On Fri, 26 Jun 2020 19:13:04 +0200, "R.Wieser" 
declaimed the following:

>I'm aware of that  But as USB speeds are much higher I could imagine that
>some of that translates to higher serial speeds too.  Like the below link
>already shows a 3.5 times higher speed than a regular UART.
>
>http://www.a2s.pl/en/atc-810-p-3703.html

 You probably won't achieve that without using very high end serial
cables between the two ends, and that cable may need to be a null-modem
wiring so that Tx on one end connects to Rx on the other end. Normal serial
cables are DTEDCE where the "sense" of the connections is reversed on the
DCE side.

https://zone.ni.com/reference/en-XX/help/370984T-01/lvaddon11/987x_rs232dtevsdc
e/
(has an error in the dtedce--dcedte diagram -- someone failed to flip
the arrows on one side; it should be a mirror image)

 Finding any serial cables is getting difficult, much less ones that
could take the highest speed (I've got a laptop driving a USBserial DB-9,
which then feeds a DB-9DB-25 adapter, onto a DB-25DB-9 cable, all to
connect to a Kenwood TS-2000, and I'm having troubles getting reliable
signals through that [and the only thing it needs to send is DTR and/or
RTS, to toggle the PTT on the radio]).

 I need to order a couple of DB-9FDB-9F serial cables, and null-modem
cables.

>
>> Use a CAT-5/CAT-6 cable from the R-Pi to one of your
>> separated networks, and configure the R-Pi WiFi to connect
>> to the other network with the WiFi router.
>
>:-)  Nope.  Both will be wired (like all my connections), or nothing goes.

 I only suggested using the WiFi during feasibility testing, as the R-Pi
3B+ /has/ two network interfaces... cable and Wifi. After you've worked out
what software protocols will provide the desired access, you could consider
spending the money for USB dongles.

 And on that -- if you're going to spend the money on dongles, might as
well go USBEthernet. I suspect you have a lot more CAT-5 (or even CAT-6)
jumpers lying around, and many modern Ethernet devices have auto-detect of
port polarity (no need to worry if a null-modem or cross-over cable is
needed).

{I need the USBserial as I have some old equipment that used serial: the
aforesaid TS-2000, old BASIC Stamp boards, I think I have a Propeller board
with RS-232, besides having had a previous life where serial was needed. I
also have something like three USB2 SIIG USBEthernet dongles -- also from
that previous life, and a pair of USB3 SIIG dongles}
>
>Regards,
>Rudy Wieser
>


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