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Who-da Thunk?

Discussion in 'General Electronics Discussion' started by CDRIVE, Nov 21, 2016.

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  1. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    I want to preface this with a bold statement.... I have just about every configuration of RS232 cables and adapters known to man and I have them in duplicate x 10.

    This morning the wife says.. "Gee, this is odd. This month you didn't buy a single China - Ebay item". That got me to thinking. Since PC RS232 ports have become as rare as Hen's teeth we all have become very comfortable with USB/RS232 converter dongles. They're fine for what they're intended for but if you're hooking up a Null Modem link it requires two USB/RS232 dongles with a F/F Null Modem (crossover) adapter connecting the two dongles. I thought why not buy a nice compact USB_Serial_Serial_USB Null Modem cable? I figured China must have packaged this by now.

    Unless my search terms suck it doesn't exist. Yes, I realize that if each USB end is going to be plugged into the same PC each USB jack would have to assign a different ComPort# for each USB port.

    I think my description is clear enough but if a drawing of what I'm looking for is needed I'll draw it.

    Chris
     
  2. chopnhack

    chopnhack

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    LOL

    Esplain Lucy, what are you trying to accomplish? Drawing is good too!
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Tell us what you want to do, not how you think it should be done ;D
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    CDRIVE and hevans1944 like this.
  5. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Thanks, Harald!
     
  6. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Actually I was running a forum deciphering test. :D You all failed miserably. No CIA, MI-6 annalist jobs are waiting for you. :p

    OK, I'll post a schematic or sketch later.

    Chris
     
  7. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Harald goes home with one gold star for understanding my question by a factor of 50%.

    OK, here's my explanation. In the old days when all PC's had RS232 ports you could link two PC's with a Null Modem cable. If a single PC had two serial ports you could also communicate between the two ports using the same Null Modem. This was handy if you were testing VB MSComm code between two VB projects on the same PC. The same Null Modem would be used when communicating between a PIC simulator app that I have that includes a Virtual Serial Terminal.

    Fast forward to today where finding an RS232 port on a PC is rare but they're all bristling with USB ports. To do what I described above requires a [USB to Serial} {Null Modem} {Serial to USB] as shown in the attachment and how I've been doing it for years. It's a royal Pita and I would love to have it packaged as a single USB to RS232 to USB cable.

    Chris
    upload_2016-11-23_8-30-58.png
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    But, for goods sake Chris, why would you need the detour with the RS232 in between? Is it because you wnat to use a virtual COM port for communication? The I think this is what you're looking for: two USB plugs connected by a cable. Each plug has its internal FTDI chip which emulates a virtual COM port (VPC).
     
  9. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Yes to all of your questions Harald. That's exactly what I'm looking for. Thanks!! That cable is unique because it can be used in Virtual CommPort (VCP) mode or direct USB-2 to USB-2. Depending on the drivers used for the null modem link. They supply both and can be selected and changed to use in either mode. Cool!
    http://www.ftdichip.com/Support/Doc...I_Drivers_Installation_Guide_for_Windows7.pdf

    DUNKA!
    Chris
     
  10. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    You know the old saying "You gain something. You loose something"? Well it just hit me that using that USB Null Modem cable I loose the use of my inline RS232 LED testers that I've been using for well over a decade, maybe two.

    http://www.ebay.com/itm/RS-232-DB25...321466?hash=item2cb0f3b07a:g:7LcAAOSwQ15XOZ8l

    I find it humorous that after all these years they still haven't corrected the typo "DRT" that should read "DTR".

    http://www.ebay.com/itm/Startech-MT...828794?hash=item33bd36f9ba:g:Qq4AAOSw2GlXEBzq


    Oh well, you can't win em all.

    Chris
     
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