| Commands for the TNC2 | Back to Menu page |
8BITCONV
This command enables the transmission of 8-bit
data in converse mode. Used with AWLEN - see below. For normal
packet operation, such as keyboard to keyboard transmissions, use of bulletin
board systems, and the transmission of ASCII files, 8BITCONV
should be OFF. If you need to transmit 8-bit data, set
8BITCONV ON and set AWLEN to 8. Make sure that
the TNC at the receiving end is also set up this way. This procedure is
normally used for transmission of executable files or a special non-ASCII data
set.
AWLEN
This parameter defines the word length used by the
serial input/output port of your TNC. For normal packet operation, as
described above, AWLEN should be set to 7. Set to 8 only if
you're going to send 8-bit data.
AX25L2V2
This command determines which level of AX.25
protocol you're going to use. If OFF, the TNC will use AX.25 Level 2, Version
1.0. If ON, the TNC will use AX.25 Level 2, Version 2.0. Note: Some early TNCs
will not digipeat Version 2.0 packets. With AX25L2V2 OFF, if
your TNC sends a packet and the packet doesn't get acknowledged the first time
it was sent, it will send it again and again, until an "ack" is received or
the TNC retries out. With AX25L2V2 ON, if your TNC sends a
packet and doesn't receive an "ack" the first time, it will send a poll frame
to see if the other TNC received the packet. If yes, then it would continue,
if not then it would send the last packet again. The advantage here is that
short poll frames are sent, rather than long packets containing data. This can
greatly reduce channel congestion. For VHF/UHF operation, it is almost
essential that every TNC have AX25L2V2 ON. Many operators have
suggested that Version 2.0 NOT be used on the HF bands as it tends to clutter
the frequency with poll frames. See the CHECK command below for related
information.
BEACON
Used with EVERY or AFTER to enable beacon transmissions.
n = 0 to 250 - specifies beacon timing in ten second intervals: 1 = 10
seconds, 2 = 20 seconds, 30 = 300 seconds or 5 minutes, 180 = 1800 seconds or
30 minutes, etc.
Examples:
BTEXT
Can contain up to 120 characters.
CHECK n
Sets a timeout value for a packet connection. When
a connection between your station and another seems to "disappear" due to
changing propagation, channel congestion or loss of the path, your TNC could
remain in the connected state indefinitely. If the CHECK
command is set to a value other than 0, the TNC will attempt to recover the
connection or disconnect. The action taken depends on the setting of
AX25L2V2. The value of CHECK (n) may be set
from 0 to 250 and the timing is based on the formula of n * 10 seconds. (n = 1
is 10 seconds, n = 5 is 50 seconds, n = 30 is 300 seconds or 5 minutes, etc. A
value of 30 is a recommended value to use.) If CHECK is set to
0, it disables the command. If AX25L2V2 is ON, the TNC will
send a "check packet" to verify the presence of the other station if no
packets have been heard after (n * 10) seconds. If a response to the "check
packet" is received, the connection will remain. If no response is received,
the TNC will begin the disconnect sequence, just as if the
DISCONNECT command had been sent. If AX25L2V2
is OFF, after no packets are heard for n * 10 seconds, the TNC will not send a
check packet, but will begin the disconnect sequence.
CMSG
Enables the automatic sending of a connect message
whenever a station connects to your TNC. If CMSG is ON, the
TNC will send the message contained in CTEXT as the first
packet of the connection. CTEXT can contain up to 120
characters. Of course, you must have a message in CTEXT for
CMSG to function. This feature is often used when the station
is on but the operator is not present. The connect message is used to advise
the other station of that fact, and often says to leave a message in the TNC
buffer or mailbox. If CMSG is OFF, the CTEXT
message is not transmitted.
CONV (converse mode)
Your TNC will automatically switch to
this mode when you connect with someone, but you can also switch to this mode
by entering CONV <CR> at the Cmd: prompt. When you're in
converse mode and are NOT connected to another station, anything you type will
be transmitted via the path you set with the UNPROTO command.
CTEXT
Can contain up to 120 characters.
DAYTIME
Command has been used to set the date and time.
DISCONNECT
Command had been sent to disconnect the whole packet.
DWAIT
Used to avoid collisions, DWAIT is
the number of time units the TNC will wait after last hearing data on the
channel before it transmits. I have DWAIT set to 16, and have
found that to work well.
ECHO
If you do not see anything on the screen when you type, blindly enter
the following: ECHO ON <CR>
If you see two of everything that you type, such as MMYYCCAALLLL, enter: ECHO OFF
<CR>
FRACK
Determines how long your TNC will wait for an
acknowledgement before resending a packet. It shouldn't be set too low, or
you'll simply clutter up the frequency, yet it shouldn't be too high, or
you'll spend too much time waiting. I use FRACK set to 7, and
have found that to be a good overall value.
HEADERLN
If you have this turned ON, the header of each
packet is printed on a separate line from the text. If OFF, both the header
and packet text are printed on the same line.
