From: utzoo!decvax!ucbvax!CAD:tektronix!zehntel!sytek!menlo70!hao!cires!harkins
Newsgroups: net.micro
Title: fiber optics 232
Article-I.D.: cires.2010
Posted: Thu Mar 17 12:51:52 1983
Received: Thu Mar 24 07:13:47 1983

for really long runs of rs 232, there are some new rs 232 fiber optics
extended line units that i've seen in Computer Design recently; anybody
try one yet?
btw, MacNamara's "Technical Aspects of Data Communicatons," from DEC
press, has some neat charts that supposedly say what you can expect
from a couple of different kinds of cabling as to distance and speed;
in general though, the better the cable, the further you can violate
the rs 232c spec; i use Belden 8777 reliably to 300 ft. at 9600, which
incidentally seems to tally with MacNamara's upper limit.  ribbon cables
also have a problem of no shielding typically, which doesn't help; i found
one of our users, who had a "bad" modem, had managed to pass the ribbon
cable from modem to terminal, right between the AC outlets, picking up
lots of garbage; never had that arise with shielded wire, but those
ribbon jobs are sure easy to make...  ernie harkins