max length of RS-232 network link?

Tyler Stewart
Tue, 11 Jul 1995 18:08:18 -0400

>The maximum length of the RS-232 runs is not affected by the fact the
>you are using the -LOOP mode of CT. It will solely be determined by
>the robustness of the particular interfaces you are using, and the
>RF integrity of the cables. Check me on this, but I think RS-232
>is spec'ed to a max of 500 feet.

Ummm...Dont think so...think it's closer to 50 feet.

>Things you can do to help it work:
>1. Make all your cables out of coax. RG-58 should work fine.
>2. Bring ferrite beads, just in case.
>3. If you have trouble, try running the network at a lower baud rate.
>4. Ultimately, you could go with optical fiber on the RS-232 links.
>   It's expensive, but it works. Talk to Rich, K5NA, who has done it.

Probably a cheaper alternative to item 4 would be to use an RS422 converter
at each computer.  If I remember right it requires a 2 pairs of wires (ie. 
telephone "twisted pair" cable), and it turns the unbalanced signalling of
RS232 into 2 pairs of balanced lines which are much less susceptible to
interference and it'll go a couple thousand feet.  This'll be a LOT cheaper
than fiber... and you could still work it into a loop configuration easily.

Tyler KF3P

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