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AR-210 Manual
3-10
If you do not want this effect, enable the <ESCAPE> translation with
ESCAPE OFF
. This will cause
all <ESCAPE> characters to be sent to the TNC as the dollar sign symbol. This does not affect
<ESCAPE> characters that are transmitted as packets.
Some terminals echo characters typed in locally, before the character is transmitted to the I/O
port. Also some terminal programs on computers may perform local echoing.
If the TNC also echoes characters, you will see two of every character. You can disable the echo
mode by setting
ECHO
to
OFF
.
A few terminals require particularly long time to respond to <CR> or <LF>. Some hard-copy ter-
minals require time to move the printer head to the beginning of the line following a <CR>.
Some display terminals require long times to scroll their screen following a <LF> character. If char-
acters are sent to such a terminal before it is ready, the character will be lost.
If your terminal always loses a few characters at the beginning of a line, you need to enable null
insertion. A null is character with ASCII code 0 and the TNC does not actually transmit nulls in this
mode, since they are misinterpreted by some computers terminal program a a BREAK signal.
The number of null intervals is set by the commands
NULLS
and null insertion after <CR>s and
<LF>s is separately enabled by
NUCR
and
NULF
.
EDITING COMMANDS
Several characters are used to correct mistakes in the text typed into the TNC. Except in the Trans-
parent Mode or if times packets are in effect in the Converse Mode, no text characters are inter-
preted by the TNC until it receives a <CR> or the send-packet (in Converse Mode). Until then, you
can delete and retype characters or cancel the line completely.
Control characters are normally chosen as editing characters.
SPECIAL OPERATING CONFIGURATIONS
The primary function on the TNC is to enable you to communicate with other stations via packet
radio. The AR-210 implements the AX.25 protocol (set of rules).
This protocol is designed primarily for point-to-point, two-party communications. You can also use
it, however, to simulate the common amateur net or round-table type of contact. You can specify
the AX.25 protocol level 2 version by setting it ON (Level 2, Version 2.0) or OFF (Level 2, Version
1.0).
Earlier in this section, you learned how to set your call sign and issue the CONNECT command to
take a specific station. These commands are the beginning of packet operation, which you will now
learn more about.
To establish a two-way connection, the TNC must know your station address and the address of
the party you wish to talk to.
To prepare your TNC for radio operation, first establish your call sign as the station address by us-
ing
MYCALL
(or just
MY
) command. This set the string that is used to identify packets transmitted
by your station (the protocol will not work if there is more than one station on the air with a given
address).
Page 25
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