Xref: utzoo comp.sys.ibm.pc:25876 comp.dcom.lans:2515 comp.dcom.modems:3552 Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!shelby!polya!kaufman From: kaufman@polya.Stanford.EDU (Marc T. Kaufman) Newsgroups: comp.sys.ibm.pc,comp.dcom.lans,comp.dcom.modems Subject: Re: RS-232 vs. V.35 Keywords: maximum distance Message-ID: <7548@polya.Stanford.EDU> Date: 9 Mar 89 17:19:40 GMT References: <1766@umbc3.UMBC.EDU> <4287@ingr.com> Sender: Marc T. Kaufman Reply-To: kaufman@polya.Stanford.EDU (Marc T. Kaufman) Followup-To: comp.sys.ibm.pc Distribution: na Organization: Stanford University Lines: 23 In article <4287@ingr.com> goodloe@ingr.com (Tony Goodloe) writes: >In article <1766@umbc3.UMBC.EDU>, smith@umbc3.UMBC.EDU (Fred Smith) writes: .> ... I would like to know is if there exists an effective "maximum" .> or standard distance for running CCITT V.35? >If somebody can point me to the page number in (one of the several >standards associated with) the V.35 spec that talks about distance, I >sure would appreciate. All we have been able to find is (paraphrased) >"Don't run it a distance that it won't work at. This distance will be >shorter as the data rate increases." Big help. I love standards :) Nevertheless, that is the best statement of maximum distance I can think of. For instance, with RS-232, the "50 foot" limit is an absolute worst case based on 20KB data rate, recommended rise-time limiting, use of the recommended current limiting drivers, high capacitance cables, and +/- 3 volt (minimum) swings. Now you just can't buy components that are that lousy in all respects! The real answer is that you can run as far as you can receive good waveforms. Balanced circuits typically have a little more margin than unbalanced. I can't imagine why you care, if you can get the circuit to work, unless you are expecting someone to rewire with zip-cord when you aren't looking. Marc Kaufman (kaufman@polya.stanford.edu)