Mine was on "dry pair" leased line from the phone company over the same bundle that served telephone to the buildings. Phone company was well aware as it was part of a specifically negotiated contract. Several hundred dollars per month at the time if I recall. I think it was 19200 baud, but... fuzzy memory. I do recall that it was a "it just works" situation I don't recall having any downtime or communication difficulties with that specific link. On Wed, Sep 19, 2018 at 1:28 PM RussellMc wrote: > On Tue, 18 Sep 2018 at 05:27, Denny Esterline > wrote: > > > Hmmm... It's been near twenty years ago, but I've run RS-232 on copper > > over two miles. Granted at a lower baud rate and with actual line drive= rs > > that were operating near +-25v. > > > > Info only: > > Long long long long ago (probably almost 40 years) I trialled RS232 at 20= 0 > (!) baud on copper. > I now do not recall levels used but it was either 0/+5V or standard RS232 > +/- 12V. > > Range seemed to be "as many miles as you wanted". > This was using telephone cable pairs which were brought into a building > from a large number of telephone exchanges scattered around the city. > I could daisy chain several exchange links if desired. > (Someone else had set the arrangement up for other purposes and I made us= e > of it). It seemed that at 200 baud something akin to "wet string" would > suffice. > > I don't know what effect this may have had on telephone "traffic" in the > cables. I assume this was thought of at the time but maybe not. It was on= ly > done as a short trial. > > > Russell > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .