Operation of TNC3/31 with Hayes-Commands

The TF and the related TNC3BOX contain the command #AT, which switches the TNC3 to Hayes-Mode.

With the DIP-switches set to 11, the TNC3 will start in Hayes-Mode at power-on. When calling TF with a script file containing the #AT command, the Turbofirmware will start immediately in Hayes-mode.

Hayes-commands are common with telephone-modems and are not optimal for use with packet-radio. But if a telephone-modem-link is to be replaced by a radio link with TNC3, the normal communication programs may be used without changes. You have to remember, that the response time of a radio link is much longer (maybe some seconds) compared with a full duplex telephone link (which has almost zero delay).

Every Hayes-command received correctly is acknowledged by 'OK'. As soon as a connection is established, the TNC changes to transparent mode, i.e. all data is transferred binary. With +++, the TNC exits transparent mode as usual with Hayes modems. The TNC will transmit the buffered data only if the maximum packet-length (set by paclen) is exceeded OR if the maximum time since the last character has expired (pactime)

AT DP call [viacall1 [viacall2 ...]] establish connection to call via digicall1 ...
    answer: CONNECT
    optional: 2:call = connect via Port 2

AT DT call [viacall1 [viacall2 ...]] same as AT DP

AT O change from command to transparent mode
    (allowed only if connected)

AT H disconnect (allowed only if connected)
    answer after disconnect: NO CARRIER

AT V0 answers of TNC in figures
AT V1 answers of TNC in text (verbose)
    OK (0) follows every valid command
    CONNECT (1) when DP was successful OR if a remote station connects
    NO CARRIER (3) on end of connection
    ERROR (4) parse error, wrong command syntax
    BUSY (7) remote station is busy (DM) or already connected
    NO ANSWER (8) remote station does not answer to connect request

AT E0 / AT E1 echo off / echo on. Show with AT E

AT &M0 / AT &M1 monitor mode off / on

AT &Q exit Hayes-mode, Reset.

AT Z dummy command, answer: OK

AT I1 show modem-baudrate. Answer e.g. 1200 OK
    (of the modem which was addressed last)
AT I3 show firmware version. Answer e.g. Version 168 OK
AT I4 show hardware identification. Answer e.g.: TNC3 OK

AT S20? or AT S20=? show e.g. S20-registers (paclen)

AT S0=x TNC accepts remote connects (yes: x=1), (no: x=0)
AT S21=x set pactime (x=1...2000 ms, default 500 ms)
AT S22=x set window size (x=1...7, default 5)
AT S25=x max. retries (x=1...255, x=0 means )
AT S30=call set own callsign (default NOCALL)
AT S31=x change to SLIP-mode (x=1), default: off (x=0)

some normal Turbo-Firmware settings (to be defined with the ESCAPE-command) are also valid in Hayes-mode.