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

Russell Senior russell at personaltelco.net
Fri Jun 1 02:44:37 PDT 2018


2 of these:
https://www.amazon.com/AmazonBasics-1000-Gigabit-Ethernet-Adapter/dp/B00M77HMU0/
1 of these:
https://www.amazon.com/AmazonBasics-RJ45-Cat-6-Ethernet-Patch-Cable-3-Feet-0-9-Meters/dp/B00N2VISLW/

or, if you really want pain and slow file transfers:

2 of these:
https://www.amazon.com/Sabrent-Converter-Prolific-Chipset-CB-DB9P/dp/B00IDSM6BW/
1 of these:
https://www.amazon.com/female-slimline-transfer-serial-adapter/dp/B075XGRLXW/

or, cheaper still:

https://www.amazon.com/Sumind-Raspberry-Programming-Windows-Supported/dp/B01N4X3BJB/
and some jumper wires to do the crossover.

Any of those three options will give you a usb-to-usb link.  Doing file
transfers over serial, I'm afraid to guess how you plan to do that.
Obviously, there are tools to do it, because it was what you had to do
before they invented ethernet.  You could probably run ppp on the serial
port and even get a network link over it.  Or just use xmodem, kermit or
something similar.  Oh, and buy some bamboo splinters to stuff under your
fingernails at the same time, you masochist!

On Fri, Jun 1, 2018 at 2:17 AM, 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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