[TRLog] Serial config for multi-computers

[Stephen Merchant]

At 06:11 PM 3/23/98 -0700, you wrote:
>I am going to toy around with using multiple computers, but I was wondering
>if I needed multiple ports. I assume that I need to use a serial port
>connection from the first computer to a TNC. Also, a separate port for each
>radio connection, and a separate connection to the other downstream
>computers. Does the TNC data from the first computer get sent to al of them?
>I think I read that in the manual, but I wanted to confirm.

I assume you're going to interface packet to your multi network -- if so
you'll need a serial port for that.  And one for a radio, and one for the
network.  At N6RO we use one machine with 4 com ports and 2 lpts as the
"mother ship" of the network and connect packet to it.  Most of the other
machines have 2 or 3 com ports, which is plenty for connecting radio
interfaces and the network (one each.) 

>Regarding the interface between computers, do the connections alternate;
>i.e, Pin 2, 3, and 7 to Pins 3, 2, 7 respectively on the next computer? What
>about a third: do the pins switch again in a daisy-chain?. Or do you need a
>separate in and out port on each computer for the multi-network?

Build a y-adapter for each computer in the network so that each side of the
y- connects to one network cable and the single end of the y- connects to
your serial port.  I forget which pin is which without having the manual to
check, but basically you are just using one wire plus ground for each side
of the y-.  (I think I used pin 5 for grounding the shield, not 7.)  

>Any thoughts would be nice. I am hoping to link the Field Day computers, so
>packet will not be an issue, but the rest will be. How much cable has anyone
>used without having to go to Limited Distance MODEMs? I was hoping to use
>category 5 patch cords with the pins swapped in the adapters. This cable is
>shielded, but I would need about 50 feet between each computer.

At N6RO I have a couple of 40 footers and a bunch of 10's and we have no
problems while running six 1.5kw stations.  This weekend, for instance, we
will have 7 computers on the network.  Review the ARRL Handbook to make
sure you don't cut a network cable that is resonant on some ham band.  40'
is ok, I think 25' isn't.  Using decent shielded cable, you should be just
fine.  I recall K5TR and N6TR have tested the extreme outer limits of
inexpensive network cabling with TRLog -- anything Radio Shack sells (2
conductor plus shield) will be great.

Have fun!  It's a VERY solid network application.

73, Steve K6AW

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