RS-232 has more limitations than just cable capacitance. RS-232 is a single-ended communication protocol (on the physical level), so it's noise immunity is not very good. This is especially a problem if you're running the cable in an electrically noisy environment (like a cable tray or wiring closet(s), etc.).
If you need to run a long distance, why not just convert your RS-232 signal to RS-422 where you can safely run a 9600bps signal out to over a kilometer? All you need is a 2 pair cable, ideally with a shield, provided you don't need hardware flow control. The converters are usually cheap, maybe $50 or so per end unless you need electrical isolation. -Bill > -----Original Message----- > From: cisco-nsp-boun...@puck.nether.net [mailto:cisco-nsp- > boun...@puck.nether.net] On Behalf Of Richard Halfpenny > Sent: Wednesday, April 08, 2009 7:32 AM > To: cisco-nsp@puck.nether.net > Subject: Re: [c-nsp] Max length of 9600 serial over CAT5e > > Sam Stickland wrote: > > Hi, > > > > What's the maximum length of you can run async-serial (9600 baud) > > over CAT5e (from a terminal server to console port). > > > > My google-fu has failed me. > > If I remember correctly, the spec for RS-232 says the maximum > capacitance of a cable can be 2500pF at 20kbps. A Cat5e of approx 46pF > / metre would give you a maximum length of 54 metres. At 9600bps you > could probably drive slightly longer. > > Rich > > -- > Network Operations > Exa Networks Ltd :: AS30740 > richard.halfpe...@exa-networks.co.uk > > _______________________________________________ > cisco-nsp mailing list cisco-nsp@puck.nether.net > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/