RJ45 Cat5 cable query

Discussion in 'General Discussion' started by martymonster, Mar 9, 2006.

  1. martymonster

    martymonster

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    Just want to clarify something.

    When connecting units with RJ45 cable. I gather by looking at the special wiring setup in the installation PDFs that you cannot just use a normal PC Blue Cat5 cable or a Cat5 patch cable without rewireing the ends on each connector to what is specified in the installation guides.

    Would this be correct?

    Eg: Adding a 5500CN to a system without DIN rail units and then connecting a 5800 wireless gateway to the 5500CN
    Ignoring the fact that that they may be supplied with CBus Cat5 cable.

    Thanks
    Marty
     
    martymonster, Mar 9, 2006
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  2. martymonster

    NickD Moderator

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    Please don't!

    The reason for the non-standard arrangement of the cores on C-Bus RJ45s is to get the best noise immunity where the 2 pairs used for C-Bus are run in parallel.

    Technically, if you're connecting between 2 *C-Bus* RJ45 sockets, any straight through cable will work, but it's a VERY BAD IDEA...

    If you inadvertently mix up the cables and end up plugging C-Bus into an ethernet port you're likely to damage something.

    Nick
     
    Last edited by a moderator: Mar 9, 2006
    NickD, Mar 9, 2006
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  3. martymonster

    martymonster

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    Thanks for the confirmation.

    Marty
     
    martymonster, Mar 9, 2006
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  4. martymonster

    ashleigh Moderator

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    The pink cable also has a higher insulation rating than standard blue Cat 5, which is needed for compliance with some of the wiring rules.

    It is far preferable to always use C-Bus cable for C-Bus installs. It might cost a bit more but there is a good reason for that. It is certainly not profiteering by CIS.
     
    ashleigh, Mar 10, 2006
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  5. martymonster

    martymonster

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    Thanks ashleigh

    Marty
     
    martymonster, Mar 10, 2006
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  6. martymonster

    martymonster

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    Just another quick question :) as my initial question may not have been clear.

    Looking at the 5500CN Installation book for example. It shows that the Blue + Orange cables go to the C-Bus Pos connection.
    Then below it, it shows that these cable use Pins 4 and 6 in the RJ45 connector.
    So, my question is->

    If connecting say a 5500CN to an old CBus power supply (5100PS i think, No RJ45 connectors), one end of the cable is a RJ45 plug wired as per the example in the 5500CN booklet
    Pin Cable
    1 Green/White
    2 Green
    3 orange/White
    4 Blue
    5 Blue/White
    6 Orange
    7 Brown/White
    8 Brown

    and the other end has the following (NON RJ45) such
    Blue + Orange to C-Bus POS on Power Supply
    Orange/White + Blue/White to C-Bus NEG on power supply.

    So, the RJ45 end plugs into the 5500CN and the other end has 4 wires connected to the 2 terminals of the power supply (POS and NEG).

    IS this correct?

    Marty
     
    martymonster, Mar 10, 2006
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  7. martymonster

    JohnC

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    Yes, that is correct. What we usually would do is take a standard (short pink) Cbus jumper cable which is supplied with each DinRail device. Then chop off one end. But that results in a very short connection lead.

    It's no hassle if you have a RJ45 crimper, and we make our own patch cords using Pink (or shock horror) blue Cat5 all the time for Cbus. In fact, a couple of our office computers have Pink LAN leads for some reason :eek: Anyway, if you don't have a crimper to then you have to borrow one or chop up a Cat5 LAN cable (blue, just paint it pink with Tipex).

    There's no problem with using standard LAN Cat5's with RJ45 on each end (ie: standard LAN, non-cross-over) - they work fine and there's no problems with pin / pair / twist assignments. But the big problem with chopping one end of a "non-Cbus" Cat 5 cable is that they may not have the same colour coding as recommended by CIS. Eg: Pins 4/5 might not be connected to blue pair !

    So, what you have to do is ensure that the RJ45 pin assignments (as you detailed in the previous post) end up on the correct Pos and Neg terminals of the 5100PS or other non-RJ45 Cbus unit (also all the Cbus switches).

    In Summary : If using Cbus cables or terminating the wiring yourself - definitely wire using the colour coding recommended by CIS. If using a pre-terminated NON-Cbus cable, then ignore the colours and work strictly to the pin assignments.

    LOL, I hope that made sense - John
     
    Last edited by a moderator: Mar 10, 2006
    JohnC, Mar 10, 2006
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  8. martymonster

    martymonster

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    Thanks JohnC, that is exactly what I wanted to know.

    I do have a crimper (bought it today:D ), a wire stripper for UTP cable and some RJ45 plugs.

    Once again,
    TANX

    Marty
     
    martymonster, Mar 10, 2006
    #8
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