KISS
Enables the TNC to act as a modem for a host
computer, allowing programs such as TCP/IP, the G8BPQ Packet Switch, various
BBS programs, and other programs using the Serial Link Interface Protocol
(SLIP) to be run. Before turning KISS on, set the radio baud
rate and terminal baud rate to the desired values. Set KISS to
ON and then issue a RESTART command.
MALL
If MALL is ON, you receive packets
from stations that are connected to other stations, as well as packets sent in
unproto (unconnected) mode. This should be ON for "reading the mail". If
MALL is OFF, you receive only packets sent in unproto mode by
other stations.
MAXFRAME
Sets the upper limit on the number of
unacknowledged packets the TNC can have outstanding at any time. (The
outstanding packets are those that have been sent but have not been
acknowledged.) MAXFRAME also determines the maximum number of
contiguous packets that can be sent during one transmission. The value can be
set from 1 to 7. The best value to use depends on the frequency conditions.
The better the conditions are, the higher the value you can use. If conditions
are poor due to frequency congestion, noise, or other variables, (shown by
lots of retries) MAXFRAME should be reduced to improve
throughput. The best value of MAXFRAME is determined through
experimentation. MAXFRAME of 1 should be used for best results
on HF packet.
MCOM
If ON, you see connect <C or SABM>, disconnect
<D>, acknowledge <UA> and busy <DM> frames in addition to
information packets. If OFF, only information packets are seen.
MCON
If ON, you see packets from other stations while
you're connected to someone else. This can get very confusing, but is useful
when your path is bad and you want to see if your packets are being digipeated
okay. If OFF, the monitoring of other stations is stopped when you're
connected to another station.
MFILTER
This command allows you to enter up to four ASCII
character codes, 0 - $7F, for the control characters that you want eliminated
from your monitored packets. Codes may be entered in either Hex or Decimal.
Here are the ASCII codes for some of the more troublesome control characters
found in monitored packets:
HEX DEC FUNCTION POSSIBLE RESULT
$07 07 Control G Rings your bell or "beeps" your speaker
$0C 12 Control L Form feed - could clear your screen
$13 19 Control S Can cause your screen to stop scrolling
$1A 26 Control Z Can clear your screen
$1B 27 Escape Can cause your cursor to move to a random
point on your screen and can raise havoc
with printer control.
AEA has added a new code, $80, that will not allow ANY control characters to be displayed on the user's screen from monitored packets.
MHEARD
An immediate command that causes the TNC to display
a list of stations that have been heard since the command.
MHCLEAR
was given or the TNC was powered on. This command is
useful for determining what stations can be worked from your QTH. Stations
that are heard through digipeaters are marked with an * on most TNCs. On the
AEA PK-232, the stations heard direct are marked with the *. (Check your TNC
manual.) The maximum number of stations in the list is 18. If more stations
are heard, earlier entries are discarded. Logging of stations heard is
disabled when the PASSALL command is ON. (See below.) If the
DAYTIME command has been used to set the date and time,
entries in the MHEARD list will show the date and time the
stations were heard.
MONITOR
This must be ON for you to monitor anything. When
ON, you see packets from other stations on the frequency you're tuned to. What
packets you see is determined by other commands from the list below. If
MONITOR is OFF, you only see the packets that are sent to you
while you're connected to another station.
Note: On some TNCs, such as the AEA PK-232, monitoring functions are
selected by a number after the MONITOR command, such
as:
MONITOR 3 or
M 3
Refer to your
TNC operating manual for details.
The following commands affect "monitoring", which is what you see on your
screen from stations you're NOT connected to.
MRPT
If ON, you see a display of all the stations used as
digipeaters along with the station originating the packet and the destination
station. If OFF, you see only the originating and destination stations. For
example, if you have MRPT ON, you might see a transmission
such as this:
K9AT>WB6QVU,W6PW-5*: I'll be leaving for the meeting at about
7:30.
If MRPT was OFF, the same transmission would look like
this:
K9AT>WB6QVU: I'll be leaving for the meeting at about 7:30.
In the first case, you can see that the W6PW-5 digipeater was being used.
The asterisk indicates which station you were hearing the packet from. In the
second case you have no idea if digipeaters are being used or what station you
were receiving.
MSTAMP
The date and the time the monitored packets are
received is indicated if the MSTAMP command is ON. If it's
OFF, the date/time stamp is not shown. NOTE: The date and time must be entered
into your TNC memory using the DAYTIME command before the
MSTAMP command will function.
I run my station with all of these commands, except MCON, turned ON so that I can really see what's happening on the frequency I'm monitoring. Try various combinations of these commands and then decide on the combination you like best for your station.
MYCALL
MYCALL ---- with your callsign in place of the dashed
lines, such as: MYCALL WB9LOZ followed by a carriage
return <CR>. (The carriage return key is labeled "Enter" or "Return" on
most keyboards.) All commands must be followed by a <CR>. This sets into
the TNC memory the call that you're going to use on the air. Now if you type:
MYCALL <CR> it should respond with your
callsign. If it does, you've proven that the computer to TNC link is working
fine.
