[na-user] loop networks
Sat, 06 May 2000 09:16:47 -0400
At 12:17 AM 5/6/00 -0700, K2KW wrote:
>A tip if a computer has gone off line... I make a few "loop-back" plugs
>from DB9/DB25's (the loop-back shorts TXD and RXD - pins 2 & 3? I dont have
>my manual in front of me to be sure). If a computer crashes, or you want to
>take a computer off line, just plug the loop-back onto the Y-connector
>feeding each computer. The loop-back completes the network, so there is
>minimal loss of data among the computers that are left on-line.
This works real well. At K8CC, we went a step further. For our loop
network, we brought serial cables from each computer to a central box in
the shack. The box ties all the serial cables together for the loop
network through toggle switches so that any computer can be taken out of
the network with just the flip of a switch.
We also added an LED to monitor the status of each serial line, like those
inexpensive COM port testers you can buy. A 2.7K 1/4W resistor and a
dual-color LED is all it takes. This is very useful for determining the
network status at a glance, or for troubleshooting serial cables. Its also
fun to watch when a QSO gets logged, as you can follow (with the blinking
LEDs) the QSO as it ripples around the network.
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