to: CC: * Stan Hoeppner <s...@hardwarefreak.com> [110328 06:24]: > Moczik Gabor put forth on 3/28/2011 12:01 AM: > > Stan Hoeppner wrote: > >> We bought DB25 plugs in bags of 100, and used spooled CAT5 as the noise > >> rejection is many times that of CAT3, allowing greater distances across > >> sprawling warehouses. > > > > RS-232 uses single-ended signaling and requires shielded cable, twisted > > pair doesn't help either.
Shielding provides immunity (not always perfect) against radio-frequency interference. But shielding (aside from an enclosure or conduit of iron or steel) provides no immunity against magnetic fields. If an RS-232 cable does not run near electric motors or switchgear, or make a long run parallel to power cables, and if radio-frequency interference is not a problem, then CAT5, CAT3, or even multiple strands of lamp cord may be satisfactory, without a shield. In fact, lamp cord -- typically 18 AWG stranded copper -- should allow longer runs, because of its much lower resistance (and thus, lower signal attenuation). And, at some point, capacitance of the circuit can become a problem, because it limits the usable data rate. RLH -- Who is this that darkeneth counsel by words without knowledge? - Job 38:2 -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20110328083033.GB3041@cromwell.tmiaf
