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RS232 Colours

Discussion in 'Electronic Basics' started by Parasites Lost, Feb 27, 2005.

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  1. Hi all,

    I have a RS232 connector which only has 4 wires (ripped from an old

    The wires have been colour and text labeled:

    RT - White
    V - Blue
    RX - Orange
    G - Green

    IIRC from a cable wiring guide,
    RT = pinout 3 (transmit)
    V = 7 (RTS)
    RX = 2 (Receive)
    and G = 5 (ground)

    Have I got the pinouts right?
    The colour of the wires are a bit confusing.

  2. Chris

    Chris Guest

    Good morning. It's nice to see the Milton fans are up and around
    during Lent.

    Use this link and an ohmmeter to help you determine the relationship
    between DB-9 or DB-25 pins and their RS-232 function:

    Here's what they have to say (formatted in fixed font):

    DB-9 Pin Corresponding DB-25 Pin Signal Function
    2 3 RD Received data
    3 2 TD Transmitted data
    8 5 CTS Clear to send
    7 4 RTS Request to send
    6 6 DSR Data set ready
    5 7 SG Signal ground
    4 20 DTR Data terminal ready
    1 8 DCD Data carrier detect

    I wouldn't rely on wire insulation colors.

    "[He] who overcomes lice
    By force hath overcome but half his foe;
    He must get the nits, too." ;-)

  3. Rich Webb

    Rich Webb Guest

    There are no color standards for RS-232 wiring, you have to go by the
    pin position. For DB-9 connectors its

    1 NC
    2 RXD
    3 TXD
    4 DTR
    5 GND
    6 DSR
    7 RTS
    8 CTS
    9 NC
  4. He's correct, the wiring color code is not defined for RS232
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