[Trlog] Multi port using serial ports

William Till wtill at telusplanet.net
Wed Apr 23 00:13:10 EDT 2003

Networking can be really quite simple.  At VE5RI, we have had as many as 6
computers running TRLog in a daisy chain serial network.  We have found that
all we need is two wires.  We strung a 4 wire shielded cable because it was
what we had, but we are only using 2 of the wires, one connected to the
ground pin (pin 5 on a 9 pin port, 7 on a 25 pin port) at each serial port
and the other running from pin 2 on the first computer to 3 on the second,
then from 2 on the second to 3 on the third, etc. all around the loop back
to 3 on the first computer. Set up the logcfg file for the appropriate ports
on each computer.  Total loop length is probably something in the order of
100 feet, but could probably be much longer.  It is actually a type of null
modem loop if you think about it.

Works like a charm, simple (KISS) and never seems to be affected by RF even
with 3 or 4 legal limit amps going at once.  On occasion, we have had RF
problems with computers, but invariably have found that a toroid on the
keyboard line going into the affected computer cleans it up nicely.

Our computers are all old salvaged 486s operating on DOS 6.22 (No Windows!).
Not much capital tied up there - we save that for antennas and more
antennas.  One extra computer which is the station host's personal business
box and running Windows and DXTelnet is connected to an Internet cluster and
the output of the cluster is piped into another serial port on one of the
networked computers. Presto! Packet spots fed into all computers on the

Check network function by sending intercom messages (with ").  You can tell
instantly if everything is working.  You will hear the warble tone of a
successful message as soon as it is sent even before the message makes it
around the loop.  If it doesn't work, check your serial port assignments on
the computers.

So no expensive null modem cables or anything fancy here.  Try this - it
will work.

73 .. Bill

----- Original Message -----
From: "David Price" <wa4et at hotmail.com>
To: <trlog at contesting.com>
Sent: Tuesday, April 22, 2003 2:51 PM
Subject: [Trlog] Multi port uing serial ports

I want to mutiport to computers using the serial port. I have read to
prodeure and had a question.

do you use a std serial cable, or somthing equivalent to a null modem cable,
where the TX and RX are swaped



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