On 2012-01-10, David J Taylor <[email protected]> wrote: >> On Jan 8, 2012, at 11:45 PM, David J Taylor wrote: >>> Chris, it also occurs to me to enquire exactly how the RS-232 data is >>> being carried over the cat-5 cable. What is the wiring? >> >> Searching for "RS232 over RJ45" suggests the standard pinout is known as >> EIA/TIA 561. >> Basically, it closely resembles the EIA/TIA 574 (DB9) wiring, but DSR >> and RI have been combined. >> >> Regards, >> -- >> -Chuck > > I was expecting that, for timing purposes, the four pairs would be used > as: > > - TXD/ground > - RXD/ground > - DCD/ground > - unused > > i.e. that every relevant RS-232 line was carried with a ground on the > twisted pair. This would be better than some random "pushing of pins"!
The problem of course is that all of those grounds are common grounds at the DB9 interface ( and probably at the gps as well) which means that the ground current would be carried on all three ground wires, giving a common mode signal on each pair. > > Cheers, > David > _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
