[PLUG] Experiences with USB "null modem" cables.

Thomas Groman tgrom.automail at nuegia.net
Sat Jun 2 03:56:56 UTC 2018


On Fri, 1 Jun 2018 04:17:06 -0500
Richard Owlett <rowlett at cloud85.net> wrote:

> On 05/31/2018 09:12 AM, Johnathan Mantey wrote:
> > Richard,
> > Is there a reason you don't use point to point RJ45 ethernet?  
> 
> YEPP ;/
> 
> > If a PC has USB it almost always has RJ45 ethernet.  
> 
> As you say "*almost*"
> 
> >  If neither side has MDIX then RJ45
> > crossover cables are available to complete the connection.  Why do
> > you have an affinity for USB cable solutions?  
> 
> I summary my absolute required elements include all below:
>    existence
>    known to work
>    conveniently physicallt available
> 
> I'll admit there also are some preferences:
>    scratch an itch that has existed since days of USB 1.0
>    explore an un-explored realm
> 
> And winner is  USB "null modem" cable ;}
> 
> 
> 
> > 
> > On Thu, May 31, 2018 at 2:39 AM, Russell Senior
> > <russell at personaltelco.net> wrote:
> >   
> >> Good luck!
> >>
> >> On Thu, May 31, 2018 at 2:17 AM, Richard Owlett
> >> <rowlett at cloud85.net> wrote:
> >>  
> >>> On 05/30/2018 03:43 PM, Russell Senior wrote:
> >>>  
> >>>> The one I have implements a USB-net interface,
> >>>>  
> >>>
> >>> I did a DuckDuckGo search for "USB-net interface" {with/without
> >>> quotes}. Found several interesting links, but not sure if any are
> >>> what you are speaking of. A link to specific device(s) you refer
> >>> to?
> >>>
> >>> so it's effectively an ethernet cable.  
> >>>>  
> >>>
> >>> I purposely used the term "null modem". I date from an
> >>> era/industry  
> >> where  
> >>> where 20 mA current loop was preferred over RS-232C for its
> >>> noise  
> >> immunity.  
> >>> Since USB 1.0 I've considered "universal" of USB an unfortunate
> >>> choice of adjectives. The intrinsic implementation of hardware to
> >>> forever be  
> >> either a  
> >>> *MASTER* or slave is annoying.
> >>>
> >>>   Most modern distributions just work.  The one you link is  
> >>>> a USB-to-serial-to USB.  That is not ideal for transferring
> >>>> files. 
> >>>
> >>> Depends on your metric.
> >>>
> >>> If you  
> >>>> are unclear on what the "link" cable supports, you can always
> >>>> just buy  
> >> two  
> >>>> usb-ethernet adapters and an ethernet cable to go in the middle.
> >>>>  
> >>> That explicitly is to be avoided as an unnecessary complication.
> >>>
> >>> Maybe more adpatable than a "link cable".  
> >>>>  
> >>>
> >>> I want a USB cable that is as functional (my metric) as a RS-232
> >>> cable of decades past. The only observable difference would be
> >>> max available  
> >> speed.  
> >>>
> >>>
> >>>
> >>>
> >>>  
> >>>> On Wed, May 30, 2018 at 12:49 PM, Richard Owlett
> >>>> <rowlett at cloud85.net> wrote:
> >>>>
> >>>> ARGHHH. New it was going to be that kind of day ;/  
> >>>>> Any problems &/or comments?
> >>>>>
> >>>>>
> >>>>>
> >>>>> On 05/30/2018 01:53 PM, Russell Senior wrote:
> >>>>>
> >>>>> Yes  
> >>>>>>
> >>>>>> On Wed, May 30, 2018, 10:54 Richard Owlett
> >>>>>> <rowlett at cloud85.net>  
> >> wrote:  
> >>>>>>
> >>>>>> I've come across a "USB Null Modem Cable" by Future Technology
> >>>>>> Devices 
> >>>>>>> International
> >>>>>>> [http://www.ftdichip.com/Products/Cables/USBtoUSB.htm  
> >> ].  
> >>>>>>>
> >>>>>>> It would seem an appropriate solution for some file sharing
> >>>>>>> between  
> >> two  
> >>>>>>> Linux machines which have only USB 2.0 in common.
> >>>>>>>
> >>>>>>> Has anyone used this or a similar product.
> >>>>>>> TIA
> >>>>>>>
> >>>>>>>  
> 
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> PLUG at pdxlinux.org
> http://lists.pdxlinux.org/mailman/listinfo/plug

If your using one of those fad or cheapo laptops with no IO but WiFi,
you could use a ptp wireless link too

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