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RS 232 9-pin D connection distance limitations

Discussion in 'Networking' started by sqrob, Apr 13, 2004.

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  1. sqrob

    sqrob Thread Starter

    Joined:
    Jan 25, 2003
    Messages:
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    would like to run a wire from a legacy LED display to a desktop pc. both have rs232 9-pin D ports. the sign claims that it can be programmed from a simple communication software.

    i have read that rs232 9-pin runs can go a max of 25' (some sites say 50 feet) before requiring a signal booster.

    can i use 9-pin D > RJ 45 adapters at both ends and run CAT-5 network cable (+/-300' max run) between them avoid using signal boosters?

    the task will involve running approx 120' of wiring through some difficult crawlspaces and attics. would like to avoid having to try to run the CAT-5 just to find out that it too will need a signal booster every 25'. there is simply nowhere to easily get power to the signal boosters, once they are in the walls and attics.

    any thoughts?

    TIA

    sqrob
     
  2. JohnWill

    JohnWill Retired Moderator

    Joined:
    Oct 19, 2002
    Messages:
    106,418
    FWIW, although the RS-232 specification does indeed say one thing, the distance you can run an RS-232 line depends on a host of factors, one of the most important is bit rate. If you run at 300 baud, 100's of feet are no sweat. I've run 9600 baud 200 feet with low loss cable, and never had a problem.

    CAT5 cable isn't necessarily the best option, what you really want is some of the low capacitance shielded cable that Black Box used to sell for long runs. It's been years since I've even thought about running RS-232 long distances, but we used to do it a lot for securities trading firms on Wall St.

    You can also check into short haul modems, or RS-232/RS-422 converters, they'll run several thousand feet without any problem. Places like B&B Electronics have them...
     
  3. sqrob

    sqrob Thread Starter

    Joined:
    Jan 25, 2003
    Messages:
    2
    johnwill,

    here are the specs i found for the sign.

    BAUD : 300
    STOP : 2
    DATA : 8
    PARITY : NONE
    DUPLEX : FULL

    i'll look for the cable you have suggested and give it a go.

    many thanks for the speedy reply.

    sqrob
     
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