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serial rs232 cable help?

Discussion in 'General Electronics Chat' started by BryWY, Apr 6, 2016.

  1. BryWY

    BryWY Member

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    I am wondering if you could take a few minutes to assist me as I am in a bit of a bind ...I live in a remote area where I do not have access to a computer outlet where I can go out an buy a replacment cable for my Desay master vinyl plotter which I have pending jobs get done asap.

    I accidently broke the male end going to my plotter off my cable. I found a generic male end all wires one color I would like to use. So I spliced the cable and found there are 7 wires in the cable red white brown green blue yellow and copper on outside.

    I am wondering where I can g to find the correct wiring configuration ...any assistance you could provide would be much appreciated.

    Thanks
     
  2. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Search the internet for "serial cable pin out"
    There are two options. In this picture 2-3 and 3-2. But some are 2-2 and 3-3.
    [​IMG]
     
  3. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    A few things would help:
    Assume serial
    Assume D style connectors
    In this case, pins or sockets determine male or female

    Post a pic of the plotter connector

    You can't screw up RS232 in terms of connections. You won't hurt anything if they are connected wrong. Manufactures have made lots of mistakes over the years.

    1. Pins or sockets in the connector on the plotter
    2. # of pins (could be 9 or 25)

    1. Assume 9 pin on the PC, possibly through a USB to serial converter?
    2. Probably few things woul a 9 pin male
    3. They are eroneously called a DB-9, but they are really DE-9 connectors.

    If you know if the plotter is a DTE or DCE device that would be cool.

    So, you likely need
    DTR
    DSR

    TXD
    RXD
    SG

    DSR
    DTR

    PG (protective ground or the shield) - One side only is good

    If you can measure the voltage from SG to DSR nd SG to DTR with the plotter on, that should tell us if it's a DTE or DCE.

    You likely need a standard serial printer cable to either a 9 pin or 25 pin connector.

    The gender used to work

    Believe it or not, the wires may actually have numbers written on them. Look carefullly.
     
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  4. dave

    Dave New Member

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  5. BryWY

    BryWY Member

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    It is 9 pin ...male from plotter to pc 9 pin female (I would like to convert it to usb eventually) to use it on my laptop.
    Tried standard universal did not work says on plotter must be sr 232...will double check

    will post pic in a few minutes....
     
  6. JimB

    JimB Super Moderator Most Helpful Member

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    Rs232 is the most abused non-standard "standard that ever was.

    I am not quite sure what you are saying here, are you describing the cable?
    However, I guess that on the computer is a 9 pin male connector, if the connector on the plotter is a 9 pin female, try a straight through connection.

    ie.

    Pin 1 to pin 1
    Pin 2 to pin 2
    etc, all the way to
    .
    .
    .
    Pin 9 to pin 9

    JimB
     
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  7. BryWY

    BryWY Member

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    That makes sense will give that a go.....
     
  8. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    http://www.jspayne.com/io/schematics.html

    You don't need pin #1 or Pin #9. That will give you 7.
    Ideally, the shield can go to one of the chassis at ONE end only.

    Straight thru makes the most sense. 2-2 ; 3-3...8-8
     
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  9. BryWY

    BryWY Member

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    just tested the regular generic serial cable that doesn't work with and it is pin for pin straight through so must be a null modem cable
    [​IMG]
     
  10. MaxHeadRoom78

    MaxHeadRoom78 Active Member

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    Null modem is not straight through, the connections are crossed for handshake etc. As in post #2.
    Max.
     
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  11. BryWY

    BryWY Member

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    just checked pin 5 and 7 with volt setting on 10 dc made needle redline....not exactly sure how to use vom
     
  12. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Be careful: The Pin numbering is weird and not expected.

    Your empty pins should be one on one row and one on the other at opposite ends. (diagonal).
     
  13. BryWY

    BryWY Member

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    my little ribbon cable that i plug in plotter male has number one pin with white stripe...now what configuration would you suggest i try?
     
  14. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    The REAL Rs232 had voltages of -25 and +25; Typically you see +12 and -12. Between +3 and -3 is the dead zone. Things get weird when the levels are +-5V and thing get weirder yet when you have inverted TTL 3.3 and 5V. You should never see that.

    I'm initially interested in pin 5 to 4 and pin 5 to 6 on the plotter. Pin 5 is likely connected to chassis. No cable attached, but plotter on.
     
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  15. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    We definitely need a couple of pictures. There is an Upload a File.

    So, your plugging in a 9 pin ribbon to a 9 pin ribbon with D connectors on them?

    Basically, they are meant to be squished together because they are IDC or Interdigitated contacts. They don't make very good null modem cables.
     
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  16. BryWY

    BryWY Member

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    pin 5 and 7 together give me a reading of around 18 volts
     
  17. BryWY

    BryWY Member

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    just need soething temporary for now to finish a couple of jobs and order a new cable
     
  18. BryWY

    BryWY Member

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    the cable that worked and the ribbon cable temporary fix
     

    Attached Files:

  19. BryWY

    BryWY Member

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    the 5 and 6 get no reading
     
  20. BryWY

    BryWY Member

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    the5 an 3 give a negative reading
     
  21. BryWY

    BryWY Member

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    all other pins with 5 show no reading
     

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