On Jan 9, 2012, at 11:25 PM, David J Taylor wrote: >> 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. > > 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"!
It sounds like you are actually looking for balanced/differential wiring, which would be RS-422 (as the other David mentioned). This would have much better timing characteristics and common-mode noise rejection, and thus permit operation at much higher speeds over longer distances. You'd need a RS-422 to RS-232 converter with most commodity PC serial ports, as they tend to use a descendant of the NatSemi 8250/16550 UART, instead of something like the Zilog UARTs used by some multiport serial/PBX cards. Regards, -- -Chuck _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