PACLEN
Indicates the number of characters in the packets
you transmit, ranging from 0 to 255. (A value of 0 equals 256.) The more
characters you send per packet, the longer it takes to transmit the
information and the greater your chances are of noise, interference or another
station wiping it out. I've found a PACLEN of 80, which is the
length of one line, to be a good value. When working a station nearby,
PACLEN can be increased. When working a distant station, it
should be decreased.
PASSALL
Causes the TNC to display packets that have
invalid checksums. The error-checking is disabled. If PASSALL
is ON, packets are accepted for display, despite checksum errors, if they
consist of an even multiple of eight bits and are up to 330 bytes. The TNC
attempts to decode the address field and display the callsigns in standard
format, followed by the text of the packet. PASSALL can be
useful for testing marginal paths or for operation under unusual conditions.
PASSALL is normally turned OFF.
PERSIST
Used in conjunction with the
SLOTTIME command to provide less clutter on a busy
packet frequency. As more and more TNCs are upgraded to include the
PERSIST and SLOTTIME commands, fewer and fewer
packet collisions will occur. If you have these commands available in your
TNC, you should set DWAIT to 0 and set these commands for use.
Note: On some TNCs, such as the PK-232, you have another command that
determines whether you use DWAIT or
PERSIST/SLOTTIME.
PERSIST specifies a threshold value for a random-number
attempt to transmit. The value ranges from 0 to 255. 0 signifies a 1/256th
chance of transmitting every SLOTTIME; 255 allows the TNC to
key the transmitter every SLOTTIME. Through experimentation,
it has been determined that the best value for PERSIST is in
the 60 to 70 range.
PPERSIST
command (with 2 P's). Set it ON to use
PERSIST/SLOTTIME; set it OFF to use
DWAIT. I strongly recommend that you set
PPERSIST to ON.
RESTART
RETRY
Your TNC will retransmit a packet if it doesn't
receive an acknowledgement from the station you're working.
RETRY indicates the number of times the TNC will try to get
the packet through before giving up and disconnecting. This can be set from 0
to 15, but I've found 8 to 10 to work well. Less than that causes an
unnecessary disconnect if the channel happens to be busy, but more than that
clutters up the channel. Do NOT set RETRY to 0. That means
infinite retries, and serves no useful purpose. It simply clutters up the
frequency needlessly.
SCREENLN n
This parameter determines the length of a line
of text on your computer screen. The value may be 0 to 255, and is usually set
to 40 or 80 depending on the screen display you have. A carriage return and
line feed <CR/LF> are sent to the terminal in Command and Converse modes
when n characters have been displayed. A value of zero inhibits this action.
If your computer automatically formats output lines, this feature should be
disabled.
SLOTTIME
This command determines the time interval the TNC
waits between generating random numbers to see if it can transmit. This random
number generation and the value of PERSIST work together to
provide smoother operation on a busy packet frequency. The
SLOTTIME value may be set from 0 to 250. Through
experimentation it has been determined that the best value for
SLOTTIME is in the range of 10 to 20.
TRANS
This is an immediate command causing the TNC to
change from Command mode to Transparent Mode. Transparent mode is used when
you want to send data such as executable programs where characters in the data
would conflict with the operation of the TNC. Characters such as "Control C",
"Control R", "Control S", "carriage return", "linefeed", etc. all effect the
operation of the TNC when in Converse Mode. In Transparent Mode none of the
data characters affect the operation. All eight bits of each character are
sent to the radio exactly as they are received by the TNC from the computer or
keyboard. Packets are transmitted at regular intervals set by the
PACTIME command or whenever a full packet of information is
ready. The receiving TNC must also be in Transparent mode and nodes and
digipeaters cannot be used in the transmit path. Since the characters normally
used for TNC operation have no affect in this mode, a special procedure is
required to exit Transparent Mode and return to Command Mode. Refer to your
TNC operating manual for details on how this procedure is performed on your
particular TNC.
TXDELAY n
This parameter tells the TNC how long to wait
before sending data after it has keyed the transmitter. All transmitters need
some start up time to put a signal on the air. Some need more, some need less.
Synthesized radios and radios with mechanical relays need more time, while
crystal controlled radios and radios with diode switching require less time.
External amplifiers usually require additional delay. Experiment to determine
the best value for your particular radio. TXDELAY can also be
useful to compensate for slow AGC recovery or squelch release times at the
distant station.
UNPROTO
Designates the path used when you send BEACONS or
when you're in converse mode and NOT connected to another station. The default
is CQ, but you can enter a series of digipeaters if you wish, or a specific
group or club name. Some examples:
If you include digipeaters in your UNPROTO path, you will
have to change the information for each frequency you use. (BEACONS will be
discussed in a later part of this series.)
Packets sent via UNPROTO are sent only once and are not acknowledged, so there
is no guarantee that they'll get through. This mode is used frequently for
sending CQ's.
There are many additional commands available to you. You should also check your manual for information on the CMDTIME, PACTIME, START, STOP, TRFLOW, TXFLOW, XFLOW, XOFF and XON commands before using Transparent Mode.