Using Packet for connecting computers together

Robert A. Wilson n6tv@VNET.IBM.COM
Mon, 9 May 94 17:13:14 PDT

We used a packet link once back in 1991.  Worked OK, for hours, then it
started cycling and we shut if off.  Here's the write up we followed
at the time.  Try it, you might like it.  -- Bob, N6TV

                Using K1EA between "remote" sites
                        Paul Evans, G4BKI

Just occasionally you might be confronted with a similar problem to
the one we had at GW8GT in the CQWW CW Contest, a long(ish) distance
between the two run and multiplier station shacks.  This short note
tells you how to get around the problem and still link K1EA multiplier
stations together.

When two or more computers are in the same building and linked using
the serial ports, it is simply a matter of connecting them up and then
getting to grips with K1EA itself.  However, the station we were
running had two shacks, one housing the HF run station and two
multiplier rigs and the other about 600 yards away housing the HF
multiplier station.  This arrangement simply suited the layout of
antennas on site and serves to reduce interference problems between
stations.  The problem was how do you link two computers over that
distance without running a long (RF susceptible) cable?  Luckily
packet radio saves the day again!

The answer is simply to connect a TNC to the computer at each end and
then run it in transparent mode to shovel the data over.  This has the
added advantage that the TNCs provide data buffering and high
integrity to the transmission of the data.  In normal circumstances,
if one K1EA machine goes down and another station is still logging
calls, any data sent out over the serial line will be lost.  The
result is that, when the other machine has been re-booted, there will
be a mismatch between the two logs held.  This can provide endless
hours of fun in post-even "fixing"!!!!  This remote linking also does
away with this problem unless one end is down for a very long time
(about 200 QSOs worth!).

In theory the linking sounds simple but, in practice, it has to be
done very carefully in the correct sequence.  Here's how it's done:

Chose a very clear frequency on any band you like.

Connect up your radios and serial links to the computer as per your
normal packet set-up.

Using a terminal program, set ABAUD 4800, PACLEN 255, DWAIT 0, FRACK

Boot K1EA on your machine.
At the front page set for a LOCAL TNC.
Finish the rest of the front page setup and press CTRL-Enter.
Wait for K1EA to reach its status page.
Press any key to start the main logging routine.
Type SETUP and set COM1 to 4800 and TNC.
Press CTRL-Enter.
You are now back at the callsign entry field.
Press Alt-T to open the packet window.
Press CTRL-C to make sure you are in command mode of the TNC.
Now connect, in normal packet style, to the other station (use
different callsigns in MYCALL!)
Press CTRL-C to force command mode again.
Enter t to start transparent mode.
Press Alt-T to close the packet window.
Type SETUP in the callsign field.
Set COM1 to 4800 and Multi-n where n is the number of your station.
Press CTRL-Enter to save.

The link is now established and should stay active for the whole
weekend!  If the system crashes terminally (i.e. loses connection),
then reset the TNC and perform the above procedure again (missing out
the parameter settings).

RETRY 0 in the TNC is VERY important, because otherwise if one end of
the link were to go down it will soon timeout.  RETRY 0 ensures that
not only will the link stay up, but that after a crash recovery will
be swift.

Use of Converse mode with CR OFF and CPACTIME was attempted but, for
some reason, K1EA didn't like it and got garbled data.  It should
have worked, but the transparent mode route seems to be 100% reliable
so I have stuck to it.

This procedure allows you to interconnect any number of K1EA stations,
operating over any (!) distance that can be bridged by a radio link.
As for the legality of spacing the multiplier stations by large
distances, I'm not sure, but certainly when you are at the same postal
address which was the case at GW8GT then all is OK.

If anybody else has cause to use this type of setup I would be very
interested to hear of any observations that are made.

Paul Evans G4BKI - VP9KF - 8P9FT
Courtesy of Chiltern DX Club newsletter, December, 1990
relayed by Dick Dievendorff, G0MFO, AA6MC