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Newbie RS-232 question

Discussion in 'Electronic Basics' started by Bob Pownall, Nov 25, 2006.

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  1. Bob Pownall

    Bob Pownall Guest

    I've got a couple of female-female RS-232 cables.

    I initially thought they were null-modem cables, but when I checked the
    pin connection, this is what I found:
    1 -> 7,8
    2 -> 3
    3 -> 2
    4 -> 6
    5 -> 5
    6 -> 4
    7 -> 1
    8 -> 1
    9 -> not connected

    As I understand it, a null modem should be like this:
    1 -> 4
    2 -> 3
    3 -> 2
    4 -> 1,6
    5 -> 5
    6 -> 4
    7 -> 8
    8 -> 7
    9 -> not connected

    There's no sign of a part number on either cable.

    Any ideas of what I have?

    Bob Pownall
     
  2. See http://www.lammertbies.nl/comm/cable/RS-232.html
     
  3. Bob Pownall

    Bob Pownall Guest

    Richard Seriani, Sr. wrote:
    <Summary: A pointer to the answer to my question.>

    Thanks! Looks like they _were_ null modem cables, just not the type I
    was familiar with. Specifically, they're null modem cables with
    partial handshaking, and I was only familiar with null modem cables with
    loop-back handshaking.

    I'll have to bookmark that site - looks useful.

    Bob Pownall
     
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