to  enable  or  disable
   callsign validation.




(TNC2) DD9EP de DK0MWX>r tnc2 79
