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Re: USB "null modem" cables and related Linux driver questions


On Fri, Jun 01, 2018 at 02:16:47PM -0500, Richard Owlett wrote:
> On 06/01/2018 09:01 AM, Michael Stone wrote:
> >I can't think of any applications where that's going to be better
> >over a pair of USB-Serial dongles than a pair of USB-Ethernet
> >dongles.
> Please read my stated goals.
> Not my PREsumed goals.
> *ROFL*

Laugh all you want at people trying to help you, but time and time
again you end up posting volumes of text here without finding a
solution because you suck at concisely describing what you want to
achieve. Everyone else fails to understand you, every time, so is
everyone just stupid, or is it that the common factor here is you?

Your first email said you wanted your machines to "communicate".
That's as specific as you got.

Dan then tried to narrow it down to one specific form of
communication by spending a lot of their time listing out everything
they could think of that you might have meant, and you replied,
"Your list pretty much covers it." Useless and frustrating.

Then Stefan tried:

> > What kind of "communicate" do you need there?

Your response?

> Essentially any :/

I don't know what kind of response you expect to that uselessly
vague comment. By doing that you force people to spend a lot of
their time trying to cover every base, and then you complain at them
when they try. It really seems like you just want to complain when
people try their best to help you, even against your best efforts.

I expect to just get a barrel of whinging back for this, but I hate
to write a totally useless email myself, so…

You mentioned you want to transfer files.

If both machines have Ethernet interfaces then (as you've already
been advised) the simplest, most reliable and most performant way
will be direct Ethernet connection, or connection via a switch. If
file transfer is your goal, no need to bother with USB.

If somehow these machines don't both have Ethernet and USB really is
the only way, then again as you've already been advised, USB
Ethernet is the way to go.

We are now leaving the realms of simplicity and performance for more
subjective lands of doing things "just because" or for the retro
computing experience. You can certainly use a pair of USB serial adaptors
and then run a null modem cable between them, then run PPP over
that. Absolutely no idea why you would want to do this rather than
run Ethernet over USB. Instead of PPP you could use more arcane
forms of serial data transfer like zmodem or kermit.

If it's just a console you want, i.e. the console output and login
prompt from one machine to appear in a serial terminal program on
the other, then you can do that over Ethernet too! See "netconsole".

For a serial console when you don't have Ethernet (or want it
separate from the Ethernet infrastructure) then again it's USB
serial dongles on both ends, a null modem cable in between, then use
a serial terminal emulator like minicom or screen on the end you
want to be the client. There are configuration details involved for
the server end to get it to send console output to this USB-serial,
and put a login prompt on it.

Ask which parts you need more info on. Please be specific. Please
don't make this harder than it needs to be!


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